Session W33: Focus Session: Spins in Narrow Gap Semiconductors

2:30 PM–5:30 PM, Thursday, March 13, 2008
Morial Convention Center Room: 224

Sponsoring Units: GMAG FIAP DMP
Chair: Berry Jonker, Naval Research Laboratory

Abstract ID: BAPS.2008.MAR.W33.15

Abstract: W33.00015 : Semiclassical Equations of Motion for Bloch Electrons in External Fields, Including Spin-Orbit Interaction.

5:18 PM–5:30 PM

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  W.C. Kerr
    (Wake Forest U.)

This talk considers an electron moving in a periodic potential with spin-orbit interaction and perturbed by external slowly varying electric field and uniform magnetic field. Superposition of the time-independent Bloch spinor states of the unperturbed Hamiltonian gives a wave packet state with both wavevector space and spin-orientation amplitude factors. The time-dependent variational principle produces equations of motion for the centers of the wave packet in both configuration and wavevector space and for the spin-orientation factors. For spinless electrons this procedure yields the familiar semiclassical equations of motion augmented by an orbital magnetic moment contribution to the Bloch band energy and an ``anomalous velocity'' proportional to a Berry curvature.\footnote{M. C. Chang \& Q. Niu, Phys. Rev. B {\bf{53}}, 7010 (1996)} The inclusion of spin-orbit interaction gives additional contributions to the velocity involving different Berry curvatures. One is a spin-dependent contribution to the magnetic moment, and another is an electric-dipole-like contribution that is also proportional to the spin operator.

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