Monolayer MoS2: trigonal warping, "\Gamma-valley", and spin-orbit coupling effects

TL;DR

This paper develops a refined low-energy Hamiltonian for monolayer MoS2 that includes trigonal warping, Gamma-valley, and spin-orbit effects, enhancing understanding of its electronic properties.

Contribution

It introduces a combined ab-initio and k.p theory approach to accurately model monolayer MoS2, capturing features missed by previous models.

Findings

Accurate modeling of trigonal warping in MoS2

Identification of Gamma-valley effects

Enhanced understanding of spin-splitting in conduction band

Abstract

We use a combined ab-initio calculations and k.p theory based approach to derive a low-energy effective Hamiltonian for monolayer MoS2 at the K point of the Brillouin zone. It captures the features which are present in first-principles calculations but not explained by the theory of Xiao et al. [Phys Rev Lett 108, 196802 (2012)], namely the trigonal warping of the valence and conduction bands, the electron-hole symmetry breaking, and the spin-splitting of the conduction band. We also consider other points in the Brillouin zone which might be important for transport properties. Our findings lead to a more quantitative understanding of the properties of this material in the ballistic limit.