Spin- and valley-dependent magneto-optical properties of MoS2

TL;DR

This study explores how magnetic fields influence the spin and valley properties of electrons in MoS2, revealing how light polarization can selectively excite specific electron states and how higher-order effects enable detailed spectroscopic measurements.

Contribution

It provides a detailed analysis of magneto-optical excitations in MoS2, highlighting the role of higher-order band corrections and proposing methods to measure fundamental electronic gaps.

Findings

Valley and spin polarization can be induced via light in MoS2.

Higher-order band effects enable additional optical transitions.

Inter-Landau-level transitions can measure the material's electronic gaps.

Abstract

We investigate the behavior of low-energy electrons in two-dimensional molybdenum disulfide when submitted to an external magnetic field. Highly degenerate Landau levels form in the material, between which light-induced excitations are possible. The dependence of excitations on light polarization and energy is explicitly determined, and it is shown that it is possible to induce valley and spin polarization, i.e. to excite electrons of selected valley and spin. Whereas the effective low-energy model in terms of massive Dirac fermions yields dipole-type selection rules, higher-order band corrections allow for the observation of additional transitions. Furthermore, inter-Landau-level transitions involving the n=0 levels provide a reliable method for an experimental measurement of the gap and the spin-orbit gap of molybdenum disulfide.