The spin splitting torque (SST) was theoretically proposed to combine advantages of conventional spin transfer torque (STT) and spin-orbit torque (SOT) as well as enable controllable spin current (1). This talk presents experimental evidences of SST and the inverse effect in collinear antiferromagnet RuO2 films. First, according to spin torque ferromagnetic resonance (ST-FMR) measurements of RuO2 films, we exhibit that spin current direction is correlated to the crystal orientation of RuO2 and spin polarization direction is dependent on (parallel to) the Néel vector, indicating the existence of SST in RuO2 (2). Second, based on spin Seebeck effect and THz emission measurements, we demonstrate that inverse SST effect can convert spin current polarized along Néel vector into charge current, which manifests as Néel vector-dependent spin Seebeck voltage signals and THz emission signal (3). These findings not only presents a new member for the spin torques besides traditional STT and SOT, but also proposes RuO2 for both promising spin source and spin sink for spintronics.
(1) R. González-Hernández, et al., Phys. Rev. Lett. 126, 127701 (2021).
(2) H. Bai, C. Song, et al. accpeted by Phys. Rev. Lett. 128, 197202 (2022).
(3) H. Bai, C. Song, et al. In preparation.