Field-free magnetization switching in CoPt induced by noncollinear antiferromagnetic Mn3Ga

Abstract

The magnetic spin Hall effect (MSHE) may produce the out-of-plane spin current with $z$-direction polarization $({\mathbit{\ensuremath{\sigma}}}_{\mathbf{z}})$, thus allowing the field-free switching of perpendicular magnetization in ferromagnetic films. Here, we fabricate the epitaxial $L{1}_{1}\text{\ensuremath{-}}\mathrm{CoPt}/D{0}_{19}\text{\ensuremath{-}}\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ga}$ bilayers on MgO(111) substrates and characterize their magnetic and electrical transport properties. In the $L{1}_{1}\text{\ensuremath{-}}\mathrm{CoPt}/D{0}_{19}\text{\ensuremath{-}}\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ga}$ bilayers, we observe the spin-orbit torque switching of perpendicular magnetization under zero external field. The magnetization switching ratio and polarity are specifically related to the N\'eel vector direction of the antiferromagnetic ${\mathrm{Mn}}_{3}\mathrm{Ga}$ as well as the crystalline orientations which the pulse current is applied along. The field-free switching in the bilayers is attributed to the ${\mathbit{\ensuremath{\sigma}}}_{\mathbf{z}}$ spin current generated by the MSHE, which is driven by the reduced symmetry of ${\mathrm{Mn}}_{3}\mathrm{Ga}$ film with noncollinear spin structure.