Spin Transport and Spin Pump in Graphene-like Materials: Effect of tilt in Dirac cones

TL;DR

This paper investigates how tilting Dirac cones in graphene-like materials affects spin transport, revealing that tilt can tune, reverse, or nullify spin currents, offering new control mechanisms for spintronics applications.

Contribution

It introduces a generalized scattering approach to analyze spin transport in tilted Dirac materials and demonstrates controllability of spin currents via tilt manipulation.

Findings

Tilt modifies the oscillation period of spin current.

Spin conductance can be tuned by Dirac cone tilt.

Pure spin current reversal is achievable through tilt variation.

Abstract

We study the spin transport phenomena in two-dimensional graphene-like materials with arbitrary tilted Dirac cones. The tilt arises due to next-nearest hopping when the bottom of the conduction band and top of the valence band does not simultaneously coincide at Dirac point. We consider normal-ferromagnetic-normal (N-F-N) junction of the materials and using the generalized scattering approach calculate the spin current. Here, we show that tilting the Dirac cones can strongly change the transport properties by modifying the period of oscillation of the spin current. The spin conductance can be effectively tuned by the tilt with taking advantage of the modified interference condition. A pure spin current reversal also possible with a smooth variation of the tilting. We further study the spin current by the adiabatic precession of a doped ferromagnet on top of the material. It is shown that the spin-mixing conductance and hence the spin current can become zero by turning the tilt of the Dirac cone. Our findings provide an efficient way towards high controllability of spin transport by tuning the tilt of the ferromagnetic junction and can be very useful in the field of spintronics. The model also presents a simplified way to measure the tilt of Dirac cone of those materials.