Giant field-like torque by the out-of-plane magnetic spin Hall effect in a topological antiferromagnet Mn3Sn*

   Spin-orbit torques (SOT) enable efficient electrical control of the magnetic state of ferromagnets and antiferromagnets. However, the conventional SOT via spin Hall effect (SHE) and Edelstein effect has severe limitation that only in-plane spins accumulate near the surface. Such a SOT is not suitable for controlling perpendicular magnetization, which would be more beneficial for realizing low-power-consumption memory devices. 

   Recently we focus on magnetic spin Hall effect (MSHE) in the topological Wely antiferromagnet Mn3Sn, in which the spin-polarization direction of current-induced spin accumulation changes its sign upon flipping the chiral antiferromagnetic order, i.e., the cluster magnetic octupole[1]. Notably, the magnetic order can be controlled by a small external magnetic field[2] or a spin-orbit torque[3]. Here, we will introduce our recent experimental results on the observation of a giant field-like torque via out-of-plane MSHE in the topological antiferromagnet Mn3Sn, whose direction and size can be tuned by changing the direction of order parameter[4]. Our findings provide a new route for efficient manipulation of magnetic states and realization of novel functionalities by utilizing topological Weyl antiferromagnets. This is the work in collaboration with H. Chen, T. Tomita, M. Ikhlas, T. Higo, A. MacDonald, S. Nakatsuji and Y. Otani.