Effects of spin injection on the anisotropic magnetoresistance in antiferromagnetic Sr₂IrO₄

The emerging field of antiferromagnetic (AFM) spintronics aims at the active control and manipulation of AFM moments to be used in future spintronic devices. Crucial to its success is a rigorous method to detect and monitor the orientation of AFM moments. Very large anisotropic magnetoresistance (MR) observed in antiferromagnetic iridates [1] is touted to provide just that. Here we study the effects of spin injection on the magnetoresistance in AFM Mott insulator Sr₂IrO₄. To generate and inject a pure spin current into a single-crystal Sr₂IrO₄ we exploit the spin Hall effect in a thin Pt layer deposited directly onto the crystal. The magnetoresistance effect in Sr₂IrO₄ was measured with and without the spin injection from Pt. We observed a significant increase of MR with the spin current. The increase may be tentatively associated with a spin-transfer torque generated by the current on local magnetic moments in Sr₂IrO₄. [1] C. Wang et al., Phys. Rev. X 3, 041034 (2014).