Large spin–orbit torques (SOTs) generated by topological materials and heavy metals interfaced with ferromagnets are promising for next-generation magnetic memory and logic devices. SOTs generated from y spin originating from spin Hall and Edelstein effects can realize field-free magnetization switching only when the magnetization and spin are collinear. Here we circumvent the above limitation by utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate. We observe conventional SOT due to y spin, and out-of-plane and in-plane anti-damping-like torques originated from z spin and x spin, respectively, in MnPd3/CoFeB heterostructures. Notably, we have demonstrated complete field-free switching of perpendicular cobalt via out-of-plane anti-damping-like SOT. Density functional theory calculations show that the observed unconventional torques are due to the low symmetry of the (114)-oriented MnPd3 films. Altogether our results provide a path toward realization of a practical spin channel in ultrafast magnetic memory and logic devices.
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Field-free spin-orbit torque switching assisted by in-plane unconventional spin torque in ultrathin [Pt/Co]N
Nature Communications Open Access 04 July 2023
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This research was supported in part by ASCENT, one of six centres in JUMP, a Semiconductor Research Corporation (SRC) programme sponsored by DARPA. The authors thank the NSF Center for Energy Efficient Electronics Science (E3S) and TSMC for financial support. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF)/Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under award ECCS-1542152. The research at the University of Nebraska-Lincoln was supported by the National Science Foundation through EPSCoR RII Track-1 Program under award OIA-2044049. P.Q. acknowledges support from the National Research Council Research Associateship Program. S.E. and M.B.V. acknowledge funding from NSF award DMR-1905909, and assistance from Randy Dumas at Quantum Design with VSM measurements. A.H. and W.-G.W. acknowledge funding from NSF award DMR-1905783. F.X. acknowledges funding from TSMC under the JDP programme with award number SPO135237. Y.-L.H acknowledges the financial support from Center for Semiconductor Technology Research from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by MOE in Taiwan, and the National Science and Technology Council, Taiwan, under grants NSTC 110-2634-F-009-027 and NSTC 111-2112-M-A49-012-MY3. M.M. was supported by JSPS KAKENHI (18KK0414 and 20H02184), Heiwa Nakajima Foundation, PMAC for Science Research Promotion Fund and JST-FOREST (JPMJFR202G). Certain commercial equipment and instruments are identified in this paper to foster understanding. Any mention of commercial products is for information only; it does not imply recommendation or endorsement by the National Institute of Standards and Technology. The authors thank C. H. Diaz, P. Li and J. Jamtgaard for fruitful discussions.
The authors declare no competing interests.
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DC, M., Shao, DF., Hou, V.DH. et al. Observation of anti-damping spin–orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3. Nat. Mater. 22, 591–598 (2023). https://doi.org/10.1038/s41563-023-01522-3
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Field-free spin-orbit torque switching assisted by in-plane unconventional spin torque in ultrathin [Pt/Co]N
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