Observation of spin splitting torque in a collinear antiferromagnet RuO2

TL;DR

This paper provides experimental evidence of spin splitting torque in collinear antiferromagnet RuO2, demonstrating its potential as a new spin source for spintronics by correlating spin current and polarization with crystal and magnetic orientations.

Contribution

The study experimentally confirms the existence of spin splitting torque in RuO2, a novel spin torque mechanism predicted theoretically, expanding the understanding of spin torques in antiferromagnets.

Findings

Spin current direction correlates with crystal orientation.

Spin polarization depends on the N9el vector.

Evidence supports the predicted spin splitting torque in RuO2.

Abstract

Current-induced spin torques provide efficient data writing approaches for magnetic memories. Recently, the spin splitting torque (SST) was theoretically predicted (R. Gonz\'alez-Hern\'andez et al. Phys. Rev. Lett. 126, 127701 (2021)), which combines advantages of conventional spin transfer torque (STT) and spin-orbit torque (SOT) as well as enables controllable spin polarization. Here we provide the experimental evidence of SST in collinear antiferromagnet RuO2 films. The spin current direction is found to be correlated to the crystal orientation of RuO2 and the spin polarization direction is dependent on (parallel to) the N\'eel vector. These features are quite characteristic for the predicted SST. Our finding not only present a new member for the spin torques besides traditional STT and SOT, but also proposes a promising spin source RuO2 for spintronics.