Controllable Spin Current in van der Waals Ferromagnet Fe3GeTe2

TL;DR

This paper theoretically investigates how the spin current in van der Waals ferromagnet Fe3GeTe2 can be controlled through magnetization and symmetry, revealing nonlinear behaviors and multiple spin polarization states relevant for spintronic devices.

Contribution

It demonstrates the control of spin current magnitude and polarization in Fe3GeTe2 by manipulating symmetry and magnetization, introducing a new method for spin-orbit torque applications.

Findings

Spin current exhibits nonlinear dependence on magnetization.

Simultaneous emergence of in-plane and out-of-plane spin polarization.

Bilayer FGT can achieve arbitrary spin polarization.

Abstract

The control of spin current is pivotal for spintronic applications, especially for spin-orbit torque devices. Spin Hall effect (SHE) is a prevalent method to generate spin current. However, it is difficult to manipulate its spin polarization in nonmagnet. Recently, the discovery of spin current in ferromagnet offers opportunity to realize the manipulation. In the present work, the spin current in van der Waals ferromagnet Fe3GeTe2 (FGT) with varying magnetization is theoretically investigated. It has been observed that the spin current in FGT presents the nonlinear behavior with respect to magnetization. The in-plane and out-of-plane spin polarization emerges simultaneously, and the bilayer FGT can even exhibit arbitrary spin polarization thanks to the reduced symmetry. More intriguingly, the correlation between anomalous Hall effect (AHE) and spin anomalous Hall effect (SAHE) has been interpreted from the aspect of Berry curvature. This work illustrates that the interplay of symmetry and magnetism can effectively control the magnitude and spin polarization of the spin current, providing a practical method to realize exotic spin-orbit torques.