Field-free spin-orbit torque switching by magnetic spin-Hall effect of non-collinear antiferromagnet Mn3Sn

Abstract

Antiferromagnetic (AFM) spintronics has attracted much attention because of its advantageous characteristics including ultrafast operation speed and high-density integration compared to the ferromagnet-based one. Among various AFM materials, a non-collinear AFM, Mn3Sn, is of particular interest due to its unique magnetic symmetry allowing magnetic spin Hall effect (MSHE). The MSHE can generate spin current carrying out-of-plane spin polarization and thereby switch the perpendicular magnetization without the help of an external magnetic field. In this paper, we first grow the Single and polycrystalline Mn3Sn films and analyzed their crystallinity, magnetic, and electric properties. Secondly, we fabricated the Mn3Sn/HM/FM tri-layer structure studied field-free SOT switching. In this structure we expected the out-of-plane spin current generated from the bottom Mn3Sn and exert torques on the perpendicularly magnetized Co layer. Interestingly, the SOT switching occurs even without an external magnetic field. This field-free switching behavior demonstrates that MSHE in Mn3Sn can generate a spin current with out-of-plane spin polarization. Also, we investigate the SOT switching varying the temperature, results were coincident with Mn3Sn’s phase transition temperature. This tendency also supports the origin of field-free switching as MSHE