Theoretical study of spin-dependent transport in WSe$_2$-based vertical spin valves

TL;DR

This theoretical study explores spin-dependent transport in WSe$_2$-based vertical spin valves, revealing oscillatory magnetoresistance and interference effects that inform spintronic device design.

Contribution

It introduces a transfer-matrix approach to analyze magnetoresistance oscillations and interference effects in WSe$_2$ spin valves, advancing understanding of their tunable properties.

Findings

Magnetoresistance oscillates with WSe$_2$ thickness near the valence-band maximum.

Gate voltage and exchange fields significantly influence magnetoresistance.

Fabry-Pérot-like interference can induce negative magnetoresistance.

Abstract

We theoretically investigate spin-dependent transport in a TMD-based vertical spin valve, taking WSe$_2$ as a representative example. Using effective Hamiltonians for the heterostructure and the Landauer formula, we derive the transmission and reflection coefficients within a transfer-matrix approach. The calculated magnetoresistance shows an oscillatory dependence on the WSe$_2$ thickness when the Fermi level is tuned near the valence-band maximum. The effects of gate voltage and exchange fields on the magnetoresistance are further analyzed. We also identify a Fabry-P\'erot-like interference contribution to the magnetoresistance, which can enhance or even induce negative magnetoresistance in certain thickness regimes. Our results provide a qualitative understanding of the negative magnetoresistance observed in WSe$_2$-based spin valves and may offer useful insights for the design of tunable spintronic devices.