Nonlinear magneto-gyrotropic photogalvanic effect (2009)
Diehl, Helgi, Shalygin, Vadim, Golub, Leonid, Tarasenko, Sergey, Danilov, Sergey, Belkov, Vassilij, ...
We report on the observation of magnetic-field-induced photocurrent in HgTe/HgCdTe quantum wells of different widths. Both the intrasubband and interband absorption of infrared/terahertz radiation in...
Tunneling anisotropic magnetoresistance in organic spin valves (2009)
Gruenewald, M., Wahler, M., Michelfeit, M., Gould, C., Schmidt, R., Graziosi, P., ...
We report the observation of tunneling anisotropic magnetoresistance (TAMR) in an organic spin valve with only one ferromagnetic electrode. The spin valve is based on a new high mobility perylene...
Lateral magnetic anisotropy superlattice out of a single (Ga,Mn)As layer (2009)
Dengel, R. G., Gould, C., Wenisch, J., Brunner, K., Schmidt, G., Molenkamp, L. W.
We use lithographically induced strain relaxation to periodically modulate the magnetic anisotropy in a single (Ga,Mn)As layer. This results in a lateral magnetoresistance device where two...
Fermi-edge Singularity in II-VI Semiconductor Resonant Tunneling Structures (2009)
Rueth, M., Slobodskyy, T., Gould, C., Schmidt, G., Molenkamp, L. W.
We report on the observation of Fermi edge enhanced resonant tunneling transport in a II-VI semiconductor heterostructure. The resonant transport through a self assembled CdSe quantum dot survives up...
Bistability of vortex core dynamics in a single perpendicularly magnetized nano-disk (2009)
De Loubens, Grégoire, Riegler, A., Pigeau, B., Lochner, F., Boust, F., Guslienko, K.Y., ...
Microwave spectroscopy of individual vortex-state magnetic nano-disks in a perpendicular bias magnetic field, $H$, is performed using a magnetic resonance force microscope (MRFM). It reveals the...
Bistability of vortex core dynamics in a single perpendicularly magnetized nano-disk (2009)
De Loubens, Grégoire, Riegler, A., Pigeau, B., Lochner, F., Boust, F., Guslienko, K.Y., ...
Microwave spectroscopy of individual vortex-state magnetic nano-disks in a perpendicular bias magnetic field, $H$, is performed using a magnetic resonance force microscope (MRFM). It reveals the...
Ballistic Intrinsic Spin-Hall Effect in HgTe Nanostructures (2008)
Bruene, C., Roth, A., Novik, E. G., Koenig, M., Buhmann, H., Hankiewicz, E. M., ...
We report the first electrical manipulation and detection of the mesoscopic intrinsic spin-Hall effect (ISHE) in semiconductors through non-local electrical measurement in nano-scale H-shaped...
Independent magnetization behavior of a ferromagnetic metal/semiconductor hybrid system (2008)
Mark, S., Gould, C., Pappert, K., Wenisch, J., Brunner, K., Schmidt, G., ...
We report the discovery of an effect where two ferromagnetic materials, one semiconductor ((Ga,Mn)As) and one metal (permalloy), can be directly deposited on each other and still switch their...
Time-resolved and continuous-wave optical spin pumping of semiconductor quantum wells (2008)
Astakhov, G. V., Glazov, M. M., Yakovlev, D. R., Zhukov, E. A., Ossau, W., Molenkamp, L. W., ...
Experimental and theoretical studies of all-optical spin pump and probe of resident electrons in CdTe/(Cd,Mg)Te semiconductor quantum wells are reported. A two-color Hanle-MOKE technique (based on...
Detailed transport investigation of the magnetic anisotropy of (Ga,Mn)As (2008)
Pappert, K., Gould, C., Sawicki, M., Wenisch, J., Brunner, K., Schmidt, G., ...
This paper discusses transport methods for the investigation of the (Ga,Mn)As magnetic anisotropy. Typical magnetoresistance behaviour for different anisotropy types is discussed, focusing on an in...
An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material (2008)
Gould, C., Mark, S., Pappert, K., Dengel, G., Wenisch, J., Campion, R. P., ...
This paper reports on a detailed magnetotransport investigation of the magnetic anisotropies of (Ga,Mn)As layers produced by various sources worldwide. Using anisotropy fingerprints to identify...
Bistability of vortex core dynamics in a single perpendicularly magnetized nano-disk (2008)
De Loubens, Grégoire, Riegler, A., Pigeau, B., Lochner, F., Boust, F., Guslienko, K.Y., ...
Microwave spectroscopy of individual vortex-state magnetic nano-disks in a perpendicular bias magnetic field, $H$, is performed using a magnetic resonance force microscope (MRFM). It reveals the...
Resonant tunneling diode with spin polarized injector (2007)
Slobodskyy, A., Gould, C., Slobodskyy, T., Schmidt, G., Molenkamp, L. W., Sanchez, D.
We investigate the current-voltage characteristics of a II-VI semiconductor resonant-tunneling diode coupled to a diluted magnetic semiconductor injector. As a result of an external magnetic field, a...
Quantum dot as thermal rectifier (2007)
Scheibner, R., Koenig, M., Reuter, D., Wieck, A. D., Buhmann, H., Molenkamp, L. W.
We report the observation of thermal rectification in a semiconductor quantum dot, as inferred from the asymmetric line shape of the thermopower oscillations. The asymmetry is observed at high...
Aharonov-Casher effect in a two dimensional hole gas with spin-orbit interaction (2007)
Kovalev, Alexey A., Borunda, Mario F., Jungwirth, T., Molenkamp, L. W., Sinova, Jairo
We study the quantum interference effects induced by the Aharonov-Casher phase in a ring structure in a two-dimensional heavy hole (HH) system with spin-orbit interaction realizable in narrow...
Exploiting Locally Imposed Anisotropies in (Ga,Mn)As: a Non-volatile Memory Device (2007)
Pappert, K., Hümpfner, S., Gould, C., Wenisch, J., Brunner, K., Schmidt, G., ...
Progress in (Ga,Mn)As lithography has recently allowed us to realize structures where unique magnetic anisotropy properties can be imposed locally in various regions of a given device. We make use of...
Control of magnetic anisotropy in (Ga,Mn)As by lithography-induced strain relaxation (2007)
Wenisch, J., Gould, C., Ebel, L., Storz, J., Pappert, K., Schmidt, M. J., ...
We obtain control of magnetic anisotropy in epitaxial (Ga,Mn)As by anisotropic strain relaxation in patterned structures. The strain in the structures is characterized using sophisticated X-ray...
Lithographic engineering of anisotropies in (Ga,Mn)As (2006)
Hümpfner, S., Sawicki, M., Pappert, K., Wenisch, J., Brunner, K., Gould, C., ...
The focus of studies on ferromagnetic semiconductors is moving from material issues to device functionalities based on novel phenomena often associated with the anisotropy properties of these...
Transport Characterization of the Magnetic Anisotropy of (Ga,Mn)As (2006)
Pappert, K., Hümpfner, S., Wenisch, J., Brunner, K., Gould, C., Schmidt, G., ...
The rich magnetic anisotropy of compressively strained (Ga,Mn)As has attracted great interest recently. Here we discuss a sensitive method to visualize and quantify the individual components of the...
Scheibner, R., Novik, E. G., Borzenko, T., Koenig, M., Reuter, D., Wieck, A. D., ...
We have studied the temperature dependent thermopower of gate-defined, lateral quantum dots in the Coulomb blockade regime using an electron heating technique. The line shape of the thermopower...
Current Assisted Magnetization Switching in (Ga,Mn)As Nanodevices (2006)
Gould, C., Pappert, K., Rüster, C., Giraud*, R., Borzenko, T., Schott, G. M., ...
Current induced magnetization switching and resistance associated with domain walls pinned in nanoconstrictions have both been previously reported in (Ga,Mn)As based devices, but using very...
Thermo-Electric Properties of Quantum Point Contacts (2005)
Van Houten, H., Molenkamp, L. W., Beenakker, C. W. J., Foxon, C. T.
I. Introduction II. Theoretical background (Landauer-Buttiker formalism of thermo-electricity, Quantum point contacts as ideal electron waveguides, Saddle-shaped potential) III. Experiments...
Tunneling magnetoresistance in devices based on epitaxial NiMnSb with uniaxial anisotropy (2005)
Liu, J., Girgis, E., Bach, P., Ruester, C., Gould, C., Schmidt, G., ...
We demonstrate tunnel magnetoresistance (TMR) junctions based on a tri layer system consisting of an epitaxial NiMnSb, aluminum oxide and CoFe tri layer. The junctions show a tunnelling...
Direct observation of the Aharonov-Casher phase (2005)
Koenig, M., Tschetschetkin, A., Hankiewicz, E. M., Sinova, Jairo, Hock, V., Daumer, V., ...
Ring structures fabricated from HgTe/HgCdTe quantum wells have been used to study Aharonov-Bohm type conductance oscillations as a function of Rashba spin-orbit splitting strength. We observe...
Kimel, A. V., Kirilyuk, A., Grabs, P., Lehmann, F., Tsvetkov, A. A., Schmidt, G., ...
Using an ultra sensitive magneto-optical Kerr rotation setup we have observed electrical spin injection from (Zn,Mn)Se into bulk GaAs and quantified the spin injection efficiency. The current induced...
Self Assembled II-VI Magnetic Quantum Dot as a Voltage-Controlled Spin-Filter (2005)
Gould, C., Slobodskyy, A., Slobodskyy, T., Grabs, P., Supp, D., Hawrylak, P., ...
A key element in the emergence of a full spintronics technology is the development of voltage controlled spin filters to selectively inject carriers of desired spin into semiconductors. We previously...
Thermopower of a Kondo-correlated quantum dot (2004)
Scheibner, R., Buhmann, H., Reuter, D., Kiselev, M. N., Molenkamp, L. W.
The thermopower of a Kondo-correlated gate-defined quantum dot is studied using a current heating technique. In the presence of spin correlations the thermopower shows a clear deviation from the...
Band structure of semimagnetic Hg1-yMnyTe quantum wells (2004)
Novik, E. G., Pfeuffer-Jeschke, A., Jungwirth, T., Latussek, V., Becker, C. R., Landwehr, G., ...
The band structure of semimagnetic Hg_1-yMn_yTe/Hg_1-xCd_xTe type-III quantum wells has been calculated using eight-band kp model in an envelope function approach. Details of the band structure...
Manifestation of the spin-Hall effect through transport measurements in the mesoscopic regime (2004)
Hankiewicz, E. M., Molenkamp, L. W., Jungwirth, T., Sinova, Jairo
We study theoretically the manifestation of the spin-Hall effect in a two-dimensional electronic system with Rashba spin-orbit coupling via dc-transport measurements in realistic mesoscopic H-shape...
1500-fold Tunneling Anisotropic Magnetoresistance in a (Ga,Mn)As stack (2004)
Rüster, C., Gould, C., Jungwirth, T., Sinova, J., Schott, G. M., Giraud, R., ...
We report the discovery of a super-giant tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The effect arises from a strong dependence of the...
Gould, C., Rüster, C., Jungwirth, T., Girgis, E., Schott, G. M., Giraud, R., ...
We introduce a new class of spintronics devices in which a spin-valve like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a...
Giant spin-orbit splitting in a HgTe quantum well (2004)
Gui, Y. S., Becker, C. R., Dai, N., Liu, J., Qiu, Z. J., Novik, E. G., ...
We have investigated beating patterns in Shubnikov-de Haas oscillations for HgTe/Hg_{0.3}Cd_{0.7}Te(001) quantum wells with electron densities of 2 to 3 X 10^{12} cm^{-2}. Up to 12 beating nodes have...
Low-field diffusion magneto-thermopower of a high mobility two-dimensional electron gas (2004)
Maximov, S., Gbordzoe, M., Buhmann, H., Molenkamp, L. W., Reuter, D.
The low magnetic field diffusion thermopower of a high mobility GaAs-heterostructure has been measured directly on an electrostatically defined micron-scale Hall-bar structure at low temperature (T =...
Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)As wires with nanoconstrictions (2003)
Ruester, C., Borzenko, T., Gould, C., Schmidt, G., Molenkamp, L. W., Liu, X., ...
We have fabricated (Ga,Mn)As nanostructures in which domain walls can be pinned by sub-10 nm constrictions. Controlled by shape anisotropy, we can switch the regions on either side of the...
Voltage-Controlled Spin Selection in a Magnetic Resonant Tunnelling Diode (2003)
Slobodskyy, A., Gould, C., Slobodskyy, T., Becker, C. R., Schmidt, G., Molenkamp, L. W.
We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their...
Quasi-ballistic transport in HgTe quantum-well nanostructures (2003)
Daumer, V., Golombek, I., Gbordzoe, M., Novik, E. G., Hock, V., Becker, C. R., ...
The transport properties of micrometer scale structures fabricated from high-mobility HgTe quantum-wells have been investigated. A special photoresist and Ti masks were used, which allow for the...
Electron-beam propagation in a two-dimensional electron gas (2002)
Novik, E. G., Buhmann, H., Molenkamp, L. W.
A quantum mechanical model based on a Green's function approach has been used to calculate the transmission probability of electrons traversing a two-dimensional electron gas injected and detected...
Electric Field Induced Kondo Tunneling Through Double Quantum Dot (2002)
Kiselev, M. N., Kikoin, K., Molenkamp, L. W.
It is shown that the resonance Kondo tunneling through a double quantum dot (DQD) with even occupation and singlet ground state may arise at a strong bias, which compensates the energy of...
Spin injection in the non-linear regime: band bending effects (2002)
Schmidt, G., Gould, C., Grabs, P., Lunde, A. M., Richter, G., Slobodskyy, A., ...
Semiconductor spintronics will need to control spin injection phenomena in the non-linear regime. In order to study these effects we have performed spin injection measurements from a dilute magnetic...
Large magnetoresistance effect due to spin-injection into a non-magnetic semiconductor (2001)
Schmidt, G., Richter, G., Grabs, P., Gould, C., Ferrand, D., Molenkamp, L. W.
A novel magnetoresistance effect, due to the injection of a spin-polarized electron current from a dilute magnetic into a non-magnetic semiconductor, is presented. The effect results from the...
Spin filtering and magnetoresistance in ballistic tunnel junctions (2001)
Egues, J. C., Gould, C., Richter, G., Molenkamp, L. W.
We theoretically investigate magnetoresistance (MR) effects in connection with spin filtering in quantum-coherent transport through tunnel junctions based on non-magnetic/semimagnetic...
Angle-Resolved Spectroscopy of Electron-Electron Scattering in a 2D System (2000)
Yanovsky, A. V., Predel, H., Buhmann, H., Gurzhi, R. N., Kalinenko, A. N., Kopeliovich, A. I., ...
Electron-beam propagation experiments have been used to determine the energy and angle dependence of electron-electron (ee) scattering a two-dimensional electron gas (2DEG) in a very direct manner by...
Predel, H., Buhmann, H., Molenkamp, L. W., Gurzhi, R. N., Kalinenko, A. N., Kopeliovich, A. I., ...
We have studied experimentally and theoretically the influence of electron-electron collisions on the propagation of electron beams in a two-dimensional electron gas for excess injection energies...
Schmidt, G., Molenkamp, L. W., Filip, A. T., Van Wees, B. J.
We have calculated the spin-polarization effects of a current in a two dimensional electron gas which is contacted by two ferromagnetic metals. In the purely diffusive regime, the current may indeed...
Probing the potential landscape inside a two-dimensional electron-gas (1999)
Koonen, J. J., Buhmann, H., Molenkamp, L. W.
We report direct observations of the scattering potentials in a two-dimensional electron-gas using electron-beam diffaction-experiments. The diffracting objects are local density-fluctuations caused...
The Thermopower of Quantum Chaos (1998)
Godijn, S. F., Moeller, S., Buhmann, H., Molenkamp, L. W., Van Langen, S. A.
The thermovoltage of a chaotic quantum dot is measured using a current heating technique. The fluctuations in the thermopower as a function of magnetic field and dot shape display a non-Gaussian...