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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.37: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Observing and controlling hole spin dynamics in 2D hole systems at sub-Kelvin temperatures — •Michael Kugler, Tobias Korn, Sebastian Fehringer, Anton Wagner, Robert Schulz, Christian Gerl, Marika Kubova, Dieter Schuh, Werner Wegscheider, and Christian Schüller — Institut für Experimentelle und Angewandte Physik, Universität Regensburg

In recent years, due to the rapidly growing field of semiconductor spintronics, much interest has been focused on the spin dynamics of electrons in semiconductors, while the hole spin dynamics have not been investigated as rigorously. Here, we report on time-resolved Faraday rotation (TRFR) measurements on 2D hole systems within p-doped GaAs quantum wells (QWs) of different width. In the TRFR measurements, the sample is excited by a circularly-polarized laser pulse tuned to the exciton energy. A large in-plane magnetic field is applied within the sample plane, causing a precession of the photocreated carriers. At sample temperatures below 4 K, superimposed on the electron spin dynamics, we observe the long-lived precession of hole spins, which becomes even more pronounced at 400 mK. In the narrower QWs, the energy splitting between light and heavy hole is increased, leading to a reduced hole state mixing, which increases the hole spin lifetime further. In a gated sample, we observe a pronounced shift of the hole precession frequency as the gate voltage is changed. This indicates that the hole g factor may be strongly dependent on the growth-axis symmetry of the QW, which can be changed by the applied voltage.