Spin Hall effect and current induced magnetic switching in antiferromagnetic IrMn

Abstract

An antiferromagnetic metal (AFM) rich in spin-orbit coupling is a promising solid for the application of electrical current induced magnetic switching, because not only can it rely on its Spin Hall Effect (SHE) to generate spin current, it might also provide exchange coupling field to replace an external field required for coherent magnetic switching. In this work, we study the current induced magnetic switching by using the antiferromagnetic IrMn. The switching current density based on the spin Hall effect of IrMn is on the order of 1x106 A/cm2, which is comparable to the heavy metal systems with a large spin Hall angle. We observe an interesting switching behavior, in that a complete binary switching occurs under an applied field in the range of 2.0 to 8.0 mT, however, from zero field up to 2.0 mT, switching is continuous and incomplete. We attribute this observation to the distribution of exchange bias field and the mixture of internal and external field, which is attested by magneto-optical Kerr effect microscope. Our study sheds light on the SHE in AFM materials and their application in field-free switching such as in spin-logic and magnetic random-access memory devices.