Christian Gerl

Rashba and Dresselhaus spin splittings in semiconductor quantum wells measured by spin photocurrents

The spin-galvanic effect and the circular photogalvanic effect induced by terahertz radiation are applied to determine the relative strengths of Rashba and Dresselhaus band spin splitting in 001-grown GaAs and InAs based two dimensional electron systems. We observed that shifting the -doping plane from one side of the quantum well to the other results in a change of sign of the photocurrent caused by Rashba spin splitting while the sign of the Dresselhaus term induced photocurrent remains. The measurements give the necessary feedback for technologists looking for structures with equal Rashba and Dresselhaus spin splittings or perfectly symmetric structures with zero Rashba constant.

Nonlinear growth in the amplitude of radiation-induced magnetoresistance oscillations

We report the observation of inverse magnetic field periodic, radiation-induced magnetoresistance oscillations in GaAs/AlGaAs heterostructures prepared in W. Wegscheiders group, compare their characteristics with similar oscillations in V. Umanskys material, and describe the lineshape variation vs the radiation power,

Zero-bias spin separation

P

Bias dependent inversion of tunneling magnetoresistance in Fe/GaAs/Fe tunnel junctions

, in the two systems. We find that the radiation-induced oscillatory resistance,

Carbon-doped symmetric GaAs∕AlGaAs quantum wells with hole mobilities beyond 106cm2∕Vs

\ensuremath{\Delta}{R}_{xx}

Engineering ultralong spin coherence in two-dimensional hole systems at low temperatures

, in both materials, can be described by

Spin photocurrents and the circular photon drag effect in (110)-grown quantum well structures

\ensuremath{\Delta}{R}_{xx}=\ensuremath{-}A\text{ }\text{exp}(\ensuremath{-}\ensuremath{\lambda}/B)\text{sin}(2\ensuremath{\pi}F/B)

Spin photocurrents in (110)-grown quantum well structures

, where

Spin-orbit splitting and effective masses in p-type GaAs two-dimensional hole gases

A

Characterization of spin-orbit interactions of GaAs heavy holes using a quantum point contact.

is the amplitude,