Spin–orbit torque switching of the antiferromagnetic state in polycrystalline Mn3Sn/Cu/heavy metal heterostructures

The spin-orbit torque (SOT) using spin Hall effect has led to significant innovations in spintronics. Recently, SOT switching of an antiferromagnetic state of the Weyl semimetal Mn3Sn is realized by passing electrical current into Mn3Sn/heavy metal heterostructures. Here we demonstrate the SOT switching of Hall resistance in polycrystalline Mn3Sn/Pt, Mn3Sn/W and Mn3Sn/Cu/Pt, Mn3Sn/Cu/W heterostructures. Our experiments indicate that the sign of the spin Hall angle of heavy metals determines the direction of magnetic switching in both devices with and without Cu insertion layer, being consistent with the SOT mechanism. In Mn3Sn/Pt and Mn3Sn/W bilayer devices, the critical current density of electrical switching is ∼1011A/m2 in heavy metals. In addition, we find that the volume fraction of the switched Mn3Sn domain is nearly the same in devices with and without Cu layer, which indicates that the spin current generated from the spin Hall effect of Pt or W contributes dominantly to the SOT compared to possible interfacial effects at Mn3Sn/heavy metal interface.