Publications (33)
Remote-doping scattering and the local field corrections in the 2D electron system in a modulation-doped Si/SiGe quantum well
V. T. Dolgopolov, E. V. Deviatov, A. A. Shashkin +4
The small, about 30% magnetoresistance at the onset of full spin polarization in the 2D electron system in a modulation-doped Si/SiGe quantum well gives evidence that it is the rem…
Independent magnetization behavior of a ferromagnetic metal/semiconductor hybrid system
S. Mark, C. Gould, K. Pappert +4
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 s…
Coincidence of Superparamagnetism and perfect quantization in the Quantum Anomalous Hall state
S. Grauer, S. Schreyeck, M. Winnerlein +3
Topological insulators doped with transition metals have recently been found to host a strong ferromagnetic state with perpendicular to plane anisotropy as well as support a quantu…
Epitaxy and Structural Properties of (V,Bi,Sb)Te Layers Exhibiting the Quantum Anomalous Hall Effect
M. Winnerlein, S. Schreyeck, S. Grauer +5
The influence of Sb content, substrate type and cap layers on the quantum anomalous Hall effect observed in V-doped (Bi,Sb)Te magnetic topological insulators is investigate…
Characterising the Surface Resistance of Laser-Treated LHC Beam Screens with the Shielded Pair Method
P. KrkotiÄ, E. Bez, K. Brunner +6
The presence of strong electron clouds in the quadrupole magnetic field regions of the Large Hadron Collider (LHC) leads to considerable heating that poses challenges for the cryog…
Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions
Ts. Naydenova, P. Dürrenfeld, K. Tavakoli +6
We report the observation of tunneling anisotropic magnetothermopower, a voltage response to a temperature difference across an interface between a normal and a magnetic semiconduc…
Tunneling Anisotropic Magnetoresistance: A spin-valve like tunnel magnetoresistance using a single magnetic layer
C. Gould, C. Rüster, T. Jungwirth +6
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…
Non-thermal photocoercivity effect in a ferromagnetic semiconductor
G. V. Astakhov, H. Hoffmann, V. L. Korenev +7
We report a photoinduced change of the coercive field, i.e., a photocoercivity effect (PCE), under very low intensity illumination of a low-doped (Ga,Mn)As ferromagnetic semiconduc…
Detailed transport investigation of the magnetic anisotropy of (Ga,Mn)As
K. Pappert, C. Gould, M. Sawicki +4
This paper discusses transport methods for the investigation of the (Ga,Mn)As magnetic anisotropy. Typical magnetoresistance behaviour for different anisotropy types is discussed,…
Antiferromagnetic order in MnBi2Te4 films grown on Si(111) by molecular beam epitaxy
N. Liu, S. Schreyeck, K. M. Fijalkowski +4
MnBi2Te4 has recently been predicted and shown to be a magnetic topological insulator with intrinsic antiferromagnetic order. However, it remains a challenge to grow stoichiometric…
Quantum transport and mobility spectrum of topological carriers in (001) SnTe/PbTe heterojunctions
D. Ånieżek, JarosÅaw Wróbel, M. Kojdecki +6
Measurements of magnetotransport in SnTe/PbTe heterojunctions grown by the MBE technique on (001) undoped CdTe substrates were performed. At low magnetic fields, quantum correction…
Kinetic limitation of chemical ordering in BiTeSe layers grown by molecular beam epitaxy
S. Schreyeck, K. Brunner, A. Kirchner +7
We study the chemical ordering in BiTeSe grown by molecular beam epitaxy on Si substrates. We produce films in the full composition range from x = 0 to 3, and deter…
Quantum-dot-based optical polarization conversion
G. V. Astakhov, T. Kiessling, A. V. Platonov +6
We report circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. The polarization conversion occurs under continuous wave excit…
Transport Characterization of the Magnetic Anisotropy of (Ga,Mn)As
K. Pappert, S. Hümpfner, J. Wenisch +4
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…
Effect of dye doping on the charge carrier balance in PPV light emitting diodes as measured by admittance spectroscopy
I. N. Hulea, R. F. J. van der Scheer, H. B. Brom +3
Dye doping is a promising way to increase the spectral purity of polymer light-emitting diodes (LEDs). Here we analyze the frequency and field dependence of the complex admittance…
Molecular beam epitaxy of high structural quality Bi2Se3 on lattice matched InP(111) substrates
S. Schreyeck, N. V. Tarakina, G. Karczewski +7
Epitaxial layers of the topological insulator Bi2Se3 have been grown by molecular beam epitaxy on laterally lattice-matched InP(111)B substrates. High resolution X-ray diffraction…
Zero external magnetic field quantum standard of resistance at the 10-9 level
D. K. Patel, K. M. Fijalkowski, M. Kruskopf +10
The quantum anomalous Hall effect holds promise as a disruptive innovation in condensed matter physics and metrology, as it gives access to Hall resistance quantization in terms of…
Lateral magnetic anisotropy superlattice out of a single (Ga,Mn)As layer
R. G. Dengel, C. Gould, J. Wenisch +3
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 w…
Exploiting Locally Imposed Anisotropies in (Ga,Mn)As: a Non-volatile Memory Device
K. Pappert, S. Hümpfner, C. Gould +4
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 dev…
Control of magnetic anisotropy in (Ga,Mn)As by lithography-induced strain relaxation
J. Wenisch, C. Gould, L. Ebel +7
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 sophis…
Suppressing twin formation in Bi2Se3 thin films
N. V. Tarakina, S. Schreyeck, M. Luysberg +8
The microstructure of Bi2Se3 topological-insulator thin films grown by molecular beam epitaxy on InP(111)A and InP(111)B substrates that have different surface roughnesses has been…
Lithographic engineering of anisotropies in (Ga,Mn)As
S. Hümpfner, M. Sawicki, K. Pappert +6
The focus of studies on ferromagnetic semiconductors is moving from material issues to device functionalities based on novel phenomena often associated with the anisotropy properti…
Prevention of core particle depletion in stellarators by turbulence
H. Thienpondt, J. M. GarcÃa-Regaña, I. Calvo +11
In reactor-relevant plasmas, neoclassical transport drives an outward particle flux in the core of large stellarators and predicts strongly hollow density profiles. However, this t…
Scaling of the Quantum Anomalous Hall Effect as an Indicator of Axion Electrodynamics
S. Grauer, K. M. Fijalkowski, S. Schreyeck +5
We report on the scaling behavior of V-doped (Bi,Sb)Te samples in the quantum anomalous Hall regime for samples of various thickness. While previous quantum anomalous Hall…
Fully electrically read-write device out of a ferromagnetic semiconductor
S. Mark, P. Dürrenfeld, K. Pappert +4
We report the realization of a read-write device out of the ferromagnetic semiconductor (Ga,Mn)As as the first step to fundamentally new information processing paradigm. Writing th…
An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material
C. Gould, S. Mark, K. Pappert +14
This paper reports on a detailed magnetotransport investigation of the magnetic anisotropies of (Ga,Mn)As layers produced by various sources worldwide. Using anisotropy fingerprint…
Current Assisted Magnetization Switching in (Ga,Mn)As Nanodevices
C. Gould, K. Pappert, C. Rüster +6
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 u…
Magneto-optics of massive Dirac fermions in bulk Bi2Se3
M. Orlita, B. A. Piot, G. Martinez +13
We report on magneto-optical studies of Bi2Se3, a representative member of the 3D topological insulator family. Its electronic states in bulk are shown to be well described by a si…
Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots
T. Kiessling, A. V. Platonov, G. V. Astakhov +6
We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis e…
Magnetization-Switched Metal-Insulator Transition in a (Ga,Mn)As Tunnel Device
K. Pappert, M. J. Schmidt, S. Hümpfner +6
We observe the occurrence of an Efros-Shklovskii gap in (Ga,Mn)As based tunnel junctions. The occurrence of the gap is controlled by the extent of the hole wave-function on the Mn…
1500-fold Tunneling Anisotropic Magnetoresistance in a (Ga,Mn)As stack
C. Rüster, C. Gould, T. Jungwirth +6
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 depende…
Spin-photocurrent in p-SiGe quantum wells under terahertz laser irradiation
V. V. Bel'kov, S. D. Ganichev, Petra Schneider +7
A detailed study of the circular photogalvanic effect (CPGE) in SiGe structures is presented. It is shown that the CPGE becomes possible due to the built-in asymmetry of quantum we…
Any Axion Insulator Must be a Bulk Three-Dimensional Topological Insulator
K. M. Fijalkowski, N. Liu, M. Hartl +11
In recent attempts to observe axion electrodynamics, much effort has focused on trilayer heterostructures of magnetic topological insulators, and in particular on the examination o…