Spin transfer torque and anisotropic conductance in spin orbit coupled graphene

TL;DR

This paper theoretically investigates how spin-orbit coupling in graphene affects spin-transfer torque and conductance, revealing anisotropic behaviors and conditions for zero torque, with implications for experimental studies of proximity-induced SOC.

Contribution

It introduces a theoretical model showing how SOC modifies spin-transfer torque and conductance anisotropically in graphene-based junctions with ferromagnetic regions.

Findings

SOC causes anisotropic modifications in STT and conductance.

Perfect transmission occurs in the Klein regime with zero STT.

SOC induces nonzero STT due to band structure changes.

Abstract

We theoretically study spin-transfer torque (STT) in a graphene system with spin-orbit coupling (SOC). We consider a graphene-based junction where the spin-orbit coupled region is sandwiched between two ferromagnetic (F) segments. The magnetization in each ferromagnetic segment can possess arbitrary orientations. Our results show that the presence of SOC results in anisotropically modified STT, magnetoresistance, and charge conductance as a function of relative magnetization misalignment in the F regions. We have found that within the Klein regime, where particles hit the interfaces perpendicularly, the spin-polarized Dirac fermions transmit perfectly through the boundaries of an F-F junction (i.e., with zero reflection), regardless of the relative magnetization misalignment and exert zero STT. In the presence of SOC, however, due to band structure modification, a nonzero STT reappears. Our findings can be exploited for experimentally examining proximity-induced SOC into a graphene system