Direct detection of spin Hall effect in an antiferromagnetic material*

The spin Hall effect is one of the key phenomena in spintronics since it enables efficient electrical manipulation of magnetization. The figure of merit of this effect is the spin Hall angle given by the ratio of spin to charge currents. Antiferromagnetic materials have already demonstrated high spin Hall angles as detected using indirect electrical measurements [1,2]. Here, we report the direct measurement of the interfacial spin accumulation induced by the spin Hall effect in antiferromagnetic PtMn thin films using magnetic circular dichroism (XMCD)- photoemission electron microscopy (PEEM). We show that the XMCD has opposite sign at the L₃ edge of Mn for opposite charge current directions and scales linearly with current density. We quantitatively determine the current-induced spin accumulation at the PtMn interface as 8.8×10⁻¹² μ_BA⁻¹cm² per atom averaged over the probing depth which translates into a positive spin Hall angle of 0.25 (±0.1). Our results show the direct, spatially resolved, interface free and element-selective measurement of the SHE in a CuAu-I-type antiferromagnetic material by means of X-ray microscopy.

[1] W. Zhang, M. B. Jungfleisch, W. Jiang et al., Phys. Rev. Lett. 113 196602 (2014)

[2] Y. Ou, S. Shi, D. C. Ralph et al., Phys. Rev. B 93 220405(R) (2016)