Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 29: Spintronik IV
HL 29.2: Vortrag
Samstag, 5. März 2005, 15:15–15:30, TU P270
Spin-orbit coupling parameters for electrons and holes in III-V semiconductors — •R Scholz1, J.-M. Jancu2, E.A. de Andrada e Silva2,3, and G.C. La Rocca2 — 1Institut für Physik, Technische Universität Chemnitz, Chemnitz, Germany — 2Scuola Normale Superiore and INFM, Piazza dei Cavalieri 7, Pisa, Italy — 3Instituto Nacional de Pesquisas Espaciais, 12201 Sao Jose dos Campos, Sao Paulo, Brasil
Multi-band k · p Hamiltonians depend on both momentum and spin-orbit coupling parameters whose values turn out to be crucial for the spin splittings and the anisotropy of both conduction and valence bands. We report on a precise determination of the k · p parameters required for an effective 14-band bulk Hamiltonian for III-V semiconductors [1] by using an improved tight-binding (TB) model [2]. The TB calculations are performed in an sp3d5s* nearest neighbor model including spin-orbit coupling, where the optimized parameters reproduce the experimental band energies all around the Brillouin zone. The 14-band model is obtained from a Löwdin renormalization of the 40-band TB Hamiltonian and a subsequent Taylor series expansion around Γ. Our new values for the off-diagonal spin-orbit splitting between the Γ4 valence and conduction states and for the k3 Dresselhaus spin splitting of the conduction band are compared to previous results. The differences between the TB band structure and the k · p expansion define the range of applicability of the latter, indicating requirements for experimental tests of the theory.
[1] P. Pfeffer and W. Zawadzki, Phys. Rev. B 53, 12813 (1996).
[2] J.-M. Jancu, R. Scholz, F. Beltram, and F. Bassani, Phys. Rev. B 57, 6493 (1998).