Speaker: Yong Jiang
Place: Conference Room 502, Building Chao Kuang Piu, School of Materials Science & Engineering
Title: Spin transport in ferromagnet(antiferromagnet)/heavy metal bilayers
Time: 9th May, 2019, 14:30-15:30 p.m.
Inviter: Xiaoli Zhu
Abstract:
Spin Hall effect (SHE) that converts charge current into spin current in a heavy metal (HM) with strong spin-orbit coupling (SOC) has attracted much interest due to its practical use in technological applications. When a HM comes in contact with a ferromagnet (FM), the spin current that diffuses into the FM will modify the spin dependent transport properties such as anomalous Hall effect (AHE). On the other hand, the spin current will also exert torque on the magnetization, which is similar to spin transfer torque. The investigation and clarification of these intriguing issues are of fundamental importance for better understanding the underlying physics.
In this talk, we will briefly review the recent progress in our group on SOC, spin-orbit torque (SOT) and topological Hall effects in perpendicular magnetized FM (e.g. MnxGa)/HM structures. The sizeable SOT in the MnGa/IrMn films induced by the strong SHE of IrMn have been investigated. The IrMn layer also supplies an in-plane exchange bias field and enables nearly field-free magnetization reversal. In a antiferromagnet (AFM) Cr2O3/Heavy metal structure, a nearly 0.1% spin Hall magnetoresistance (SMR) ratio is achieved under a magnetic field of 9 T, which is larger than the reported value in SrMnO3/Pt structures. The antiferromagnetic Cr2O3/Ta bilayer shows negative SMR at low temperatures, which is attributed to the competition between the surface ferromagnetism and bulk antiferromagnetism of Cr2O3 (0001). We have also observed the existence of non-collinear magnetic structures and large topological Hall effect in MnGa/Pt and MnGa/Ta films induced by the strong interfacial DMI.
