Spin–orbit torque (SOT)-driven deterministic control of the magnetic state of a ferromagnet with perpendicular magnetic anisotropy is key to next-generation spintronic applications including non-volatile, ultrafast and energy-efficient data-storage devices. However, field-free deterministic switching of perpendicular magnetization remains a challenge because it requires an out-of-plane antidamping torque, which is not allowed in conventional spin-source materials such as heavy metals and topological insulators due to the system’s symmetry. The exploitation of low-crystal symmetries in emergent quantum materials offers a unique approach to achieve SOTs with unconventional forms. Here we report an experimental realization of field-free deterministic magnetic switching of a perpendicularly polarized van der Waals magnet employing an out-of-plane antidamping SOT generated in layered WTe2, a quantum material with a low-symmetry crystal structure. Our numerical simulations suggest that the out-of-plane antidamping torque in WTe2 is essential to explain the observed magnetization switching.
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Funding for this research was provided primarily by the Center for Emergent Materials at The Ohio State University, a National Science Foundation (NSF) MRSEC through award number DMR-2011876. R.M. acknowledges NSF support through an AGEP-GRS supplement to award DMR-1809145. H.Z. and R.C. are supported by the Air Force Office of Scientific Research under grant FA9550-19-1-0307. J.Y. acknowledges support from the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. D.G.M. acknowledges support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant number GBMF9069. J.E.G. acknowledges financial support from the Center of Emergent Materials, an NSF MRSEC, under grant number DMR-2011876. D.W. gratefully acknowledges the financial support by the German Science Foundation DFG Research Fellowship (WE6480/1). Support for h-BN crystal growth from the Office of Naval Research from award N00014-20-1-2427 is appreciated. Electron microscopy was performed at the Center for Electron Microscopy and Analysis at The Ohio State University.
The authors declare no competing interests.
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Kao, IH., Muzzio, R., Zhang, H. et al. Deterministic switching of a perpendicularly polarized magnet using unconventional spin–orbit torques in WTe2. Nat. Mater. (2022). https://doi.org/10.1038/s41563-022-01275-5