The spin Hall effect (SHE) is usually observed as a bulk effect in high-symmetry crystals with substantial spin–orbit coupling (SOC), where the symmetric spin–orbit field imposes a widely encountered trade-off between spin Hall angle (θSH) and spin diffusion length (Lsf), and spin polarization, spin current and charge current are constrained to be mutually orthogonal. Here, we report a large θSH of 0.32 accompanied by a long Lsf of 2.2 μm at room temperature in a low-symmetry few-layered semimetal MoTe2, thus identifying it as an excellent candidate for simultaneous spin generation, transport and detection. In addition, we report that longitudinal spin current with out-of-plane polarization can be generated by both transverse and vertical charge current, due to the conventional and a newly observed planar SHE, respectively. Our study suggests that manipulation of crystalline symmetries and strong SOC opens access to new charge-spin interconversion configurations and spin–orbit torques for spintronic applications.
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The datasets generated by the present study are available from the corresponding author on request.
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We acknowledge S. Roche for insightful discussions. K.P.L. acknowledges the AME-IRG grant ‘Scalable Growth of Ultrathin Ferroelectric Materials for Memory Technologies’, no. A1938c0035, funded by the Agency for Science, Technology and Research, Singapore. P.S. thanks B. Özyilmaz for providing molecular-beam epitaxy slots and H. Chen for assistance in electron-beam lithography.
The authors declare no competing interests.
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Song, P., Hsu, C., Vignale, G. et al. Coexistence of large conventional and planar spin Hall effect with long spin diffusion length in a low-symmetry semimetal at room temperature. Nat. Mater. (2020). https://doi.org/10.1038/s41563-019-0600-4