Materials that crystallize in diamond-related lattices, with Si and GaAs as their prime examples, are at the foundation of modern electronics. Simultaneously, inversion asymmetries in their crystal structure and relativistic spin–orbit coupling led to discoveries of non-equilibrium spin-polarization phenomena that are now extensively explored as an electrical means for manipulating magnetic moments in a variety of spintronic structures. Current research of these relativistic spin–orbit torques focuses primarily on magnetic transition-metal multilayers. The low-temperature diluted magnetic semiconductor (Ga, Mn)As, in which spin–orbit torques were initially discovered, has so far remained the only example showing the phenomenon among bulk non-centrosymmetric ferromagnets. Here we present a general framework, based on the complete set of crystallographic point groups, for identifying the potential presence and symmetry of spin–orbit torques in non-centrosymmetric crystals. Among the candidate room-temperature ferromagnets we chose to use NiMnSb, which is a member of the broad family of magnetic Heusler compounds. By performing all-electrical ferromagnetic resonance measurements in single-crystal epilayers of NiMnSb we detect room-temperature spin–orbit torques generated by effective fields of the expected symmetry and of a magnitude consistent with our ab initio calculations.
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C.C. acknowledges support from a Junior Research Fellowship at Gonville and Caius College. L.A. acknowledges support from the James B. Reynolds Scholarship at Dartmouth College. A.J.F. acknowledges support from a Hitachi Research Fellowship and a EU ERC Consolidator Grant No. 648613. F.G. acknowledges financial support from the University of Würzburg’s programme ‘Equal opportunities for women in research and teaching’. J.G. acknowledges support from SPIN+X SFB/TRR 173. J.G. and J.S. acknowledge support from the Alexander von Humboldt Foundation. L.Š. acknowledges support from the Grant Agency of the Charles University, No. 280815 and access to computing and storage facilities owned by parties and projects contributing to the National Grid Infrastructure MetaCentrum, provided under the programme ‘Projects of Large Infrastructure for Research, Development, and Innovations’ (LM2010005). J.Ž. and F.F. gratefully acknowledge computing time on the supercomputers JUQUEEN and JUROPA at Juelich Supercomputing Centre. T.J. acknowledges support from EU ERC Advanced Grant No. 268066, from the Ministry of Education of the Czech Republic Grant No. LM2011026, and from the Grant Agency of the Czech Republic Grant no. 14-37427.
The authors declare no competing financial interests.
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Ciccarelli, C., Anderson, L., Tshitoyan, V. et al. Room-temperature spin–orbit torque in NiMnSb. Nature Phys 12, 855–860 (2016). https://doi.org/10.1038/nphys3772
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