Spin-dependent Refraction at the Atomic Step of Transition-metal Dichalcogenides

TL;DR

This paper proposes a theoretical mechanism where spin-unpolarized electrons are split into different directions at an atomic boundary in transition-metal dichalcogenides due to spin-orbit interaction and Fermi surface effects.

Contribution

It introduces a novel spin-dependent refraction phenomenon at monolayer-bilayer boundaries in transition-metal dichalcogenides, enabling spin separation without magnetic materials.

Findings

Up-spin and down-spin electrons refract in opposite directions.

The effect arises from spin-orbit coupling and Fermi surface warping.

Potential application as a spin splitter device.

Abstract

We theoretically propose a novel spin-dependent electronic transport mechanism in which the spin-unpolarized electron beam is split into different directions depending on spins at an atomic domain boundary in non-magnetic material. Specifically, we calculate the electronic transmission across a boundary between monolayer and bilayer of the transition metal dichalcogenide, and demonstrate that up-spin and down-spin electrons entering the boundary are refracted and collimated to opposite directions. The phenomenon is attributed to the strong spin-orbit interaction, the trigonally-warped Fermi surface, and the different crystal symmetries between the monolayer and bilayer systems. The spin-dependent refraction suggests a potential application for a spin splitter, which spatially separates up-spin and down-spin electrons simply by passing the electric current through the boundary.