Abstract
We demonstrate an anomalous spin-orbit torque induced by the broken magnetic symmetry in the antiferromagnet IrMn. We study the magnetic structure of three phases of IrMn thin films using neutron diffraction technique. The magnetic mirror symmetry M′ is broken laterally in both L10-IrMn and L12-IrMn3 but not γ-IrMn3. We observe an out-of-plane dampinglike spin-orbit torque in both L10-IrMn/permalloy and L12-IrMn3/permalloy bilayers but not in γ-IrMn3/permalloy. This is consistent with both the symmetry analysis on the effects of a broken M′ on spin-orbit torque and the theoretical predictions of the spin Hall effect and the Rashba-Edelstein effect. In addition, the measured spin-orbit torque efficiencies are 0.61 ± 0.01, 1.01 ± 0.03, and 0.80 ± 0.01 for the L10,L12, and γphases, respectively. Our work highlights the critical roles of the magnetic asymmetry in spin-orbit torque generation.
| Original language | English |
|---|---|
| Article number | 184403 |
| Journal | Physical Review B |
| Volume | 101 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 1 2020 |
Funding
The Laboratory is a National Research Infrastructure under the National Research Foundation (NRF) Singapore. J.C. is a member of Singapore Spintronics Consortium (SG-SPIN). This research is supported by the Singapore Ministry of Education MOE2018-T2-2-043, AMEIRG18-0022, A*STAR IAF-ICP 11801E0036, and MOE Tier1 R-284-000-195-114. This project was partially supported by the National Key Research and Development Program of China (Title: Nonvolatile and programmable spin logics based on magnetic heterostructures; Grant No. 2017YFA0206200) for the device micro-fabrications. We would like to acknowledge Singapore Synchrotron Light Source (SSLS) for providing the facility necessary for conducting the research. P.Y. was supported by SSLS via NUS Core Support C-380-003-003-001. A portion of this research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, US-DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. B.Y. acknowledges the financial support by a research grant from the Benoziyo Endowment Fund for the Advancement of Science. Y.L. and T.H. received support from UT-Batelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.