Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 95: Spintronics: Mobile Electrons and Holes (jointly with HL, MA)

TT 95.6: Talk

Thursday, March 19, 2015, 11:30–11:45, ER 164

Hole spin coherence in coupled GaAs/AlAs quantum wells — •Christian Gradl, Johannes Holler, Michael Kempf, Dieter Schuh, Dominique Bougeard, Christian Schüller, and Tobias Korn — Universität Regensburg, D-93040 Regensburg, Germany

We performed time-resolved Kerr rotation (TRKR) measurements on an undoped [113]-grown double quantum well (QW) structure to resolve the spin dynamics of hole ensembles at low temperatures. Our gated system consists of two QWs with different well widths, which we use for the spatial separation of the optically excited electron-hole pairs. Thus, we are able to create hole ensembles with spin dephasing times of several hundreds of picoseconds in the broader QW without any doping.

This allowed an unexpected observation of a non-precessing component in the TRKR signal in the presence of an applied magnetic field perpendicular to the spin polarization. These measurements also show the non-precessing component to be a part of the optically generated hole spin polarization. This effect might arise from a tilting of the quantization axis with respect to the applied magnetic field due to a large anisotropy between the in- and out-of-plane hole g factor.