Geometric band properties in strained monolayer transition metal dichalcogenides using simple band structures (1906.06146v2)

Abstract: Monolayer transition metal dichalcogenides (TMDs) bare large Berry curvature hotspots readily exploitable for geometric band effects. Tailoring and enhancement of these features via strain is an active research direction. Here, we consider spinless two- and three-band, and spinful four-band models capable to quantify Berry curvature and orbital magnetic moment of strained TMDs. First, we provide a $k\cdot p$ parameter set for MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$ in the light of the recently released ab initio and experimental band properties. Its validity range extends from $K$ valley edge to about hundred millielectron volts into valence and conduction bands for these TMDs. To expand this over a larger part of the Brillouin zone, we incorporate strain to an available three-band tight-binding Hamiltonian. With these techniques we demonstrate that both the Berry curvature and the orbital magnetic moment can be doubled compared to their intrinsic values by applying typically a 2.5% biaxial tensile strain. These simple band structure tools can find application in the quantitative device modeling of the geometric band effects in strained monolayer TMDs.