Valley-Dependent Longitudinal Magnetoconductivity in Two-Dimensional Semiconductors

Recently the valley degrees of freedom of electrons in solids have attracted greater attention and revealing their roles in new electronic phenomena has become an important research theme. In this work, we use a quantum kinetic theory to study magnetotransport in two-dimensional semiconductors with valley degrees of freedom, such as monolayer transition-metal dichalcogenides. We find that, in a magnetic field applied perpendicular to the system, a longitudinal magnetoconductivity contribution that is odd in magnetic field and odd in valley index arises from the interplay between the momentum-space Berry curvature of Bloch electrons and the presence of a magnetic field. We take the effect of short-range disorder scattering into account using a Born approximation, which corresponds to a ladder-diagram approximation vertex correction, and find that the vertex correction enhances the linear magnetoconductivity. The valley-dependent longitudinal magnetoconductivity can be measured by studying the sensitivity of magnetoresistance to valley polarization, or by using Kerr microscopy to detect current-induced valley polarization near a gate-induced inhomogeneity.