Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 24: Poster Session: Ge/Si/SiC / III - V Semiconductors
HL 24.3: Poster
Monday, March 26, 2012, 16:00–19:00, Poster D
Hole spin dynamics in 2D GaAs/AlGaAs systems at low temperatures — •Michael Kugler1, Kamil Korzekwa2, Pawel Machnikowski2, Christian Gradl1, Stephan Furthmeier1, Michael Griesbeck1, Marika Hirmer1, Dieter Schuh1, Werner Wegscheider3, Tillmann Kuhn4, Christian Schüller1 und Tobias Korn1 — 1Universität Regensburg, D-93040 Regensburg, Germany — 2Wroclaw University of Technology, 50-370 Wroclaw, Poland — 3ETH Zurich, 8093 Zurich, Switzerland — 4Westfälische Wilhelms-Universität, D-48149 Münster, Germany
We performed time-resolved Kerr rotation measurements (TRKR) on p-doped GaAs/AlGaAs single wells to resolve the spin dynamics of hole ensembles, confined in so-called natural quantum dots. For long spin lifetimes, we employ the resonant spin amplification (RSA) technique. Hole spins in such systems may be a viable alternative to electron spins for solid-state quantum-bit systems. A key requirement for this is the generation of a resident hole spin polarization (RHSP).
Here, we report on a novel mechanism that leads to a RHSP after optical excitation. It is driven by quick relaxation of the hole spins in the first few ps after excitation. The recombination of electrons and holes with matching spin polarization leads then to a RHSP pointing in the opposite direction than the optically generated spins. It is greatly enhanced by increased temperature, excitation density and excess carrier energy provided by detuning the laser from resonant excitation. The interconnected e/h spin dynamics leading to this behavior are well reproduced theoretically for TRKR as well as for RSA setups.