2013/11/05 by K. Kośmider, J. W. González, J. Fernández-Rossier · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.88.245436
published as Phys. Rev. B 88, 245436 (2013) · 8 pages, 4 figures
arxiv created 2013/11/05 · arxiv updated 2014/01/01
We study the conduction band spin splitting that arises in transition metal dichalcogenide (TMD) semiconductor monolayers such as MoS2, MoSe2, WS2 and WSe2 due to the combination of spin-orbit coupling and lack of inversion symmetry. Two types of calculation are done. First, density functional theory (DFT) calculations based on plane waves and pseudo potentials that yield large splittings, between 3 and 30 meV. Second, we derive a tight-binding model, that permits to address the atomic origin of the splitting. The basis set of the model is provided by the maximally localized Wannier orbitals, obtained from the DFT calculation, and formed by 11 atomic-like orbitals corresponding to 5d and 3p orbitals of the transition metal (W,Mo) and chalcogenide (S,Se) atoms respectively. In the resulting Hamiltonian we can independently change the atomic spin-orbit coupling constant of the two atomic species at the unit cell, which permits to analyse their contribution to the spin splitting at the high symmetry points. We find that ---in contrast to the valence band--- both atoms give comparable contributions to the conduction band splittings. Given that these materials are most often n-doped, our findings are important for developments in TMD spintronics.