Spin transport in n-type single-layer transition metal dichalcogenides

TL;DR

This paper theoretically investigates spin transport in n-type single-layer transition metal dichalcogenides, revealing unique Hanle curve features due to valley asymmetry and spin-orbit coupling effects.

Contribution

It provides a theoretical analysis of the Hanle effect in TMDs, highlighting how valley asymmetry influences spin dynamics and the shape of Hanle curves.

Findings

Hanle shape differs for normal and parallel magnetic field orientations.

Two peaks in Hanle curve indicate slow intervalley scattering.

Cusp at zero field signifies a slow-decaying valley-asymmetric spin mode.

Abstract

Valley asymmetry of the electron spectrum in transition metal dichalcogenides (TMDs) originates from the spin-orbit coupling. Presence of spin-orbit fields of opposite signs for electrons in K and K' valleys in combination with possibility of intervalley scattering result in a nontrivial spin dynamics. This dynamics is reflected in the dependence of nonlocal resistance on external magnetic field (the Hanle curve). We calculate theoretically the Hanle shape in TMDs. It appears that, unlike conventional materials without valley asymmetry, the Hanle shape in TMDs is different for normal and parallel orientations of the external field. For normal orientation, it has two peaks for slow intervalley scattering, while, for fast intervalley scattering the shape is usual. For parallel orientation, the Hanle curve exhibits a cusp at zero field. This cusp is a signature of a slow-decaying valley-asymmetric mode of the spin dynamics.