Year: 2013
Type: article
Abstract: We study the conduction band spin splitting that arises in transition metal dichalcogenide (TMD) semiconductor monolayers such as MoS${}_{2}$, MoSe${}_{2}$, WS${}_{2}$, and WSe${}_{2}$ 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 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 atomiclike orbitals corresponding to $d$ and $p$ 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 analyze 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.
Source: Physical Review B
Institution: International Iberian Nanotechnology Laboratory
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
Award: G5092384331
OpenAlex ID: W2042688191