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Prof. Dr. Stefan Mátéfi-Tempfli

Faculty of European Campus Rottal-Inn

Professor

EC 2.09

Sortierung:

Lecture

Stefan Mátéfi-Tempfli
R. Raşcu

Driver pentru imprimante PB sub sistemul de operare RSX11M.

In: Sesiunea de comunicări ştiinţifice

Oradea, Rumänien

1986 (1986)

Journal article

Stefan Mátéfi-Tempfli

Supply Source for Superconductor Electromagnets Controlled by Computer.

In: Sesiunea de comunicări ştiinţifice, published in Analele Universităţii din Oradea/Romania

(1997)

Journal article

Stefan Mátéfi-Tempfli

Recognition algorithm for phone numbers dialed in DTMF and PULSE mode.

In: Sesiunea de comunicări ştiinţifice, published in Analele Universităţii din Oradea/Romania

(1998)

Journal article

Stefan Mátéfi-Tempfli

The implementation of the PID regulator using numeric filter algorithm with infinite impulse response.

In: Sesiunea de comunicări ştiinţifice, published in Analele Universităţii din Oradea/Romania

(1998)

Journal article

Stefan Mátéfi-Tempfli
K. Bondor

Utilizarea compusului Mn3O4 ca element sensibil al unui traductor de temperatură.

In: Sesiunea de comunicări ştiinţifice, published in Analele Universităţii din Oradea/Romania

(1998)

Journal article

Stefan Mátéfi-Tempfli

Automatic four points Temperature Regulator System using the MSP430.

In: Sesiunea de comunicări ştiinţifice, published in Analele Universităţii din Oradea/Romania

(1999)

Lecture

Stefan Mátéfi-Tempfli
L. Piraux

Fabrication et étude des propriétés de nanofils supraconducteurs.

In: Journées de la matière condensée (JMC7)

Poitiers, Frankreich

28.08.-01.09.2000 (2000)

Patent

Stefan Mátéfi-Tempfli
L. Piraux

Multiple bath electrodeposition.

vol. C25D 5/10

Belgium

08.05.2001 (2002)

Journal article

F. Elhoussine
Stefan Mátéfi-Tempfli
A. Encinas
L. Piraux

Conductance quantization in magnetic nanowires electrodeposited in nanopores.

In: Applied Physics Letters vol. 81 pg. 1681-1683

(2002)

DOI: 10.1063/1.1503400

show abstract

Magnetic nanocontacts have been prepared by a templating method that involves the electrodeposition of Ni within the pores of track-etched polymer membranes. The nanocontacts are made at the extremity of a single Ni nanowire either inside or outside the pores. The method is simple, flexible, and controllable as the width of the constriction can be varied reversibly by controlling the potential between the electrodeposited nanowire and a ferromagnetic electrode. At room temperature, the electrical conductance shows quantization steps in units of e2/h, as expected for ferromagnetic metals without spin degeneracy. Our fabrication method enables future investigation of ballistic spin transport phenomena in electrodeposited magnetic nanocontacts.

Lecture

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

Fabrication and properties of superconducting nanowires.

In: Symposium on “Recent Developments in Nanoscience”

Academy of Science Belgien

11.-12.01.2002 (2002)

Lecture

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

Fabrication and properties of arrays of type II lead nanowires.

In: ESF Workshop, programme VORTEX

Prag, Tschechische Republik

03.-07.04.2002 (2002)

Lecture

S. Michotte
Stefan Mátéfi-Tempfli
G. Stenuit
L. Piraux

Fabrication and properties of arrays of type II lead nanowires.

In: Feynman Workshop

Louvain-la-Neuve, Belgien

22.05.2002 (2002)

Lecture

S. Michotte
Stefan Mátéfi-Tempfli
G. Stenuit
L. Piraux

Fabrication et propriétés d'un nanofil de plomb ou d'étain.

In: 8èmes Journées de la Matière Condensée (JMC8)

Marseille, Frankreich

27.-30.08.2002 (2002)

Lecture

F. El Houssine
Stefan Mátéfi-Tempfli
A. Encinas
L. Piraux

Nanocontacts magnétiques électrodéposés et conductance quantifiée.

In: 8èmes Journées de la Matière Condensée (JMC8)

Marseille, Frankreich

27.-30.08.2002 (2002)

Lecture

F. El Houssine
Stefan Mátéfi-Tempfli
A. Encinas
L. Piraux

Nanocontacts magnétiques et conductance quantifiée dans les nanofils électrodéposés.

In: 8ième Colloque Louis Néel

Gérardmer, Frankreich

24.-26.09.2002 (2002)

Lecture

F. El Houssine
Stefan Mátéfi-Tempfli
A. Encinas
L. Piraux

Electrodeposited magnetic nanocontacts and quantum conductance.

In: 47th Annual Conference on Magnetism and Magnetic Mateirals (MMM'02)

Tampa, FL, USA

12.-15.11.2002 (2002)

Journal article

F. Elhoussine
A. Encinas
Stefan Mátéfi-Tempfli
L. Piraux

Quantum conductance in electrodeposited nanocontacts and magnetoresistance measurements.

In: Journal of Applied Physics vol. 93 pg. 8567-8569

(2003)

DOI: 10.1063/1.1557341

show abstract

We present conductance and magnetoresistance measurements in magnetic Ni–Ni and Co–Ni nanocontacts prepared by electrodeposition within the pores of a track-etched polymer membrane. At room temperature, Ni–Ni constrictions show broad quantization plateaus of conductance during their dissolution into units of e2/h, as expected for ferromagnetic ballistic nanocontacts. Additionally, positive and negative magnetoresistance has been measured in Co–Ni nanocontacts.

Journal article

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

Current-voltage characteristics of Pb and Sn granular superconducting nanowires.

In: Applied Physics Letters vol. 82 pg. 4119-4121

(2003)

DOI: 10.1063/1.1582356

show abstract

Arrays of granular superconducting Pb and Sn nanowires (40–55 nm in diameter and 22 or 50 μm long) have been prepared by electrodeposition in nanoporous membranes. A simple technique has been developed to perform electrical transport measurement on a single nanowire. By sweeping the dc current inside the nanowire, we observed the formation of phase-slip-centers far below the critical temperature. In contrast, in voltage-driven experiments, an interesting S-shaped behavior has been observed in the nucleation region of these phase-slip-centers.

Journal article

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

Investigation of superconducting properties of nanowires prepared by template synthesis.

In: Superconductor Science and Technology vol. 16 pg. 557-561

(2003)

DOI: 10.1088/0953-2048/16/5/302

show abstract

We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have a uniform diameter of ~40 nm and a very large aspect ratio (~500). The diameter of the nanowires is small enough to ensure a one-dimensional superconducting regime in a wide temperature range below Tc. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied dc current (or voltage). The current-induced breakdowns in the voltage–current characteristics may be explained by the formation of phase slip centres. Moreover, dc voltage driven measurements reveal the existence of a new S-shape behaviour near the formation of these phase slip centres.

Journal article

D. Vodolazov
F. Peeters
L. Piraux
Stefan Mátéfi-Tempfli
S. Michotte

Current-voltage characteristics of quasi-one-dimensional superconductors: an S-shaped curve in the constant voltage regime.

In: Physical Review Letters - moving physics forward vol. 91 pg. 157001

(2003)

DOI: 10.1103/PhysRevLett.91.157001

show abstract

Applying a constant voltage to superconducting nanowires we find that its I-V characteristic exhibits an unusual S behavior. This behavior is the direct consequence of the dynamics of the superconducting condensate and of the existence of two different critical currents: jc2 at which the pure superconducting state becomes unstable and jc1

Journal article

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

1D-transport properties of single superconducting lead nanowires.

In: Physica C: Superconductivity and its Applications vol. 391 pg. 369-375

(2003)

DOI: 10.1016/S0921-4534(03)01086-4

show abstract

We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ∼40 nm and a very large aspect ratio (∼500). The diameter of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below Tc. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current (or voltage). The current induced breakdowns in the V–I characteristics may be explained by the formation of phase slip centers. Moreover, DC voltage driven measurements reveal the existence of a new S-shape behavior near the formation of these phase slip centers.

Lecture

Stefan Mátéfi-Tempfli

Nanoporous alumina templates for the growth of nanowires and nanotubes. Invited seminar.

In: Institute of Nuclear Research of the Hungarian Academy of Sciences

Debrecen, Ungarn

2003 (2003)

Lecture

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux

I-V characteristics of Pb and Sn superconducting nanowires.

In: March Meeting of the American Physical Society

Austin, TX, USA

03.-07.03.2003 (2003)

Lecture

L. Piraux
F. El Houssine
L. Vila
M. Darques
Stefan Mátéfi-Tempfli
S. Michotte

Transport and magnetism in nanowires.

In: 203rd Meeting of the Electrochemical Society

Paris, Frankreich

27.04.-02.05.2003 (2003)

Lecture

D. Vodolazov
F. Peeters
L. Piraux
Stefan Mátéfi-Tempfli
S. Michotte

Current-voltage characteristics of quasi-one-dimensional superconductors: An S-curve in the constant voltage regime.

In: International Scientific meeting BNV-SBP

Gent, Belgien

27.-28.05.2003 (2003)

Lecture

D. Vodolazov
F. Peeters
L. Piraux
Stefan Mátéfi-Tempfli
S. Michotte

Current-voltage characteristics of quasi-one-dimensional superconductors: An S-curve in the constant voltage regime.

In: The Joint 9th International Workshop on Vortex Dynamics and Vortex Matter (ESF)

Île d’Oléron, Frankreich

22.-27.07.2003 (2003)

Lecture

F. El Houssine
Stefan Mátéfi-Tempfli
A. Encinas
L. Piraux

Spin-dependent transport in ferromagnetic nanocontacts fabricated by electrodeposition in nanopores.

In: International Conference on Magnetism (ICM 2003)

Rom, Italien

27.07.-01.08.2003 (2003)

Journal article

A. Palnichenko
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
J.-P. Issi
L. Piraux
J.-C. Charlier

Selective formation of diamond-like carbon coating by surface catalyst patterning.

In: Carbon vol. 42 pg. 1879-1882

(2004)

DOI: 10.1016/j.carbon.2004.03.004

show abstract

Diamond-like carbon (DLC) materials are characterized by assemblies of varying ratios of sp3/sp2-bonded carbon and a lack of long range order of crystal structure. DLC is an extremely interesting industrial prospective material combining properties such as wear-, corrosion- and chemical-resistant qualities, resistance to stiction (i.e. a combination of stickness and friction), biocompatibility [1]. While silicon has been at the basis of modern electronics and the digital revolution, recent advances in microfabrication techniques have made possible the development of microscale devices that include different types of DLC coating [2]. Consequently, the process of controllable architecture of DLC coating is thus a major aspect for micro-electro-mechanical-systems manufacturing.

Journal article

S. Michotte
Stefan Mátéfi-Tempfli
L. Piraux
D. Vodolazov
F. Peeters

Condition for the occurrence of phase slip centers in superconducting nanowires under applied current or voltage.

In: Physical Review B: Condensed Matter and Materials Physics vol. 69 pg. 157001/1-157001/4

(2004)

DOI: 10.1103/PhysRevB.69.094512

show abstract

Experimental results on the phase slip process in superconducting lead nanowires are presented under two different experimental conditions: constant applied current or constant voltage. Based on these experiments we established a simple model which gives us the condition of the appearance of phase slip centers in a quasi-one-dimensional wire. The competition between two relaxations times (relaxation time of the absolute value of the order parameter τ|ψ| and relaxation time of the phase of the order parameter in the phase slip center τφ) governs the phase slip process. Phase slips, as periodic oscillations in time of the order parameter, are only possible if the gradient of the phase grows faster than the value of the order parameter in the phase slip center, or equivalently if τφ<τ|ψ|.

Lecture

S. Stroobants
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli
L. Piraux

Superconducting properties of Nb films with a periodic pinning array prepared by self-organising anodisation.

In: Workshop on Chemistry and Self-Assembly for Nanotechnology

Namur, Belgien

19.-20.02.2004 (2004)

Lecture

F. El Houssine
Stefan Mátéfi-Tempfli
L. Piraux

Développement de nouveaux matériaux pour l'électrodéposition de nanofils multicouches à magnétorésistance géante.

In: Colloque Louis Néel

Autrans, Frankreich

17.-19.03.2004 (2004)

Lecture

L. Piraux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Vila
M. Darques
F. El Houssine
S. Michotte

New routes for producing nanowires and nanotubes and their physical properties.

In: TNT 2004 International Conference

Segovia, Spanien

13.-17.09.2004 (2004)

Lecture

J. Mallet
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
K. Yu-Zhang
P. Searson
L. Piraux

Study of electrodeposited hard ferromagnetic CoPt nanowires.

In: The Fourth International Conference on Inorganic Materials

Antwerpen, Belgien

19.-21.09.2004 (2004)

Journal article

J. Mallet
K. Yu-Zhang
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux

Electrodeposited L10 CoxPt1-x nanowires.

In: Journal of Physics D: Applied Physics vol. 38 pg. 909-914

(2005)

DOI: 10.1088/0022-3727/38/6/020

show abstract

Arrays of face-centred cubic (fcc) CoxPt1 − x (0.45 < x < 0.55) nanowires were electrodeposited into thin film nanoporous alumina supported on a Si substrate. The heat treatment under specific conditions was then carried out in order to transform the fcc phase into the face-centred tetragonal or L10 ordered phase. The influence of both the phase transition and the temperature on the magnetic properties of CoxPt1−x nanowires has been studied. Coercive fields higher than 1 T (10 kOe) have been obtained at room temperature with ordered nanowires, 80 nm in diameter.

Journal article

S. Fusil
L. Piraux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Michotte
C. Saul
L. Pereira
K. Bouzehouane
V. Cros
C. Deranlot
J.-M. George

Nanolithography based contacting method for electrical measurements on single template synthesized nanowires.

In: Nanotechnology vol. 16 pg. 2936-2940

(2005)

DOI: 10.1088/0957-4484/16/12/036

show abstract

A reliable method enabling electrical measurements on single nanowires prepared by electrodeposition in an alumina template is described. This technique is based on electrically controlled nanoindentation of a thin insulating resist deposited on the top face of the template filled by the nanowires. We show that this method is very flexible, allowing us to electrically address single nanowires of controlled length down to 100 nm and of desired composition. Using this approach, current densities as large as 109 A cm−2 were successfully injected through a point contact on a single magnetic multilayered nanowire. This demonstrates that the technique is very promising for the exploration of electrical spin injection in magnetic nanostructures.

Journal article

E. Plocharska-Jankowska
M. Szpakowska
Stefan Mátéfi-Tempfli
O. Nagy

On the possibility of molecular recognition of taste substances studied by Gabor analysis of oscillations.

In: Biophysical Chemistry vol. 114 pg. 85-93

(2005)

DOI: 10.1016/j.bpc.2004.10.004

show abstract

A liquid membrane oscillator containing nitromethane as membrane material has been investigated. The influence of substances responsible for taste belonging to four classes (sweetness, saltiness, sourness and bitterness) on oscillation patterns of liquid membrane oscillators with cationic surfactant benzyldimethyltetradecylammonium chloride (BDMTAC) was examined. A new approach based on Gábor transformation is proposed for obtaining the power spectra of the observed oscillating signals and for establishing "fingerprints" of the investigated substances. It was shown that two-dimensional form of these power spectra might be used efficiently for this purpose.

Journal article

L. Piraux
A. Encinas
L. Vila
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
M. Darques
F. Elhoussine
S. Michotte

Magnetic and superconducting nanowires.

In: Journal of Nanoscience and Nanotechnology vol. 5 pg. 372-389

(2005)

DOI: 10.1166/jnn.2005.062

show abstract

This article is focused on the use of electrodeposition and of various nanoporous templates for the fabrication of metallic nanowires made from single metals (Ni, Co, Pb, Sn), alloys (NiFe, CoFe, CoPt), and multilayers (Co/Cu, NiFe/Cu). An overview is given of our recent studies performed on both magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also discussed.

Journal article

M. Szpakowska
O. Nagy
Stefan Mátéfi-Tempfli

Chemical kinetic approach to the mechanism of coupled transport of Cu(II) ions through bulk liquid membranes.

In: Journal of Physical Chemistry A vol. 109 pg. 10176

(2005)

DOI: 10.1021/jp055525y

show abstract

Transport of copper(II) ions through bulk liquid membranes is studied in various experimental conditions. The results obtained are analyzed by using the concepts and methods of chemical kinetics. This approach allowed kinetic equations to be established which are sufficiently general to account for a large variety of transport kinetics (steady or nonsteady state, first or zeroth order, diffusion or reaction controlled, reversible or irreversible), to identify clearly the rate-determining steps, and to propose a detailed mechanism at the molecular level. The important role played by the interfaces is also demonstrated.

Lecture

A. Palnichenko
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
J-P. Issi
L. Piraux
J-C. Charlier

Selective formation of diamond-like carbon coating by surface catalyst patterning.

In: 7th Biennal International Workshop, Fullerenes and Atomic Clusters (IWFAC’2005)

St. Petersburg, Russland

27.06.-01.07.2005 (2005)

Lecture

S. Xavier
E. Minoux
J-P. Schnell
P. Legagneux
Stefan Mátéfi-Tempfli
F. El Houssine
L. Piraux
E. Ferain
R. Legras

Growth and field emission properties of vertically aligned cobalt nanowire arrays.

In: European GDR on sciences and applications of nanotubes

Houffalize, Belgien

10.-13.10.2005 (2005)

Journal article

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
Z. Juhász
S. Biri
E. Fekete
I. Iván
F. Gáll
B. Sulik
G. Víkor
J. Pálinkás
N. Stolterfoht

Guided transmission of slow Ne6+ ions through the nanochannels of highly ordered anodic alumina.

In: Nanotechnology vol. 17 pg. 3915-3919

(2006)

DOI: 10.1088/0957-4484/17/15/050

show abstract

A highly ordered hexagonally close-packed nanochannels array was prepared using the self-ordering phenomena during a two-step anodization process of a high purity aluminium foil. The anodized aluminium oxide, with pore diameters of about 280 nm and interpore distances of about 450 nm was prepared as a suspended membrane of about 15 µm thickness on the aluminium frame to which it belongs. The Al2O3 capillaries were bombarded with 3 keV Ne6+ ions. The first results unambiguously show the existence of ion guiding observed at 5° and 7.5° tilt angles of the capillaries compared to the beam direction. To the best of our knowledge, such ion guiding effects of slow ions through hexagonally ordered nanochannels in alumina has not been reported previously.

Journal article

A. Vlad
M. Mátéfi-Tempfli
S. Faniel
V. Bayot
S. Melinte
L. Piraux
Stefan Mátéfi-Tempfli

Controlled growth of single nanowires within a supported alumina template.

In: Nanotechnology vol. 17 pg. 4873-4876

(2006)

DOI: 10.1088/0957-4484/17/19/016

show abstract

A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

Journal article

P. Lommens
P. Smet
de Mello Donega, C.
A. Meijerink
L. Piraux
S. Michotte
Stefan Mátéfi-Tempfli
D. Poleman
Z. Hens

Photoluminescence properties of Co2+-doped ZnO nanocrystals.

In: Journal of Luminescence vol. 118 pg. 245-250

(2006)

DOI: 10.1016/j.jlumin.2005.08.020

show abstract

We performed photoluminescence experiments on colloidal, Co2+-doped ZnO nanocrystals in order to study the electronic properties of Co2+ in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co2+ dopant. The spectral position and width of this emission does not depend on particle size or Co2+ concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co2+-emission band. We conclude that Co2+ ions are strongly localized in the ZnO host, making the formation of a Co2+d-band unlikely. Magnetic measurements revealed a paramagnetic behaviour.

Journal article

E. Plocharska-Jankowska
M. Szpakowska
Stefan Mátéfi-Tempfli
O. Nagy

A New Approach to the Spectral Analysis of Liquid Membrane Oscillators by Gabor Transformation.

In: Journal of Physical Chemistry B vol. 110 pg. 289-294

(2006)

DOI: 10.1021/jp0557870

show abstract

Liquid membrane oscillators very frequently have an irregular oscillatory behavior. Fourier transformation cannot be used for these nonstationary oscillations to establish their power spectra. This important point seems to be overlooked in the field of chemical oscillators. A new approach is presented here based on Gábor transformation allowing one to obtain power spectra of any kind of oscillations that can be met experimentally. The proposed Gábor analysis is applied to a liquid membrane oscillator containing a cationic surfactant. It was found that the power spectra are strongly influenced by the presence of various added substances.

Journal article

W. Vinckx
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Michotte
L. Piraux

Vortex pinning in superconducting Nb thin films deposited on nanoporous alumina templates.

In: European Physical Journal B: Condensed Matter and Complex Systems vol. 53 pg. 199-203

(2006)

DOI: 10.1140/epjb/e2006-00358-7

show abstract

We present a study of magnetization and transport properties of superconducting Nb thin films deposited on nanoporous aluminium oxide templates. Periodic oscillations in the critical temperature vs. field, matching effects in fields up to 700 mT and strongly enhanced critical currents were observed. These fields are considerably higher than those typical for periodic pinning arrays made by lithographic techniques, which reflects the benefits of nanostructuring superconductors by using self-organized growth. This method provides a periodic pinning potential with sub-100 nm spacing between the pinning centers, which enhances vortex pinning in broad field and temperature ranges.

Lecture

A. Milosavljević
Z. Pešić
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
G. Víkor
B. Marinković

Transmission of 50-200 eV Electrons through Highly Ordered Al2O3 Nanocapillaries..

In: 23rd Symposium on Physics of Ionized Gases – SPIG’2006

Kopaonik, Serbien

28.08.-01.09.2006 (2006)

Lecture

T. Blon
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
V. Cros
K. Bouzehouane
R. Guillemet
O. Copie
S. Fusil
C. Deranlot
L. Piraux

Injection de spin dans des nanofils magnétiques individuels électrodéposés dans des membranes d'alumine..

In: Journées de la Matière Condensée (JMC10)

Toulouse, Frankreich

28.08.-01.09.2006 (2006)

Lecture

Z. Juhász
G. Víkor
S. Biri
É. Fekete
I. Iván
K. Tőkési
E. Takács
J. Pálinkás
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
N. Stolterfoht
B. Sulik

Capillary guiding of slow Ne6+ ions in anodic alumina.

In: 16th International Workshop on Inelastic Ion-Surface Collisions (IISC-16)

Hernstein, Österreich

17.-22.09.2006 (2006)

Lecture

L. Piraux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
M. Darques
F. El Houssine
F. Menten
S. Michotte
M. Kinany-Alaoui El

Electrochemical fabrication of nanowires and their physical properties.

In: Congrès international sur la basse dimensionalité et la nanotechnologie

El Jadida, Marokko

01.-03.11.2006 (2006)

Journal article

T. Blon
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
L. Piraux
Fusil S.
Guillemet R.
Bouzehouane K.
C. Deranlot
V. Cros

Spin momentum transfer effects observed in electrodeposited Co/Cu/Co nanowires.

In: Virtual Journal of Nanoscale Science & Technology (NanoUnion)

(2007)

show abstract

Spin-transfer torque effects are reported in nanowires consisting in Co/Cu/Co trilayers electrodeposited on an anodic alumina template. Using a nanolithography process based on electrically controlled nanoindentation of the alumina template, we are able to investigate the spin transport properties of single nanowires at room temperature. For small applied magnetic fields, we have measured resistance changes above a critical direct-current (dc) injected current that corresponds to the change in resistance observed in the magnetoresistance curves at low current. We conclude that magnetic reversals are driven by a spin-polarized current. The critical current densities needed for the magnetization reversals are in the 107 A/cm2 range and the dependence of the critical currents with the applied field is consistent with the spin-transfer mechanism. For large applied magnetic fields, the differential resistance exhibits some peaks that we attribute to the onset of high-frequency excitations of the free-layer magnetization. According to the high density of electrodeposited nanowires in alumina templates, our results are promising for synchronized spin-transfer oscillators.

Journal article

A. Milosavljević
G. Víkor
Z. Pešić
Kolarž P.
Šević D.
B. Marinković
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux

Guiding of low-energy electrons by highly ordered Al2O3 nanocapillaries.

In: Physical Review A vol. 75 pg. 30901(4)

(2007)

DOI: 10.1103/PhysRevA.75.030901

show abstract

We report an experimental study of guided transmission of low-energy (200–350eV) electrons through highly ordered Al2O3 nanocapillaries with large aspect ratio (140nm diameter and 15μm length). The nanochannel array was prepared using self-ordering phenomena during a two-step anodization process of a high-purity aluminum foil. The experimental results clearly show the existence of the guiding effect, as found for highly charged ions. The guiding of the electron beam was observed for tilt angles up to 12°. As seen for highly charged ions, the guiding efficiency increases with decreasing electron incident energy. The transmission efficiency appeared to be significantly lower than observed for highly charged ions and, moreover, the intensity of transmitted electrons significantly decreases with decreasing impact energy.

Journal article

T. Blon
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
L. Piraux
Fusil S.
Guillemet R.
Bouzehouane K.
C. Deranlot
V. Cros

Spin momentum transfer effects observed in electrodeposited Co/Cu/Co nanowires.

In: Journal of Applied Physics vol. 102 pg. 103906(5)

(2007)

DOI: 10.1063/1.2812677

show abstract

Spin-transfer torque effects are reported in nanowires consisting in Co/Cu/Co trilayers electrodeposited on an anodic alumina template. Using a nanolithography process based on electrically controlled nanoindentation of the alumina template, we are able to investigate the spin transport properties of single nanowires at room temperature. For small applied magnetic fields, we have measured resistance changes above a critical direct-current (dc) injected current that corresponds to the change in resistance observed in the magnetoresistance curves at low current. We conclude that magnetic reversals are driven by a spin-polarized current. The critical current densities needed for the magnetization reversals are in the 107 A/cm2 range and the dependence of the critical currents with the applied field is consistent with the spin-transfer mechanism. For large applied magnetic fields, the differential resistance exhibits some peaks that we attribute to the onset of high-frequency excitations of the free-layer magnetization. According to the high density of electrodeposited nanowires in alumina templates, our results are promising for synchronized spin-transfer oscillators.

Journal article

L. Piraux
Renard K.
Guillemet R.
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
V.-A. Antohe
Fusil S.
Bouzehouane K.
V. Cros

Template-Grown NiFe/Cu/NiFe Nanowires for Spin Transfer Devices..

In: Nano Letters vol. 7 pg. 2563-2567

(2007)

DOI: 10.1021/nl070263s

show abstract

We have developed a new reliable method combining template synthesis and nanolithography-based contacting technique to elaborate current perpendicular-to-plane giant magnetoresistance spin valve nanowires, which are very promising for the exploration of electrical spin transfer phenomena. The method allows the electrical connection of one single nanowire in a large assembly of wires embedded in anodic porous alumina supported on Si substrate with diameters and periodicities to be controllable to a large extent. Both magnetic excitations and switching phenomena driven by a spin-polarized current were clearly demonstrated in our electrodeposited NiFe/Cu/ NiFe trilayer nanowires. This novel approach promises to be of strong interest for subsequent fabrication of phase-locked arrays of spin transfer nano-oscillators with increased output power for microwave applications.

Journal article

W. Vinckx
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Michotte
L. Piraux
X. Ye

High field matching effects in superconducting Nb porous arrays catalyzed from anodic alumina templates.

In: Physica C: Superconductivity and its Applications vol. 459 pg. 5-10

(2007)

DOI: 10.1016/j.physc.2007.04.194

show abstract

Vortex pinning in a superconducting Nb thin film deposited on an anodically grown alumina template is investigated. Anodic oxidation of aluminium layers permits under specific conditions the formation of highly ordered porous alumina, a membrane-like structure consisting of triangular arrays of parallel pores. Its pore diameter and interpore distance are set by careful tuning of the anodization parameters. A superconducting Nb thin film is deposited directly onto the alumina film. The porous alumina acts as a template and it allows Nb to form a periodic pinning array during its growth. Pinning force vs. field measurements derived from magnetization measurements, show matching effects in fields up to 1 T. We demonstrate that the anodic alumina template with 50 nm interpore spacing provides enhanced vortex pinning in a large field and temperature range.

Contribution

Stefan Mátéfi-Tempfli

Nanostructures Grown Via Electrochemical Template Methods: Synthesis, Measurements and Applications (Chapter 10).

In: Leading edge nanotechnology research developments. pg. 235-256

Eds.:
D. Sabatini

Nova Science Publishers New York

(2007)

Journal article

A. Milosavljević
G. Víkor
Z. Pešić
Kolarž P.
Šević D.
B. Marinković
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux

Guiding of low-energy electrons by highly ordered Al2O3 nanocapillaries.

In: Virtual Journal of Nanoscale Science & Technology (NanoUnion) vol. 15

(2007)

Lecture

M. Milosavljevic
G. Víkor
Z. Pešić
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
P. Kolarž
D. Šević
B. Marinković

Guided transmission of low-energy electrons by highly ordered Al2O3 nanocapillaries.

In: 9th European Conference on Atoms Molecules & Photons (ECAMP 9)

Kreta, Griechenland

06.-11.05.2007 (2007)

Lecture

A. Vlad
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Faniel
V. Bayot
L. Piraux
S. Melinte

Controlled growth of single nanowires within a supported aluminium template.

In: European Materials Research Society (E-MRS) Spring Meeting

Strasbourg, Frankreich

28.05.-01.06.2007 (2007)

Lecture

A. Vlad
M. Mátéfi-Tempfli
S. Faniel
N. Reckinger
A. Crahay
B. Olbrechts
V. Bayot
L. Piraux
Melinte S.
Stefan Mátéfi-Tempfli

Controlled growth of single nanowires within supported alumina template: towards circuit Integration.

In: Leuven Nano-Conference – LNC'07

Leuven, Belgien

05.-06.06.2007 (2007)

Lecture

L. Piraux
K. Renard
R. Guillemet
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
V.-A. Antohe
S. Fusil
Bouzehouane K.
V. Cros

Template-Grown Magnetic Nanowires for Spin Transfer Devices.

In: International Conference on Nanoscale Magnetism (ICNM-2007)

Istanbul, Türkei

25.-29.06.2007 (2007)

Lecture

Stefan Mátéfi-Tempfli

Nanowires and nanostructures fabrication using template methods: A step forward to real devices combining electrochemical synthesis with lithographic techniques. Invited speaker.

In: International Conference on Optical, Optoelectronic and Photonic Materials and Applications (ICOOPMA07)

London, Großbritannien

Juli 2007 (2007)

Lecture

B. Sulik
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
Z. Juhász
S. Biri
E. Fekete
I. Iván
F. Gáll
G. Víkor
J. Pálinkás
N. Stolterfoht

Guiding of few keV ions in insulator nanocapillaries.

In: Theoretical and Computational Physics Seminars

The Queen's University of Belfast Belfast, Nordirland, Großbritannien

03.07.2007 (2007)

Lecture

V.-A. Antohe
Stefan Mátéfi-Tempfli
A. Vlad
D. Serban
M. Mátéfi-Tempfli
S. Melinte
L. Piraux

Nanowires Arrays Used For Biosensors with High Active Surfaces..

In: Leuven Nano-Conference – LNC'07

Leuven, Belgien

05.-06.07.2007 (2007)

Lecture

Z. Juhász
G. Víkor
S. Biri
É. Fekete
I. Iván
K. Tőkési
E. Takács
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
J. Pálinkás
B. Sulik

Ion-insulator interactions inside ion-guiding nanocapillaries..

In: International Symposium on Ion Atom Collisions (XX ISIAC)

Agios Nikolaos, Kreta, Griechenland

01.-04.08.2007 (2007)

Lecture

Stefan Mátéfi-Tempfli

Fabrication of nanowires and nanostructures. Measurements and applications. Keynote lecture. Chair of the session "Nanostructured materials I".

In: International Workshop on Smart Materials & Structures

Kiel

August 2007 (2007)

Lecture

J. Vanacken
W. Vinckx
V. Moshchalkov
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Michotte
L. Piraux
Ye X.

Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays..

In: Joint ESF and JSPS Conference on Vortex Matter in Nanostructured Superconductors (VORTEX V)

Rhodos, Griechenland

08.-14.09.2007 (2007)

Journal article

V.-A. Antohe
A. Radu
S. Yunus
A. Attout
P. Bertrand
M. Mátéfi-Tempfli
L. Piraux
Stefan Mátéfi-Tempfli

A versatile method to grow localized arrays of nanowires for highly sensitive capacitive devices.

In: Journal of Optoelectronics and Advanced Materials vol. 10 pg. 2936-2941

(2008)

show abstract

We propose a new approach to increase the detection efficiency of the capacitive sensing devices, by growing vertically aligned nanowires arrays, localized and confined on small interdigited electrodes structures. The metallic tracks are made using optical lithography, and the nanowires are realized by electrochemical synthesis in nanoporous materials (i.e. supported alumina templates). By controlling the preparation conditions, both their positions and pitches can be easily tuned, as well as their geometrical design (i.e. diameters between 5 – 350 nm and lengths between 150 nm – 10 μm). Based on these considerations, a capacitive sensor structure with high active surface is sensitized with polyaniline, for pH detection. Reported data show that the sensitivity of the sensor is substantially improved by using nanowires arrays.

Journal article

A. Vlad
M. Mátéfi-Tempfli
V.-A. Antohe
S. Faniel
N. Reckinger
B. Olbrechts
A. Crahay
V. Bayot
L. Piraux
S. Melinte
Stefan Mátéfi-Tempfli

Nanowire-decorated Microscale Metallic Electrodes.

In: Small vol. 4 pg. 557-560

(2008)

DOI: 10.1002/smll.200700724

show abstract

One of the challenging aspects of science and technology on ananometer-scale is the precise three-dimensional control ofnano-objects. Scanning probe microscopy manipulation,magnetic- or electric-field alignment and lithography-basedtechniques are only a few of the techniques that have beenreported so far.[1]Nevertheless, most of these techniques arestill being developed and their integration for devicefabrication represents a real challenge for the scientificcommunity. Within this context, nanowires and nanotubesare of great interest because they lie between the macroscopicand atomic scales. The ability to fabricate and manipulate suchobjects in a reliable manner on a large scale will foster their usein electronic, photonic, and sensing applications.[2]Template-based methods have been successfully used for nanowirefabrication as they allow the realization of complex organic/inorganic nanostructures.[3]To date, nanoporous anodicalumina oxide (AAO) made by the electrochemical oxidationof aluminum has been extensively used because it provides agood platform for the development of various nanostructures.This interest originates from the fact that AAO membranes,having a high density of nanopores (up to 1012cm2), are easilyproduced over large areas with variable thicknesses.[4]More-over, a good chemical and mechanical stability combined withinteresting electrical properties make AAO membranes goodcandidates for nanowire fabrication. However, the use of suchnanostructures as passive or active components in emergingelectronic devices requires smartly engineered arrays ofnanowires with well defined position and pitch.

Journal article

J. Vanacken
W. Vinckx
V. Moshchalkov
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Michotte
L. Piraux
Ye X.

Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays.

In: Physica C: Superconductivity and its Applications vol. 468 pg. 585-588

(2008)

DOI: 10.1016/j.physc.2007.11.070

show abstract

Being the exponent of the so-called “bottom-up” approach, self-assembled structures are now-a-days attracting a lot of attention in the fields of science and technology. In this work, we show that nanoscale self-assembled arrays used as templates can provide periodic modulation in superconducting thin films by studying their vortex pinning properties. In this work advantage was made of the fact that self-organized assemblies of identical units such as colloidal crystals and anodic aluminum oxide provide extended periodic topographic surfaces. By directly growing Nb on top of these self-assembled arrays, the templating effect was exploited in order to achieve triangular and honeycomb arrays of pinning centers in thin superconducting films. We show experimentally that periodic matching is achieved in both systems at magnetic fields, well above those present in lithographically prepared pinning arrays (up to 1 T!). Furthermore, we demonstrate in the case of anodic aluminum oxide that the presence of porous antidots in Nb not only provides strongly increased critical currents but also conserves matching at temperatures well below the critical temperature. The studies conducted on these systems indicate that the method of template growth might be considered as a viable alternative for the incorporation of periodic pinning arrays in superconducting applications of today and the future.

Journal article

D. Magnin
V. Callegari
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
K. Glinel
A. Jonas
S. Demoustier-Champagne

Functionalization of Magnetic Nanowires by Charged Biopolymers.

In: Biomacromolecules vol. 9 pg. 2517-2522

(2008)

DOI: 10.1021/bm8005402

show abstract

We report on a facile method for the preparation of biocompatible and bioactive magnetic nanowires. The method consists of the direct deposition of polysaccharides by layer-by-layer (LbL) assembly onto a brush of metallic nanowires obtained by electrodeposition of the metal within the nanopores of an alumina template supported on a silicon wafer. Carboxymethylpullulan (CMP) and chitosan (CHI) multilayers were grown on brushes of Ni nanowires; subsequent grafting of an enzyme was performed by conjugating free amine side groups of chitosan with carboxylic groups of the enzyme. The nanowires are finally released by a gentle ultrasonic treatment. Transmission electron microscopy, electron energy-dispersive loss spectroscopy, and x-ray photoelectron spectroscopy indicate the formation of an homogeneous coating onto the nickel nanowires when one, two, or three CMP/CHI bilayers are deposited. This easy and efficient route to the biochemical functionalization of magnetic nanowires could find widespread use for the preparation of a broad range of nanowires with tailored surface properties.

Journal article

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux

Characterization of nanopores ordering in anodic alumina.

In: Thin Solid Films vol. 516 pg. 3735-3740

(2008)

DOI: 10.1016/j.tsf.2007.06.076

show abstract

A simple characterization method of the ordering of the nanopores is described for nanoporous anodized aluminium oxides. The method starts with image analysis on scanning electron microscopy representations for the purpose to find repetitive shapes and their centres, i.e. nanopores. Then triangles defined by coordinates of the centres are identified by Delaunay tessellation. Evaluation of the ordering degrees is then performed by a two-level analysis of the triangles. We define order parameters for triangular and hexagonal organization levels and show through typical examples that they are highly sensitive on ordering.

Journal article

S. Xavier
Stefan Mátéfi-Tempfli
E. Ferain
S. Purcell
S. Enouz-Védrenne
L. Gangloff
E. Minoux
L. Hudanski
P. Vincent
J-Ph. Schnell
D. Pribat
L. Piraux
P. Legagneux

Stable field emission from arrays of vertically aligned free-standing metallic nanowires.

In: Nanotechnology vol. 19 pg. 215601(7)

(2008)

DOI: 10.1088/0957-4484/19/21/215601

show abstract

We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost fabrication and large surfaces. This technique offers an excellent control of the orientation, shape and nanowires density. It is applied to fabricate field emission arrays with a good control of the emission site density. We have prepared Co, Ni, Cu and Rh nanowires with a height of 3 µm, a diameter of 80 nm and a density of ~107 cm−2. The electron field emission measurements and total energy distributions show that the as-grown nanowires exhibit a complex behaviour, first with emission activation under high field, followed by unstable emission. A model taking into account the effect of an oxide layer covering the nanowire surface is developed to explain this particular field emission behaviour. Finally, we present an in situ cleaning procedure by ion bombardment that collectively removes this oxide layer, leading to a stable and reproducible emission behaviour. After treatment, the emission current density is ~1 mA cm−2 for a 30 V µm−1 applied electric field.

Lecture

L. Piraux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
V.-A. Antohe

Template-grown magnetic nanowires for spin-trasnfer devices.

In: Workshop on Recent Trends in Nanomagnetism

Katholieke Universiteit Leuven Leuven, Belgien

Februar 2008 (2008)

Lecture

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
P. Kolarž
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
B. Marinković

Guiding of low-energy electrons through insulating nanocapillaries.

In: Electron Controlled Chemical Lithography 2008 Meeting (ECCL2008)

Lissabon, Portugal

12.-16.03.2008 (2008)

Lecture

Z. Juhász
B. Sulik
G. Víkor
S. Biri
I. Iván
K. Tőkési
E. Takács
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
J. Pálinkás

MCP Images of Ions Transmitted Through Ion Guiding Alumina Capillaries.

In: 4th Conference on Elementary Processes in Atomic Systems

Cluj-Napoca, Rumänien

18.-20.06.2008 (2008)

Lecture

Stefan Mátéfi-Tempfli

Nanoporous alumina, a key material for nanowires and nanostructures fabrication. Invited lecture. Chair of the session "Condensed matter physics and applications".

In: 9th International Balkan Workshop on Applied Physics

Constanta, Rumänien

Juli 2008 (2008)

Lecture

V.-A. Antohe
A. Radu
S. Yunus
M. Mátéfi-Tempfli
A. Dutu
A. Vlad
S. Melinte
L. Piraux
Stefan Mátéfi-Tempfli

Fabrication of Localized Nanowires Arrays used for Increasing the Sensitivity in pH Measuring Applications.

In: 9th Inernational Balkan Workshop on Applied Physics

Constanta, Rumänien

07.-09.07.2008 (2008)

Lecture

X. Hallet
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
L. Piraux
W. Vinckx
J. Vanacken
V. Moshchalkov

Artificial Pinning Centers Using Ordered Nanoporous Alumina Templates..

In: Workshop on Superconducting Nanosystems

Katholieke Universiteit Leuven Heverlee, Belgien

24.07.2008 (2008)

Lecture

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
B. Marinković

Transmission of electrons through Al2O3 nanocapillaries in the energy range 2-250 eV..

In: 24th International Symposium on the Physics of Ionized Gases

Novi Sad, Serbien

25.-29.08.2008 (2008)

Lecture

X. Hallet
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
W. Vinckx
J. Vanacken
V. Moshchalkov

Artificial Pinning Centers Using Ordered Nanoporous Alumina Templates: Time Effect on Magnetization Curves of Nanostructured Nb Films..

In: International Conference on Superconductivity and Magnetism (ICSM 2008)

Side-Antalya, Türkei

25.-29.08.2008 (2008)

Lecture

X. Hallet
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
L. Piraux
W. Vinckx
J. Vanacken
V. Moshchalkov

Artificial Pinning Centers Using Ordered Nanoporous Alumina Templates..

In: Congress on Materials Science and Engineering (MSE08)

Nürnberg

01.-04.09.2008 (2008)

Lecture

V.-A. Antohe
A. Dutu
A. Vlad
M. Mátéfi-Tempfli
S. Yunus
L. Piraux
Stefan Mátéfi-Tempfli

Fabrication of Localized Naowires Arrays Used for Sensing Applications, by Combining Electrochemical Synthesis with Lithographic Techniques. A.

In: Congress on Materials Science and Engineering (MSE08)

Nürnberg

01.-04.09.2008 (2008)

Lecture

A. Vlad
M. Mátéfi-Tempfli
V.-A. Antohe
V. Bayot
L. Piraux
S. Melinte
Stefan Mátéfi-Tempfli

Confined Growth of Nanowires within Supported Alumina Templates for Large Scale Circuit Integration.

In: Congress on Materials Science and Engineering (MSE08)

Nürnberg

01.-04.09.2008 (2008)

Lecture

M. Finazzi
M. Celebrano
P. Biagioni
M. Savoini
B. Echt
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Duò
G. Cerullo

Two-photon photoluminescence efficiency in gold nanowires: unexpected dependence on pulse duration..

In: 10th International Conference on Near-field Optics, Nanophotonics and Related Techniques

Buenos Aires, Argentinien

01.-05.09.2008 (2008)

Lecture

Stefan Mátéfi-Tempfli

Miniaturizing bio-sensors toward nanoscales. Keynote lecture. Chair of the session "Nanostructured Materials: Science and Technology : Bio-active Nanomaterials".

In: Congress on Materials Science and Engineering (MSE08)

Nürnberg

September 2008 (2008)

Lecture

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
B. Marinković

Transmission of low-energy electrons through insulating nanocapillaries.

In: ESF-FWF Conference in Partnership with LFUI: "Chemical Control with Electrons and Photons"

Obergurgl, Österreich

22.-27.11.2008 (2008)

Lecture

L. Piraux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
M. M. Darques
R. Guillemet
S. Fusil
K. Bouzehouane
V. Cros

Magnetotransport on single magnetic nanowires.

In: M-SNOWS 2008, Magnetic Single Nano-Object Workshop and School

Nancy, Frankreich

23.-28.11.2008 (2008)

Journal article

X. Hallet
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
S. Michotte
J. Vanacken
V. Moshchalkov

Artificial pinning centers using the barrier layer of ordered nanoporous alumina templates.

In: Journal of Physics: Conference Series vol. 153 pg. 012013(7)

(2009)

DOI: 10.1088/1742-6596/153/1/012013

show abstract

The barrier layer of self-ordered anodized aluminium oxide, which is grown from an aluminium foil, has been revealed by a selective chemical etching of the remaining aluminium. The surface obtained in this way consists of a triangular lattice of bumps with 100nm spacing, and heights of approximately 50nm. Using this surface as a template for controlling the pinning in thin superconducting films, superconducting Nb was deposited with different thicknesses and under different deposition angles. The evaporation under a 30° angle shows an asymmetric pinning potential composed of two triangular lattices having different pinning strengths. Matching effects are observed up to 1T. Matching effects are also maintained at relatively low temperature.

Journal article

Z. Juhász
B. Sulik
S. Biri
I. Iván
K. Tőkési
É. Fekete
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
G. Víkor
E. Takács
J. Pálinkás

Ion Guiding in Alumina Capillaries: MCP Images of the Transmitted Ions.

In: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms vol. 267 pg. 321-325

(2009)

DOI: 10.1016/j.nimb.2008.10.017

show abstract

Transmission of a few keV impact energy Ne6+ ions through capillaries in anodic alumina membranes has been studied with different ion counting methods using an energy dispersive electrostatic spectrometer, a multichannel plate (MCP) array and sensitive current-measurement. In the present work, we focus our attention to the measurements with the MCP array. The alumina capillaries were prepared by electro-chemical oxidation of aluminium foils. For the present experiments guiding of 3-6 keV Ne6+ ions has been studied in two samples with capillary diameter of about 140 nm and 260 nm and with capillary length of about 15 μm. At these energies, the ions have been efficiently guided by the capillaries up to few degrees tilt angle. In this work, we compare the results obtained by the energy dispersive spectrometer to those studied by the MCP array.

Journal article

X. Hallet
M. Mátéfi-Tempfli
S. Michotte
L. Piraux
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli

High field matching effects in NbN induced by a dense ferromagnetic nanowires array grown in a nanoporous alumina template.

In: Applied Physics Letters vol. 95 pg. 252503(3)

(2009)

DOI: 10.1063/1.3276557

show abstract

Dense arrays of ordered ferromagnetic nanowires have been used to create periodic magnetic pinning centers in thin superconducting NbN films. The nanowires were electrodeposited in a highly ordered porous alumina membrane and the thin NbN film was deposited on top of the perpendicularly oriented magnetic nanowires. Matching effects have been observed up to 2.5 T (11th matching field) and are maintained at low temperature. An appreciable enhancement of the superconducting properties is observed. At low fields, a hysteretic behavior in the magnetoresistance is found, directly related to the magnetization processes of arrays of interacting single domain ferromagnetic nanowires.

Journal article

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli

Vertically aligned nanowires on flexible silicone using supported alumina template prepared by pulsed anodization.

In: Advanced Materials vol. 21 pg. 4005-4010

(2009)

DOI: 10.1002/adma.200900344

show abstract

Carpets of vertically aligned nanowires on flexible substrates are successfully realized by a template method. Applying special pulsed anodization conditions, defect‐free nanoporous alumina structures supported on polydimethylsiloxane (PDMS), a flexible silicone elastomer, are created. By using this template with nanopores ending on a conducting underlayer, a high‐density nanowire array can be simply grown by direct DC‐electrodeposition on the top of the silicone rubber.

Contribution

Stefan Mátéfi-Tempfli

Leading Edge Nanotechnology Research Developments.

In: Nanotechnology Research Collection. 2009/2010 (Nanotechnology Science and Technology)

Eds.:
J. Ling

Nova Science Publishers Hauppauge, NY

(2009)

Journal article

V.-A. Antohe
A. Radu
M. Mátéfi-Tempfli
A. Attout
S. Yunus
P. Bertrand
C. Dutu
A. Vlad
S. Melinte
Stefan Mátéfi-Tempfli
L. Piraux

Nanowire-Templated Microelectrodes for High-Sensitivity pH Detection.

In: Virtual Journal of Nanoscale Science & Technology (NanoUnion) vol. 19

(2009)

show abstract

A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved by changing only the thickness of the functional layer.

Journal article

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
A. Vlad
V.-A. Antohe
L. Piraux

Nanowires and nanostructures fabrication using template methods: A step forward to real devices combining electrochemical synthesis with lithographic techniques.

In: Journal of Materials Science: Materials in Electronics vol. 20 pg. 249-254

(2009)

Journal article

V.-A. Antohe
A. Radu
M. Mátéfi-Tempfli
A. Attout
S. Yunus
P. Bertrand
C. Dutu
A. Vlad
S. Melinte
Stefan Mátéfi-Tempfli
L. Piraux

Nanowire-Templated Microelectrodes for High-Sensitivity pH Detection.

In: Applied Physics Letters vol. 94 pg. 073118(3)

(2009)

DOI: 10.1063/1.3089227

show abstract

A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved by changing only the thickness of the functional layer.

Journal article

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
Šević D.
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
B. Marinković

Low-energy electron transmission through high aspect ratio Al2O3 nanocapillaries..

In: EPL - A Letters Journal Exploring the Frontiers of Physics vol. 86 pg. 23001(6)

(2009)

DOI: 10.1209/0295-5075/86/23001

show abstract

Electron transmission through insulating Al2O3 nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2–120 eV). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined with respect to the capillary axis. On the other hand, the intensity of elastically transmitted electrons significantly varies with the alteration of electron energy and tilt angle. In addition, we measured an energy distribution of electrons transmitted both in the straightforward direction and at large tilt angle. The measured spectra show that inelastic processes dominate and, in particular, a large amount of low-energy electrons. These low-energy electrons can be either inelastically scattered projectiles or secondary electrons emitted within the capillaries. Furthermore, a change of the tilt angle appears to influence significantly only the intensity of the elastic transmission. The present results suggest a more complex nature of low-energy electron transport through insulating nanocapillaries than proposed for positive ions.

Contribution

Stefan Mátéfi-Tempfli

Nanostructures Grown Via Electrochemical Template Methods (Chapter).

In: Encyclopedia of Nanotechnology. pg. 459-481

Eds.:
E. Carlson

Nova Science Publishers New York

(2009)

Journal article

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux

Fabrication of nanowires and nanostructures: combining template synthesis with patterning methods.

In: Applied Physics A - Materials Science and Processing vol. 96 pg. 603-608

(2009)

DOI: 10.1007/s00339-009-5085-6

show abstract

We report on different approaches that we have adopted and developed for the fabrication of nanowires and nanostructures. Methods based on template synthesis and on self organization seem to be the most promising for the fabrication of nanomaterials and nanostructures due to their easiness and low cost. The development of a supported nanoporous alumina template and the possibility of using this template to combine electrochemical synthesis with lithographic methods open new ways for the fabrication of complex nanostructures. The numerous advantages of the supported template and its compatibility with microelectronic processes make it an ideal candidate for further integration into large-scale fabrication of various nanowire-based devices.

Journal article

P. Biagioni
M. Celebrano
M. Savoini
G. Grancini
D. Brida
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Duò
B. Hecht
G. Cerullo
M. Finazzi

Dependence of the two-photon photoluminescence yield of gold nanostructures on the laser pulse duration.

In: Physical Review B vol. 80 pg. 045411(5)

(2009)

DOI: 10.1103/PhysRevB.80.045411

show abstract

Two-photon photoluminescence (TPPL) from gold nanostructures is becoming one of the most relevant tools for plasmon-assisted biological imaging and photothermal therapy as well as for the investigation of plasmonic devices. Here we study the yield of TPPL as a function of the temporal width δ of the excitation laser pulses for a fixed average power. In the δ>1 ps regime, the TPPL yield decreases as δ is increased, while for shorter pulse widths it becomes independent of δ and, consequently, of the laser-pulse peak power. This peculiar dynamics is understood and modeled by considering that two-photon absorption in Au is a two-step process governed by the lifetime of the metastable state populated by the first photon absorption.

Journal article

X. Hallet
M. Mátéfi-Tempfli
L. Piraux
S. Michotte
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli

Quasi-hexagonal vortex pinning lattice using anodized aluminum oxide nanotemplates..

In: Small vol. 5 pg. 2413-2416

(2009)

show abstract

The bottom barrier layer of well‐ordered nanoporous alumina membranes reveals a previously unexploited nanostructured template surface consisting of a triangular lattice of hemispherical nanoscale bumps. Quasi‐hexagonal vortex‐pinning lattice arrays are created in superconducting Nb films deposited onto this template (see image). Matching effects are preserved at higher magnetic fields and lower temperatures when compared to holes on the top face.

Lecture

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
B. Marinković

Low-Energy Electron Transport through High Aspect Ratio Al2O3 Nanocapillaries..

In: 17th Symposium on Applications of Plasma Processes (SAPP)

Liptovský Ján, Slovakia

17.-22.01.2009 (2009)

Lecture

Stefan Mátéfi-Tempfli

Arrays of localized nanowires down to single ones on solid and on flexible substrates using supported nanoporous alumina templates. Invited lecture. Chair of the session "Applications as Sensors II".

In: 1st International Conference on Nanostructured Materials and Nanocomposites

Kottayam, Indien

April 2009 (2009)

Lecture

A. Vlad
C. Dutu
M. Mátéfi-Tempfli
S. Melinte
Stefan Mátéfi-Tempfli

Statistical Patterning: A General Route for Nanoporous Templates Structuring with Single-nanopore Resolution.

In: MRS2009 Spring Meeting: Architectured Multifunctional Materials

San Francisco, CA, USA

14.-16.04.2009 (2009)

Lecture

V.-A. Antohe
A. Radu
M. Mátéfi-Tempfli
A. Attout
S. Yunus
P. Bertrand
C. Dutu
S. Melinte
L. Piraux
Stefan Mátéfi-Tempfli

Nanowire-Templated Microelectrodes, for Highly-Sensitive pH Detecting Devices.

In: 10th International Balkan Workshop on Applied Physics (IBWAP 2009)

Constanta, Rumänien

06.-08.07.2009 (2009)

Lecture

V.-A. Antohe
A. Radu
M. Mátéfi-Tempfli
A. Attout
S. Yunus
P. Bertrand
C. Dutu
S. Melinte
L. Piraux
Stefan Mátéfi-Tempfli

Nanowire-Templated Microelectrodes, for Highly-Sensitive pH Detecting Applications.

In: 6th International Conference on Nanosciences & Nanotechnologies (N&N 09)

Thessaloniki, Griechenland

12.-15.07.2009 (2009)

Lecture

X. Hallet
M. Mátéfi-Tempfli
L. Piraux
S. Michotte
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli

High field matching effects in NbN induced by ferromagnetic nanowires array grown in highly ordered nanoporous alumina template.

In: Workshop on vortex dynamics in mesoscopic superconductors

Leuven, Belgien

14.07.2009 (2009)

Lecture

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
S. Melinte
A. Vlad

Statistics and single element processing in nanoporous templates..

In: 14th International Conference on Modulated Semiconductor structures (MSS-14)

Kobe, Japan

19.-24.07.2009 (2009)

Lecture

D. Darques
A. Dussaux
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
J. Grollier
V. Cros
Bouzehouane K.
S. Fusil
R. Guillemet
L. Piraux
A. Fert

Microwave emission in electrodeposited spin transfer oscillators connected in series.

In: International Conference on Magnetism - ICM 2009

Karlsruhe

26.-31.07.2009 (2009)

Lecture

Stefan Mátéfi-Tempfli

Arrays of vertically aligned nanowires on flexible substrate by using supported nanoporous alumina. Invited lecture. Chair of the session "Nanostructures and Thin Films". Member of the advisory board..

In: 3rd International Workshop on Smart Materials & Structures

Kiel

August 2009 (2009)

Lecture

X. Hallet
M. Mátéfi-Tempfli
L. Piraux
S. Michotte
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli

High field matching effects in FM-SC heterostructures.

In: 6th International Conference on Vortex Matter in Nanostructured Superconductors (VORTEX VI)

Rhodos, Griechenland

16.-24.09.2009 (2009)

Journal article

I. Rajta
G.A.B. Gál
S. Szilasi
Z. Juhász
S. Biri
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli

Nanochannel alignment analysis by scanning transmission ion microscopy.

In: Nanotechnology vol. 21 pg. 295704(4)

(2010)

DOI: 10.1088/0957-4484/21/29/295704

show abstract

In this paper a study on the ion transmission ratio of a nanoporous alumina sample is presented. The sample was investigated by scanning transmission ion microscopy (STIM) with different beam sizes. The hexagonally close-packed Al2O3 nanocapillary array, realized as a suspended membrane of 15 µm thickness, had pore diameters of ~ 215 nm and spacing of ~ 450 nm. When the proton beam size was limited to a single domain, a peak transmission ratio of 19% was observed as is expected from the geometry (~19–20%). This result points out an almost perfectly parallel alignment of the capillaries within one domain. However, for larger beam scanning areas (sampling multiple domains) the transmission ratio was reduced to 5%. The STIM analysis over an area larger than the typical domain size revealed an overall capillary angular spread of ~ 2°.

European Campus Rottal-Inn

Journal article

A. Vlad
S. Melinte
M. Mátéfi-Tempfli
L. Piraux
Stefan Mátéfi-Tempfli

Vertical nanowire architectures: Statistical processing of porous templates towards discrete nanochannel integration.

In: Small vol. 6 pg. 1974-1980

(2010)

DOI: 10.1002/smll.201000723

show abstract

Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide rigorous selection rules for measuring well‐defined numbers of nanowires located into nanoporous templates, and provides a conceptual framework for the fabrication of nanowire‐based crossbar latches.

Lecture

Stefan Mátéfi-Tempfli

Nanofabrication. Session chair.

In: 3rd IEEE International NanoElectronics Conference

Hong Kong, China

January 2010 (2010)

Lecture

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
L. Piraux
S. Melinte
A. Vlad

Statistical Processing of Nanoporous Templates with High-Yield Single-Pore Resolution..

In: 3rd IEEE International NanoElectronics Conference

Hong Kong, China

03.-08.01.2010 (2010)

Lecture

Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli

Carpet of Nanowires on Flexible Silicone Substrate..

In: 3rd IEEE International NanoElectronics Conference

Hong Kong, China

03.-08.01.2010 (2010)

Lecture

V.-A. Antohe
A. Radu
M. Mátéfi-Tempfli
A. Attout
S. Yunus
P. Bertrand
C. Dutu
S. Melinte
L. Piraux
Stefan Mátéfi-Tempfli

Highly Sensitive pH Detectors Based on Localized Nanowire Arrays.

In: 34th International Conference and Exposition on Advanced Ceramics and Composites: 4th International Symposium on Nanostructured Materials and Nanotechnology (ICACC)

Daytona Beach, FL, USA

24.-29.01.2010 (2010)

Lecture

Stefan Mátéfi-Tempfli

Electrochemical template synthesis of nanostructures on solid and on flexible substrates. Invited seminar.

In: Institute for Pure and Applied Chemistry

Carl von Ossietzky Universität Oldenburg Oldenburg

März 2010 (2010)

Lecture

Stefan Mátéfi-Tempfli

Template synthesized nanostructures on solid and flexible substrates for bio-interfaces and sensing applications. Invited talk and chair of the session "Membranes".

In: International Conference on Nanomaterials: Synthesis, Characterization and Applications

Mahatma Gandhi University Priyadharshini Hills, Kottayam, Indien

April 2010 (2010)

Lecture

X. Hallet
M. Mátéfi-Tempfli
L. Piraux
J. Vanacken
V. Moshchalkov
Stefan Mátéfi-Tempfli

Continuously tunable high magnetic field-induced superconductivity In NbN obtained by template grown ferromagnetic nanowires array.

In: International Conference on Superconductivity and Magnetism (ICSM 2010)

Antalya, Türkei

25.-30.04.2010 (2010)

Lecture

I. Rajta
G.A.B. Gál
S. Szilasi
Z. Juhász
S. Biri
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli

Scanning Transmission Ion Microscopy on Al2O3 Nanocapillary Arrays..

In: 12th International Conference on Nuclear Microprobe Technology and Applications (ICNMTA 2010)

Leipzig

26.-30.06.2010 (2010)

Lecture

Stefan Mátéfi-Tempfli

Electrochemical template synthesis of nanostructures on solid and on flexible substrates. Invited talk.

In: Fraunhofer Institute for Manufacturing Technology and Advanced Materials

Bremen

Oktober 2010 (2010)

Journal article

S. Habouti
M. Mátéfi-Tempfli
C.-H. Solterbeck
M. Es-Souni
Stefan Mátéfi-Tempfli

Self-standing corrugated Ag and Au-Nanorods as plasmonic substrates.

In: Journal of Materials Chemistry vol. 21 pg. 6269-6273

(2011)

show abstract

We use home-made Si-supported anodized alumina thin film templates for the electrodeposition of large area self-standing Ag- and Au-nanorod (Au-NR) arrays. The deposition conditions chosen, i.e. electrolyte composition and deposition voltage, lead to a corrugated rod morphology, particularly for Au-NRs. Instantaneous nucleation followed by diffusion-controlled growth are thought to be the dominating mechanism for the morphology observed. Diffuse reflectance spectra show specific behaviours of Ag- and Au-NRs with longitudinal and transverse plasmon resonance modes and additional modes for Ag-NRs. The activity of the NR arrays as substrates for molecular detection using Raman scattering and Rhodamine 6G (R6G) as a model dye strongly depends on noble metal. R6G concentrations down to 1 pM are detected on the corrugated arrays yielding an effective enhancement factor (EF) of approximately 2 × 1010 for Ag-NRs and 1 × 109 for Au-NRs. The latter is the highest ever obtained for Au-nanostructures. Both nanostructures provide an enhancement that is high enough to detect single molecules using Raman scattering. The results are rationalized in terms of morphology effects on electromagnetic field intensity.

Journal article

S. Habouti
M. Mátéfi-Tempfli
C.-H. Solterbeck
M. Es-Souni
Stefan Mátéfi-Tempfli

On-substrate, self-standing Au-nanorods arrays showing morphology controlled properties.

In: Nano Today vol. 6 pg. 12-19

(2011)

DOI: 10.1016/j.nantod.2010.11.001

show abstract

We use supported alumina templates and electrodeposition to fabricate self-standing Au-nanorods (Au-NR) arrays. Depending on electrolyte and deposition conditions two different NR morphologies with either corrugated or smooth topologies are fabricated. We show that the properties of the NR arrays, including amphiphilic and optical, very much depend on their morphology. Smooth NR arrays are hydrophobic while the corrugated ones are hydrophilic. Also the optical reflectance, though it shows plasmon resonances at very similar wave lengths, is much lower for the corrugated NR arrays. The activity of the NR arrays as substrates for molecular detection using Raman scattering, and Rhodamine 6G (R6G) as model dye, also strongly depends on their morphology. R6G concentrations down to 1 pM are detected on the corrugated arrays yielding an effective enhancement factor (EF) of approximately 1 × 109. In contrast an over-estimated (because of their hydrophobic character) EF of 6 × 106 is obtained for the smooth NR arrays.

Journal article

V.-A. Antohe
A. Radu
Stefan Mátéfi-Tempfli
L. Piraux

Circuit Modeling on Polyaniline Functionalized Nanowire-Templated Micro-Interdigital Capacitors for pH Sensing.

In: IEEE Transactions on Nanotechnology vol. 10 pg. 1314-1320

(2011)

show abstract

This study presents an improved alternative current (ac) circuit modeling of a highly sensitive capacitive pH-sensing element based on polyaniline (PANI) functionalized nanowire-templated micro-interdigited electrodes (NWs μIDEs). While electrical resonance measurements deal with a total equivalent capacity, comparative investigations show a good agreement with the fitting parameters of the corresponding model. A physical interpretation of the model is discussed to help in understanding the detection mechanism and a possible methodology to be used for further integration of the subsequent device is suggested.

Lecture

Stefan Mátéfi-Tempfli

Electrochemical template synthesis of nanostructures. Invited seminar.

In: Institute of Condensed Matter Physics - Nanostructured & Complex Matter

École Polytechnique Fédérale de Lausanne Lausanne, Schweiz

Februar 2011 (2011)

Lecture

Stefan Mátéfi-Tempfli

Nanomaterials synthesis and applications. Invited talk.

Institut Charles Gerhardt, Chimie Moléculaire et des Matériaux Montpellier, Frankreich

Februar 2011 (2011)

Lecture

Stefan Mátéfi-Tempfli

Combining electrochemical template synthesis with classical lithography methods of micro- and nanopatterning. Invited seminar.

In: Physical Chemistry Symposium of the Center of Interface Science

Carl von Ossietzky Universität Oldenburg Oldenburg

April 2011 (2011)

Lecture

Stefan Mátéfi-Tempfli

Nanostructured materials and applications. Invited talk.

In: Centre for NanoHealth, College of Medicine and School of Engineering, Swansea University

Swansea, Großbritannien

April 2011 (2011)

Lecture

A. Milosavljević
K. Schiessl
C. Lemell
K. Tökési
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
B. Marinković
J. Burgdörfer

Charging dynamics in electron transmission through Al2O3 capillaries.

In: 5th Conference on Elementary Processes in Atomic Systems (CEPAS 2011)

Belgrad, Serbien

21.-25.06.2011 (2011)

Lecture

A. Milosavljević
J. Jureta
G. Víkor
Z. Pešić
D. Šević
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
B. Marinković

Guiding of low-energy electrons by Al2O3 nanocapillaries..

In: XXVII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2011)

Belfast, Nordirland, Großbritannien

27.07.-02.08.2011 (2011)

Lecture

Stefan Mátéfi-Tempfli

Combining electrochemical template synthesis with classical lithography methods of micro and nano-patterning. Invited talk.

Nanoscience Centre NanoSYD, Mads Clausen Institute at University of Southern Denmark Sønderborg, Dänemark

August 2011 (2011)

Journal article

A. Milosavljević
K. Schiessl
C. Lemell
K. Tökési
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
B. Marinković
J. Burgdörfer

Charging dynamics in electron transmission through Al2O3 capillaries.

In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms vol. 279 pg. 190-193

(2012)

show abstract

We have measured the transmission of low-energy electrons through insulating Al2O3 nanocapillaries. We find that transmission at the incident energy is quickly suppressed with increasing tilt angle of the capillary axis relative to the incoming electron beam while inelastic transmission becomes more important. For small angles of incidence charging dynamics lead to a decrease of total transmission (elastic and inelastic) with time. Our results are interpreted on the basis of a microscopic model for the electron transport within the capillary including also close interactions with the capillary wall.

Lecture

Stefan Mátéfi-Tempfli

Harvesting energy from the environment :Toward cleaner, safer and more efficient approaches. Fellow lecture.

In: Hanse-Wissenschaftskolleg Institute for Advanced Study

Delmenhorst

March 2012 (2012)

Lecture

H. Bülter
G. Wittstock
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
G. Denuault

Scanning electrochemical microscopy: Investigation of oxygen evolution from nanostructured iron oxide films and nanowires.

In: 12th International Fischer Symposium "Frontiers in Nanoelectrochemistry"

Lübeck

03.-07.06.2012 (2012)

Lecture

H. Bülter
G. Wittstock
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
G. Denuault

Scanning electrochemical microscopy : Investigation of oxygen evolution from nanostructured iron oxide films and nanowires..

In: Electrochemistry 2012: Fundamental and Engineering Needs for Sustainable Development

München

17.-19.09.2012 (2012)

Lecture

H. Bülter
G. Wittstock
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
G. Denuault

Scanning electrochemical microscopy : Investigation of oxygen evolution from nanostructured iron oxide fims and nanowires.

In: 23rd Lecture Conference on Photochemistry

Potsdam

08.-10.10.2012 (2012)

Journal article

O. Dmytriiev
U.A.S. Al-Jarah
Gangmei P.
V. Kruglyak
R. Hicken
B. Mahato
B. Rana
M. Agrawal
A. Barman
M. Mátéfi-Tempfli
L. Piraux
Stefan Mátéfi-Tempfli

Static and dynamic magnetic properties of densely packed magnetic nanowire arrays.

In: Physical Review B vol. 87 pg. 1744429 (19)

(2013)

DOI: 10.1103/PhysRevB.87.174429

show abstract

The static and dynamic magnetic properties of magnetic nanowire arrays with high packing density (>0.4) and wire diameter much greater than the exchange length have been studied by static and time-resolved magneto-optical Kerr effect measurements and micromagnetic simulations. The nanowires were formed by electrodeposition within a nanoporous template such that their symmetry axes lay normal to the plane of the substrate. A quantitative and systematic investigation has been made of the static and dynamic properties of the array, which lie between the limiting cases of a single wire and a continuous ferromagnetic thin film. In particular, the competition between anisotropies associated with the shape of the individual nanowires and that of the array as a whole has been studied. Measured and simulated hysteresis loops are largely anhysteretic with zero remanence, and the micromagnetic configuration is such that the net magnetization vanishes in directions orthogonal to the applied field. Simulations of the remanent state reveal antiferromagnetic alignment of the magnetization in adjacent nanowires and the formation of vortex flux closure structures at the ends of each nanowire. The excitation spectra obtained from experiment and micromagnetic simulations are in qualitative agreement for magnetic fields applied both parallel and perpendicular to the axes of the nanowires. For the field parallel to the nanowire axes, there is also good quantitative agreement between experiment and simulation. The resonant frequencies are initially found to decrease as the applied field is increased from remanence. This is the result of a change of mode profile within the plane of the array from nonuniform to uniform as the ground state evolves with increasing applied field. Quantitative differences between experimental and simulated spectra are observed when the field is applied perpendicular to the nanowire axes. The dependence of the magnetic excitation spectra upon the array packing density is explored, and dispersion curves for spin waves propagating within the array parallel to the nanowire axis are presented. Finally, a tunneling of end modes through the middle region of the nanowires was observed. The tunneling is more efficient for wires forming densely packed arrays, as a result of the extended penetration of the dynamic demagnetizing fields into the middle of the wires and due to the lowering of the tunneling barrier by the static demagnetizing field of the array.

Lecture

A. Goszczak
M. Madsen
J. Hoyland
Stefan Mátéfi-Tempfli
H.-G. Rubahn

Nanostructures for organic solar cells.

In: NANOTEXNOLOGY 2013

Thessaloniki, Griechenland

06.-13.07.2013 (2013)

Lecture

Stefan Mátéfi-Tempfli

Nanostructured materials and interfaces for enhancing photoelectrical and photoelectrochemical conversion. Invited lecture.

In: Physics and Chemistry of Advanced Materials (PCAM) European network summer school

Lago di Como, Italien

September 2013 (2013)

Lecture

G. Wittstock
G. Denuault
Stefan Mátéfi-Tempfli
H. Bülter
M. Mátéfi-Tempfli
A. Lesch
I. Schmidt
C. Dosche
M. Ahlf
K. Al-Shamery
A. Fanget
L. Forró

Oxygen evolution at vertically aligned core-shell iron-iron oxide nanowire arrays.

In: 24th ECS Meeting: Photoelectrochemistry and Photoassisted Electrocatalysis

San Francisco, CA, USA

27.10.-01.11.2013 (2013)

Contribution

A. Drimus
V. Jankovics
M. Gorsic
Stefan Mátéfi-Tempfli

High Resolution Tactile Sensors for Curved Robotic Fingertips.

In: Biomimetic and Biohybrid Systems. Proceedings of the Third International Conference Living Machines 2014 ( July 30-August 1, 2014; Milan, Italy) (Lecture Notes in Computer Science) pg. 383-385

Eds.:
A. Duff

Springer Cham

(2014)

DOI: 10.1007/978-3-319-09435-9_37

show abstract

Tactile sensing is a key element for various animals that interact with the environment and surrounding objects. Touch provides information about contact forces, torques and pressure distribution and by the means of exploration it provides object properties such as geometry, stiffness and texture[5]. For humans, extracting high level information from touch provides a better understanding of the objects manipulated while for insects it is essential for locomotion[3]. While robot designers have been using vision systems to provide the robot with information about its surroundings, this is not always trivial to obtain, dealing with limited accuracy, occlusions and calibration problems. In terms of sensors for static stimuli, such as pressure, there are a range of technologies that can be used to manufacture transducers with various results[5]. A simple approach is to use fingertips with a 6-DOF force-torque sensor for estimating contact conditions[1], but this only allows a single point of contact and is costly. In terms of fingertip and foot tip prototypes, tactile sensors are used for multi modal sensing, similar to biology, for pressure and dynamic stimuli. In this respect Hosoda et al. [4] propose an anthropomorphic fingertip which has randomly distributed straingauges and PVDF (polyvinylidene fluoride) transducers. In [7] a biomimetic tactile array is proposed that shows a low hysteresis and good sensitivity for skin like deformations.

Contribution

L. Duggen
Stefan Mátéfi-Tempfli

Forces in Liquid Metal Contacts.

In: Proceedings of the ASME 12th Biennial Conference on Engineering Systems Design and Analysis--2014. Volume 3: Engineering Systems; Heat Transfer and Thermal Engineering; Materials and Tribology; Mechatronics; Robotics (July 25–27, 2014; Copenhagen, Denmark) pg. V003T15A004

American Society of Mechanical Engineers New York, N.Y.

(2014)

DOI: 10.1115/ESDA2014-20114

show abstract

Using rather well known theory about capillary bridges between two electrodes we calculate the tensile force that can be applied to liquid metal contacts in the micrometer regime. Assuming circular symmetry, full wetting of the electrodes, and neglecting gravity, we present a brief review of the necessary theory and find numerically the forces to be in the 100μN range for liquid metals as mercury and liquid Gallium suspended between electrodes of 20μm radius.

Journal article

A. Drimus
V. Jankovics
M. Gorsic
Stefan Mátéfi-Tempfli

Novel high resolution tactile robotic fingertips.

In: IEEE SENSORS pg. 791-794

(2014)

DOI: 10.1109/ICSENS.2014.6985118

show abstract

This paper describes a novel robotic fingertip based on piezoresistive rubber that can sense pressure tactile stimuli with a high spatial resolution over curved surfaces. The working principle is based on a three-layer sandwich structure (conductive electrodes on top and bottom and piezoresistive rubber in the middle). For the conductive layers we use ring patterns of silver epoxy and flex PCB electrode arrays. The proposed sensorised fingertip has 60 sensitive regions (taxels) arranged in 5 rings and 12 columns that have a smooth pressure to resistance characteristic. Using the sensor with specialized data acquisition electronics that acquire 500 frames per second provides rich information regarding contact force, shape and angle for bio-inspired robotic fingertips. Furthermore, a model of estimating the force of contact based on values of the cells is proposed.

Lecture

Stefan Mátéfi-Tempfli

Mechatronics. Track chair.

In: ASME 2014: 12th Biennial Conference on Engineering Systems Design and Analysis : Engineering Systems; Heat Transfer and Thermal Engineering; Materials and Tribology; Mechatronics; Robotics

American Society of Mechanical Engineers, Copenhagen Copenhagen, Denmark

June 2014 (2014)

Lecture

L. Duggen
Stefan Mátéfi-Tempfli

Forces in Liquid Metal Contacts.

In: ASME 12th Biennial Conference on Engineering Systems Design and Analysis - ESDA 2014

Kopenhagen, Dänemark

25.-27.07.2014 (2014)

Lecture

A. Drimus
V. Jankovics
M. Gorsic
Stefan Mátéfi-Tempfli

High Resolution Tactile Sensors for Curved Robotic Fingertips.

In: 3rd International Conference on "Living Machines"

Mailand, Italien

30.07.-01.08.2014 (2014)

Contribution

A. Drimus
Stefan Mátéfi-Tempfli

Tactile shoe inlays for high speed pressure monitoring.

In: Intelligent Robotics and Applications. Proceedings of the 8th International Conference (ICIRA 2015) [August 24-27, 2015; Portsmouth, UK] (Lecture Notes in Computer Science) pg. 74-81

Eds.:
L. Honghai

Springer Berlin

(2015)

Contribution

P. Farhang
A. Drimus
Stefan Mátéfi-Tempfli

New technique for voltage tracking control of a boost converter based on the PSO algorithm and LTspice.

In: 2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON). pg. 1-6

(2015)

DOI: 10.1109/RTUCON.2015.7343157

Lecture

Oliveira Hansen, R. M. D.
M. Mátéfi-Tempfli
S. Chemnitz
T. Reimer
B. Wagner
Stefan Mátéfi-Tempfli
W. Benecke
H.-G. Rubahn

Electromagnetic actuation in MEMS switches.

In: 100% CLIMATE NEUTRALITY Conference

Sønderborg, Denmark

6.-7.10.2015 (2015)

Lecture

A. Drimus
V. Jankovics
M. Gorsic
Stefan Mátéfi-Tempfli

Novel high resolution tactile robotic fingertips.

In: IEEE SENSORS 2014

Valencia, Spanien

02.-05.11.2015 (2015)

Lecture

R. Brehm
S. Top
Stefan Mátéfi-Tempfli

A distributed multi-agent linear bi-objective algorithm for energy flow optimization in microgrids.

In: 3rd International Renewable and Sustainable Energy Conference (IRSEC'15)

Marrakech-Ouarzazate, Morocco

10-13.12.2015 (2015)

Contribution

P. Farhang
Stefan Mátéfi-Tempfli

A New Approach to Control the Modified LinVerter for High Frequency Applications.

In: Proceedings of the 31st Annual IEEE Applied Power Electronics Conference and Exposition (APEC2016) [March 20-24, 2016; Long Beach, USA]. pg. 733-738

IEEE Press

(2016)

Contribution

V. Jankovics
Stefan Mátéfi-Tempfli
P. Manoonpong

Artifcial neural network based complaint control for robot arms.

In: From Animals to Animats 14. Proceedings of the 14th International Conference on Simulation of Adaptive Behavior (SAB 2016) [August 23-26, 2016; Aberystwyth, UK] (Lecture Notes in Computer Science) pg. 91-100

Eds.:
Myra Wilson
A. Giagkos
Elio Tuci
J. Hallam

Springer, Cham

(2016)

Contribution

R. Brehm
S. Top
Stefan Mátéfi-Tempfli

A distributed multi-agent linear bi-objective algorithm for energy flow optimization in microgrids.

In: Proceedings of 2015 IEEE International Renewable and Sustainable Energy Conference (IRSEC'15). pg. 804-809

Eds.:
M. Essaaidi
Y. Zaz

IEEE Press

(2016)

Journal article

H. Bülter
G. Denuault
Stefan Mátéfi-Tempfli
M. Mátéfi-Tempfli
C. Dosche
G. Wittstock

Electrochemical analysis of nanostructured iron oxides using cyclic voltammetry and scanning electrochemical microscopy.

In: Electrochimica Acta vol. 222 pg. 1326-1334

(2016)

show abstract

Iron oxides in general and especially hematite, α-Fe2O3, have become promising materials for the alkaline water electrolysis and photoelectrochemical water splitting, respectively. In the present study electrocatalytic electrodes with a thin film of α-Fe2O3 and with vertically aligned α-Fe2O3 nanowires were prepared. Cyclic voltammograms of the α-Fe2O3 nanowires revealed differences including a series of three unreported cathodic signals when compared to previously published voltammograms for polycrystalline iron oxides. The generation-collection mode of scanning electrochemical microscopy (SECM) using nanostructured Pt microdisc probes was exploited to detect soluble reaction products formed at the voltammetric peaks of the α-Fe2O3 electrode. SECM tip-substrate voltammetry unexpectedly showed that the reduction of FeVI to FeIII on the cathodic sweep is accompanied by significant O2 evolution.

Lecture

P. Farhang
Stefan Mátéfi-Tempfli

A New Approach to Control the Modified LinVerter for High Frequency Applications.

In: IEEE Applied Power Electronics Conference (APEC2106)

Long Beach (Los Angeles), CA, USA

20-24.03.2016 (2016)

Lecture

P. Farhang
A. Drimus
Stefan Mátéfi-Tempfli

New Technique for Voltage Tracking Control of a Boost Converter Based on the PSO Algorithm and LTspice.

In: 57th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)

Riga, Lettland

13.-14.10.2016 (2016)

Journal article

J. Branch
M. Alibouri
D. Cook
P. Richardson
P. Bartlett
M. Mátéfi-Tempfli
Stefan Mátéfi-Tempfli
M. Bampton
T. Cookson
P. Connell
D. Smith

Plastic Reactor Suitable for High Pressure and Supercritical Fluid Electrochemistry.

In: Journal of The Electrochemical Society vol. 164 pg. H375-H381

(2017)

show abstract

The paper describes a reactor suitable for high pressure, particularly supercritical fluid, electrochemistry and electrodeposition at pressures up to 30 MPa at 115°C. The reactor incorporates two key, new design concepts; a plastic reactor vessel and the use of o-ring sealed brittle electrodes. These two innovations widen what can be achieved with supercritical fluid electrodeposition. The suitability of the reactor for electroanalytical experiments is demonstrated by studies of the voltammetry of decamethylferrocene in supercritical difluromethane and for electrodeposition is demonstrated by the deposition of Bi. The application of the reactor to the production of nanostructures is demonstrated by the electrodeposition of ∼80 nm diameter Te nanowires into an anodic alumina on silicon template. Key advantages of the new reactor design include reduction of the number of wetted materials, particularly glues used for insulating electrodes, compatability with reagents incompatible with steel, compatability with microfabricated planar multiple electrodes, small volume which brings safety advantages and reduced reagent useage, and a significant reduction in experimental time.

Journal article

P. Coman
Stefan Mátéfi-Tempfli
S. Veje
R. White

Modeling Vaporization, Gas Generation and Venting in Li-Ion Battery Cells with a Dimethyl Carbonate Electrolyte.

In: Electrochemical Society Journal vol. 164 pg. A1858-A1865

(2017)

show abstract

This paper presents a mathematical model developed for predicting the temperature-pressure behavior and gas generation inside 18650 LCO/Graphite cells with a DMC (Dimethyl Carbonate) electrolyte. The cell was modeled using oven heating conditions, and the analysis was done at time intervals around the venting event. The paper also presents the thermodynamic property table for DMC, as extracted from different resources and calculated using various assumptions. The model was developed by deriving the energy balance for an unsteady-flow control volume and applying the isentropic flow equations corresponding to the venting of gas. The results show that the model fails to predict the pressure measured experimentally when no gas is generated inside. When adding the gas generation due to pre-venting reactions occurring, the model can predict the pressure profile measured experimentally.

Lecture

A. Milosavljević
G. Víkor
Z. Pešić
Stefan Mátéfi-Tempfli
et al.

Guiding of Electrons by Al2O3 Nanocapillaries.

In: Symposium on Condensed Matter Physics (SFKM)

Vrsaca, Serbien

16.-20.09.2017 (2017)

Journal article

de Oliveira Hansen, R. M. D.
M. Mátéfi-Tempfli
R. Safonovs
J. Adam
S. Chemnitz
T. Reimer
B. Wagner
W. Benecke
Stefan Mátéfi-Tempfli

Magnetic films for electromagnetic actuation in MEMS switches.

In: Microsystem Technologies vol. 24 pg. 1987-1994

(2018)

DOI: 10.1007/s00542-017-3595-2

show abstract

This paper investigates the fabrication of magnetic films via electroplating to be applied into electromagnetic actuated micro electro-mechanical systems (MEMS) switches. Cobalt and nickel films (1 µm thicknesses) were deposited on gold coated silicon substrates via electrochemical deposition. Different deposition conditions were investigated, regarding temperature and deposition voltage. The films morphologies were characterized via atomic force microscopy, while the magnetic properties of the films were characterized via vibrating sample magnetometer measurements. In order to evaluate the integration of these magnetic films into MEMS switches with low energy consumption, a mathematical model was developed and the results show that these films can be applied into efficient actuation with reduced power dissipation.

Contribution

V. Dürr
P. Arena
H. Cruse
Ch.J. Dallmann
A. Drimus
T. Hoinville
T. Krause
Stefan Mátéfi-Tempfli
J. Paskarbeit
L. Patane
M. Schilling
J. Schmitz
R. Strauss
A. Vitanza
A. Schneider

Integrative Biomimetics of Autonomous Hexapedal Locomotion.

In: Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) [November 3-8, 2019; Macau, China]. pg. 1-32

(2019)

show abstract

Despite substantial advances in many different fields of neurorobotics in general, and biomimetic robots in particular, a key challenge is the integration of concepts: to collate and combine research on disparate and conceptually disjunct research areas in the neurosciences and engineering sciences. We claim that the development of suitable robotic integration platforms is of particular relevance to make such integration of concepts work in practice. Here, we provide an example for a hexapod robotic integration platform for autonomous locomotion. In a sequence of six focus sections dealing with aspects of intelligent, embodied motor control in insects and multipedal robots—ranging from compliant actuation, distributed proprioception and control of multiple legs, the formation of internal representations to the use of an internal body model—we introduce the walking robot HECTOR as a research platform for integrative biomimetics of hexapedal locomotion. Owing to its 18 highly sensorized, compliant actuators, light-weight exoskeleton, distributed and expandable hardware architecture, and an appropriate dynamic simulation framework, HECTOR offers many opportunities to integrate research effort across biomimetics research on actuation, sensory-motor feedback, inter-leg coordination, and cognitive abilities such as motion planning and learning of its own body size.