Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 29: Spinabh
ängiger Transport I
HL 29.2: Vortrag
Mittwoch, 10. März 2004, 15:30–15:45, H13
Spin Polarization of Two-Dimensional Hole Systems — •R. Winkler1, E. Tutuc2, S. Melinte2, M. Shayegan2, D. Wasserman2, and S. A. Lyon2 — 1Institut für Festkörperphysik, Abt. Nanostrukturen, Universität Hannover — 2Department of Electrical Engineering, Princeton University
Hole systems are conceptually different from electron systems due to the fact that hole states have an effective spin j=3/2. Subband quantization in quasi two-dimensional (2D) systems yields a quantization of angular momentum with z component of angular momentum m= ± 3/2 for the heavy hole (HH) states and m= ± 1/2 for the light hole (LH) states. The quantization axis of angular momentum that is enforced by HH-LH splitting is pointing perpendicular to the plane of the quasi 2D system. On the other hand, in general the effective Hamiltonians for B=0 spin splitting and Zeeman splitting in an in-plane magnetic field B>0 tend to orient the spin vector parallel to the plane of the quasi 2D system. Obviously it is not possible to have a “second quantization axis of angular momentum” on top of the perpendicular quantization axis due to HH-LH splitting. We will thus discuss how spin splitting and spin polarization in quasi 2D HH systems compete with HH-LH splitting. We will compare the results of calculations and experiments showing the depopulation of the upper spin subband in quasi 2D HH systems as a function of an in-plane magnetic field. We will demonstrate theoretically and experimentally that the shape of the confinement potential greatly affects the spin subband depopulation field.