Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 42: Optical Properties of Quantum dots: Theory and Simulation

HL 42.1: Vortrag

Donnerstag, 28. Februar 2008, 09:30–09:45, EW 201

Gauge invariant k.p envelope function theory and g-factors in quantum dots — •Till Andlauer, Richard Morschl, and Peter Vogl — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching

We present a gauge invariant real space discretization scheme that includes magnetic fields nonperturbatively in the framework of the multiband k.p envelope function theory. Our procedure is based on Wilson's formulation of gauge theories [1]. The magnetic field couples to the envelope functions via phase factors that result from spatial discretization of the gauge covariant derivative. These phase factors contain a discretized curve integral over the vector potential. In addition, the carrier's spin couples to the magnetic field via a Zeeman-term. In the case of infinitesimal grid spacings, our method becomes equivalent to the minimal substitution method. Applying our procedure, we calculate effective electron and hole g-factors of InAs/InP nanowire dots as a function of dot size and magnetic field direction. We obtain excellent agreement with experimental data [2] and show that the changes in g-factors correlate well with the spatial extent of the wave functions. Furthermore, we investigate the influence of strain and high magnetic fields on the g-factors. In the latter case, we find nonlinear Zeeman splittings and strongly deformed eigenstates. [1] K. G. Wilson, Phys. Rev. D 10, 2445 (1974). [2] M. T. Björk et al., Phys. Rev. B 72, 201307(R) (2005).