Spin Orbit Interaction in Inversion-Symmetric Semiconductors: SrTiO3 and group IV

Low-energy effective spin-orbit Hamiltonians have proved effective at describing the effect of spin-orbit interactions on populations of polarized carriers in direct-gap semiconductors such as gallium arsenide. No similar low-energy Hamiltonians are available for materials with inversion symmetry, such as cubic oxides or group-IV semiconductors. In order to construct such low-energy Hamiltonians we have calculated the electronic band structure of strontium titanate, a perovskite material which has recently been used to make high-density two-dimensional electron gases, using a tight-binding electronic structure with atomic spin-orbit interactions. We have also calculated the band structures of several group-IV semiconductors, including germanium, silicon, and diamond. An expression for the effective spin-orbit interaction in the conduction band of these materials has been derived, and calculated for these materials. The symmetry properties of this effective spin-orbit interaction tensor will also be discussed. This work was supported by an ARO MURI.