Christoph Strunk

Reversal of Nonlocal Vortex Motion in the Regime of Strong Nonequilibrium (2009)

Otto, Florian, Bilusic, Ante, Babic, Dinko, Vodolazov, Denis Yu., Suergers, Christoph, Strunk, Christoph

We investigate nonlocal vortex motion in weakly pinning a-NbGe nanostructures, which is driven by a transport current I and remotely detected as a nonlocal voltage Vnl. At high I, the measured Vnl...

Doppler shift in Andreev reflection from a moving superconducting condensate in Nb/InAs Josephson junctions (2009)

Rohlfing, Franziska, Tkachov, Grygoriy, Otto, Florian, Richter, Klaus, Weiss, Dieter, Borghs, G, ...

We study narrow ballistic Josephson weak links in an InAs quantum well contacted by Nb electrodes. Measurements of the conductance, excess and critical currents reveal a dramatic magnetic-field...

Effect of Microwaves on the Current-Phase Relation of Superconductor-Normal-Metal-Superconductor Josephson Junctions (2009)

Fuechsle, M., Bentner, J., Ryndyk, D.A., Reinwald, Matthias, Wegscheider, Werner, Strunk, Christoph

We investigate the current-phase relation (CPR) of long diffusive superconductor–normal-metal–superconductor (Nb/Ag/Nb) Josephson junctions in thermodynamic equilibrium and under microwave...

Carbon nanotube Josephson junctions with Nb contacts (2008)

Pallecchi, Emiliano, Gaaß, Markus, Ryndyk, Dmitry, Strunk, Christoph

We report on the preparation of carbon nanotube Josephson junctions using superconducting electrodes made of niobium. Gate-controllable supercurrents with values of up to 30 nA are induced by the...

Edge-channel interference controlled by Landau level filling (2008)

Litvin, Leonid, Helzel, Andreas, Wegscheider, Werner, Strunk, Christoph

We study the visibility of Aharonov-Bohm interference in an electronic Mach-Zehnder interferometer in the integer quantum Hall regime. The visibility is controlled by the filling factor nu and is...

Effect of vortex-core size on the flux lattice in a mesoscopic superconducting strip (2008)

Kokanovic, I., Helzel, Andreas, Babic, D., Sürgers, C., Strunk, Christoph

We present an experimental study of the vortex-motion dissipation in a mesoscopic amorphous (a-)Nb0.7Ge0.3 strip, with emphasis on the results for 3-8 vortex rows parallel to the long strip axis. In...

Superinsulator and quantum synchronization (2008)

Vinokur, Valerii M., Baturina, Tatyana I., Fistul, Mikhail V., Mironov, Aleksey Yu., Baklanov, Mikhail R., Strunk, Christoph

Synchronized oscillators are ubiquitous in nature1, and synchronization plays a key part in various classical and quantum phenomena. Several experiments2, 3, 4 have shown that in thin superconducting...

Carbon Nanotube Quantum Dots with Nb Contacts (2008)

Pallecchi, Emiliano, Gaass, Markus, Ryndyk, Dmitry, Strunk, Christoph

We report on the preparation of carbon nanotube quantum dots using superconducting electrodes made of niobium. Gate-controllable supercurrents with values of up to 30 nA are induced by the proximity...

Bistability in superconducting rings containing an inhomogeneous Josephson junction (2008)

Gaaß, Markus, Nadj-Perge, S., Radovic, Z., Bauer, A, Aprili, M, Wegscheider, Werner, ...

We investigate the magnetic response of a superconducting Nb ring containing a ferromagnetic PdNi Josephson junction and a tunnel junction in parallel. Doubling of the switching frequency is observed...

1/f flux flow noise due to a coexistence of qualitatively different vortex states (2007)

Babic, D., Bentner, J., Sürgers, C., Strunk, Christoph

We investigate the vortex-motion voltage noise in a hybrid structure consisting of a weak-pinning amorphous Nb0.7Ge0.3 microbridge on top of which a strong-pinning, longitudinal Nb line with a narrow...

Half-integer flux quantization in a superconducting loop with a ferromagnetic pi-junction (2007)

Bauer, A., Bentner, J., Aprili, M., Della Rocca, L, Strunk, Christoph

Superconducting loops containing a pi-junction are predicted to show a spontaneous magnetic moment in zero external magnetic field. In order to confirm this longstanding prediction experimentally, we...

Decoherence and single electron charging in an electronic Mach-Zehnder interferometer (2007)

Tranitz, H., Wegscheider, Werner, Strunk, Christoph

We investigate the temperature and voltage dependence of the quantum interference in an electronic Mach-Zehnder interferometer using edge channels in the integer quantum-Hall regime. The amplitude of...

Competition between magnetic field dependent band structure and coherent backscattering in multiwall carbon nanotubes (2007)

Stojetz, B., Roche, S., Miko, C., Triozon, F., Forró, L., Strunk, Christoph

Abstract. Magnetotransport measurements in large diameter multiwall carbon nanotubes (20–40 nm) demonstrate the competition of a magnetic-field dependent bandstructure and Altshuler–Aronov–Spivak...

Quantum metallicity at the High-Field Side of the Superconductor-Insulator Transition (2007)

Baturina, T., Strunk, Christoph, Satta, A.

We investigate ultrathin superconducting TiN films, which are very close to the localization threshold. Perpendicular magnetic field drives the films from the superconducting to an insulating state,...

Localized Superconductivity in the Quantum-Critical Region around the Disorder-Driven Superconductor-Insulator Transition (2007)

Baturina, T., Mironov, A., Vinokur, V., Baklanov, M., Strunk, Christoph

We investigate low-temperature transport properties of thin TiN superconducting films, which differ in the degree of disorder. In zero magnetic field, we find an extremely sharp separation between...

Aharonov-Bohm effects in multiwall carbon nanotubes (2006)

Strunk, Christoph, Stojetz, Bernhard

We investigate quantum transport phenomena in multiwall carbon nanotubes in perpendicular and parallel magnetic field. An efficient gating technique allows for a considerable tuning of the nanotube...

Quantum interference in multiwall carbon nanotubes (2006)

Strunk, Christoph, Stojetz, B., Roche, S.

Abstract. Recent low temperature conductance measurements on multiwall carbon nanotubes in perpendicular and parallel magnetic fields are reported. An efficient gating technique allows for...

Nonlocal vortex motion in mesoscopic amorphous Nb0.7Ge0.3 structures (2006)

Helzel, Andreas, Kokanovic, I., Babic, D., Litvin, Leonid, Rohlfing, Franziska, Otto, Florian, ...

We study nonlocal vortex transport in mesoscopic amorphous Nb0.7Ge0.3 samples. A dc current I is passed through a wire connected via a perpendicular channel, of a length L=2–5 µm, with a pair of...

Effect of Band Structure on Quantum Interference in Multiwall Carbon Nanotubes (2005)

Stojetz, Bernhard, Miko, Csilla, Forro, Laszlo, Strunk, Christoph

We report conductance measurements on multiwall carbon nanotubes in a perpendicular magnetic field. A gate electrode with large capacitance is used to considerably vary the nanotube Fermi level. This...

Quantum Transport in Carbon Nanotubes (2005)

Thune, E., Strunk, Christoph

Abstract We present a tutorial introduction into the structure and electronic properties of carbon nanotubes which may serve as an entry point into the literature on the field. Some of the original...

Quantenwelt im Nanozylinder: Elektronische Eigenschaften von Kohlenstoff-Nanoröhrchen (2005)

Strunk, Christoph

Abstract Kohlenstoff-Nanoröhren sind einzelne oder mehrfach ineinander gesteckte molekulare Hohlzylinder. In ihnen bilden Kohlenstoffatome ein Graphit ähnliches Kristallgitter. Diese Fullerene...

Bandstructure Effects in Multiwall Carbon Nanotubes (2004)

Stojetz, Bernhard, Miko, Csilla, Forro, Laszlo, Strunk, Christoph

We report conductance measurements on multiwall carbon nanotubes in a perpendicular magnetic field. A gate electrode with large capacitance is used to considerably vary the nanotube Fermi level. This...

Spontaneous Supercurrent Induced by Ferromagnetic π Junctions (2004)

Bauer, A, Bentner, J, Aprili, M, Della Rocca, L, Reinwald, Matthias, Wegscheider, Werner, ...

We present magnetization measurements of mesoscopic superconducting niobium loops containing a ferromagnetic (PdNi) π junction. The loops are prepared on top of the active area of a micro-Hall...

Flux-flow instabilities in amorphous Nb0.7Ge0.3 microbridges (2004)

Babić, D., Bentner, J., Sürgers, C., Strunk, Christoph

We report measurements of the electric field vs current density [E(J)] characteristics in the mixed state of amorphous Nb0.7Ge0.3 microbridges. Close to the transition temperature Tc the...

Ensemble averaging of conductance fluctuations in multiwall carbon nanotubes (2004)

Stojetz, B., Hagen, Christian, Hendlmeier, Christof, Ljubovic, E., Forró, L., Strunk, Christoph

Abstract. We report resistance measurements for a single multiwall carbon nanotube as a function of gate voltage and perpendicular magnetic field. The tubes were trapped onto pre-patterned Al...

Superconductivity on the localization threshold and magnetic-field-tuned superconductor-insulator transition in TiN films (2004)

Baturina, T., Islamov, D., Bentner, J., Strunk, Christoph, Baklanov, M., Satta, A.

Abstract Temperature-and magnetic-field-dependent measurements of the resistance of ultrathin superconducting TiN films are presented. The analysis of the temperature dependence of the zero-field...

Boosting Magnetoresistance in Molecular Devices (2004)

Strunk, Christoph

Magnetoelectronics and molecular electronics are two emerging branches of nanoelectronics, which are believed to have large potential for future device applications. In his perspective, Strunk...

Shot noise of series quantum point contacts intercalating chaotic cavities (2002)

Oberholzer, Stefan, Sukhorukov, Eugene V., Strunk, Christoph, Schonenberger, Christian

Shot noise of series quantum point contacts forming a sequence of cavities in a two-dimensional electron gas are studied theoretically and experimentally. Noise in such a structure originates from...

The amplitude of non-equilibrium quantum interference in metallic mesoscopic systems (2002)

Terrier, C, Babic, D., Strunk, Christoph, Nussbaumer, Thomas

We study the influence of a DC bias voltage V on quantum interference corrections to the measured differential conductance in metallic mesoscopic wires and rings. The amplitude of both universal...

Vortex motion noise in micrometer-sized thin films of the amorphous Nb0.7Ge0.3 weak-pinning superconductor (2002)

Babic, Dragutin, Nussbaumer, Thomas, Strunk, Christoph, Schonenberger, Christian, Sürgers, Christoph

The modeling and control of a three-phase threes-witch buck-type rectifier system with integrated boost output stage (Voltage Range Extended 4-Switch Rectifier) is analyzed in this paper. A cascaded...

UHV compatible nanostructuring technique for mesoscopic hybrid devices: application to superconductor/ferromagnet Josephson contacts (2002)

Hoss, T, Strunk, Christoph, Sürgers, C., Schönenberger, Christian

We report on an ultra-high vacuum (UHV) compatible method for fabricating devices of sub-micrometer size by virtue of a non-organic evaporation mask of high thermal and mechanical stability. As an...

Fabrication and superconducting properties of nanostructured SFS contacts (2002)

Sürgers, Christoph, Hoss, Tilman, Schonenberger, Christian, Strunk, Christoph

Superconducting hybrid structures of submicrometer size utilizing high-melting transition metals such as Nb or Ta can be fabricated in ultra-high vacuum by means of a non-organic evaporation mask...

Shot noise by quantum scattering in chaotic cavities (2001)

Oberholzer, Stefan, Sukhorukov, Eugene V., Strunk, Christoph, Schonenberger, Christian, Heinzel, T., Holland, M.

We have experimentally studied shot noise of chaotic cavities defined by two quantum point contacts in series. The cavity noise is determined as (1/4)2e[1] in agreement with theory and can be well...

Universal conductance fluctuations and low-temperature 1/f noise in mesoscopic AuFe spin glasses (2000)

Neuttiens, G., Strunk, Christoph, Van Haesendonck, C., Bruynseraede, Y.

We report on intrinsic time-dependent conductance fluctuations observed in mesoscopic AuFe spin-glass wires. These dynamical fluctuations have a 1/f-like spectrum and appear below the measured...

Multiple Andreev reflection and giant excess noise in diffusive superconductor/normal-metal/superconductor junctions (2000)

Hoss, Tilman, Strunk, Christoph, Nussbaumer, Thomas, Huber, R., Staufer, U., Schonenberger, Christian

We have studied superconductor/normal-metal/superconductor (SNS) junctions consisting of shea Au or Cu wires between Nh or Al banks. The Nb based junctions display inherent electron heating effects...

The Hanbury Brown and Twiss experiment with fermions (2000)

Oberholzer, Stefan, Henny, M., Strunk, Christoph, Schonenberger, Christian, Heinzel, Thomas, Ensslin, Klaus, ...

We realized an equivalent Hanbury Brown and Twiss experiment for a beam of electrons in a two-dimensional electron gas in the quantum Hall regime. A metallic split gate serves as a tunable beam...

The Fermionic Hanbury Brown and Twiss Experiment (1999)

Henny, M., Oberholzer, Stefan, Strunk, Christoph, Heinzel, T., Ennslin, K., Holland, M.

A Hanbury Brown and Twiss experiment for a beam of electrons has been realized in a two-dimensional electron gas in the quantum Hall regime. A metallic split gate serves as a tunable beam splitter to...

Aharonov-Bohm oscillations in carbon nanotubes (1999)

Bachtold, Adrian, Strunk, Christoph, Salvetat, Jean-Paul, Bonard, Jean-Marc, Forro, Laszlo, Nussbaumer, Thomas, ...

When electrons pass through a cylindrical electrical conductor aligned in a magnetic field, their wave-like nature manifests itself as a periodic oscillation in the electrical resistance as a...

Size Dependent Thermopower in Mesoscopic AuFe Wires (1998)

Strunk, Christoph, Henny, M., Schönenberger, Christian, Neuttiens, G., Van Haesendonck, C.

We have combined electron heating experiments and noise thermometry to perform quantitative measurements of the thermopower in mesoscopic samples. This new measuring technique allows us to detect...