paper

Tunable spin polarization and electronic structure of bottom-up synthesized MoSiN materials

arXiv:2105.02739 · doi:10.1103/PhysRevB.104.L201112

Abstract

Manipulation of spin-polarized electronic states of two-dimensional (2D) materials under ambient conditions is necessary for developing new quantum devices with small physical dimensions. Here, we explore spin-dependent electronic structures of ultra-thin films of recently introduced 2D synthetic materials MSiZ (M = Mo or W and Z = N or As) using first-principles modeling. Stacking of MSiZ monolayers is found to generate dynamically stable bilayer and bulk materials with thickness-dependent properties. When spin-orbit coupling (SOC) is included in the computations, MSiN monolayers display indirect bandgaps and large spin-split states at the and symmetry points at the corners of the Brillouin zone with nearly 100\% spin polarization. The spins are locked in opposite directions along an out-of-the-plane direction at and , leading to spin-valley coupling effects. As expected, spin polarization is absent in the pristine bilayers due to the presence of inversion symmetry, but it can be induced via an external out-of-plane electric field much like the case of Mo(W)S bilayers. A transition from an indirect to a direct bandgap can be driven by replacing N by As in MSi(N, As) monolayers. Our study indicates that the MSiZ materials can provide a viable alternative to the MoS class of 2D materials for valleytronics and optoelectronics applications.

6 pages, 5 figures, Accepted version in PRB:Letters

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