Tuesday, January 15, 2013

1301.2784 (Guru Khalsa et al.)

Theory of t2g electron-gas Rashba interactions    [PDF]

Guru Khalsa, Byounghak Lee, A. H. MacDonald
The spin-degeneracy of Bloch bands in a crystal can be lifted when spin-orbit (SO) coupling is present and inversion symmetry is absent. In two-dimensional electron systems (2DES) spin-degeneracy is lifted by Rashba interaction terms - symmetry invariants that are scalar products of spin and orbital axial vectors. Rashba interactions are symmetry allowed whenever a 2DES is not invariant under reflections through the plane it occupies. In this paper, we use a tight-binding model informed by ab initio electronic structure calculations to develop a theory of Rashba splitting in the t2g bands of the two- dimensional electron systems formed at cubic perovskite crystal surfaces and interfaces. We find that Rashba splitting in these systems is due to atomic-like on-site SO interactions combined with processes in which t2g electrons change orbital character when they hop between metal sites. These processes are absent in a cubic environment and are due primarily to polar lattice distortions which alter the metal-oxygen-metal bond angle.
View original: http://arxiv.org/abs/1301.2784

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