SPP1285: Spin-dependent electron transport in GaAs/AlGaAs nanostructures

The aim of this project within the DFG priority programm SPP1285 "Semiconductor Spinelectronics" is to investigate spin-dependent ballistic transport in nanoscale GaAs/AlGaAs field-effect heterostructures. Starting materials are modulation doped heterostructures with two-dimensional electron gases of high mobilities (> 106 cm2/Vs) from which Aharonov-Bohm ring structures are prepared by electron-beam lithography and wet-chemical etching. Four-terminal measurements of current and voltage characteristics are taken as a function of top voltages and magnetic fields at low temperatures (< 4.2 K). Local top and side gates will be used to control the electron densities in the electron wave guides of the ring. The amplitude and phase of the Aharonov-Bohm conductance oscillations will be measured for different operating modes of the injecting quantum point contact. Up-to-date, the transport in the mode occupation below the first mode of a quantum point contact is discussed with spin-related mechanisms and remains an unresolved issue.