Spintronics with semiconductor nanowires

The basic ingredients for spintronics using semiconductor nanowires are discussed. For spin manipulation spin-orbit coupling is employed. In this respect the effect of the Rashba and Dresselhaus contributions are investigated. The strength of spin-orbit coupling is extracted by measuring the weak anti-localization effect and comparing the experimental results to a theoretical model. On nanowires covered with a set of narrow gate fingers, quantized conductance is observed. By analyzing the transconductance the Zeeman spin splitting is determined at various magnetic fields. It is found that the gyromagnetic factor is lowered due to the reduced effect of spin-orbit coupling. Confinement-induced quenching of the orbital motion results in a modified subband-dependent Lande g-factor. For strong confinement a pronounced g-factor enhancement related to Coulomb exchange interaction is reported. Indications for the formation of a helical gap are found, which is relevant for the realization of Majorana states.