Hamburg 2001 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 36: Spinabh
ängiger Transport
HL 36.4: Vortrag
Donnerstag, 29. März 2001, 16:15–16:30, S2
First principles studies of Rashba effect in superlattices — •Jacek A. Majewski and Peter Vogl — Walter Schottky Institute, TU Munich, Am Coulombwall 3, D-85748 Garching
We present first-principles calculations of k-linear zero-field spin splittings of the lowest conduction bands in semiconductor heterostructures and superlattices. One contribution to this type of spin-splitting is the Rashba term [1]. However, its magnitude, physical origin, and dependence on macroscopic electric fields or interfaces have remained controversial [1]. We have studied the spin splitting of conduction bands by performing fully relativistic pseudopotential local density functional calculations of lattice matched GaAs/AlGaAs as well as InP/AlAsSb and InP/GaAsSb strained layer superlattices. For superlattices with D2d symmetry, the Rashba effect disappears and the k-linear zero-field spin splittings are entirely caused by the Bulk Inversion Asymmetry (BIA) term that originates from the bulk Dresselhaus term. The corresponding BIA constants αBIA are of the order of 0.03 - 0.10 eV Å, and we find them to be nearly independent on the superlattice period. Furthermore, we find external electric fields to induce Rashba constants αR that are an order of magnitude smaller than αBIA. We predict large Rashba constants (of the order of αBIA) to occur only in no-common-atom superlattices with interface asymmetry. Altogether, these results demonstrate that the Rashba effect does not require the presence of a macroscopic electric field and the magnitude of the Rashba constant is controlled by local rather than by macroscopic fields.
[1] P. Pfeffer, Phys. Rev. B 59, 15902 (1999), and references therein