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arXiv · 1612.01927

Spin-Hall Torques Generated by Rare-Earth (Lanthanide) Thin Films

Neal Reynolds·Priyamvada Jadaun·John T. Heron·Colin L. Jermain·Jonathan Gibbons·Robyn Collette·R. A. Buhrman·D. G. Schlom·D. C. Ralph
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Abstract

We report an initial experimental survey of spin-Hall torques generated by the rare-earth metals Gd, Dy, Ho, and Lu, along with comparisons to first-principles calculations of their spin Hall conductivities. Using spin torque ferromagnetic resonance (ST-FMR) measurements and DC-biased ST-FMR, we estimate lower bounds for the spin-Hall torque ratio, $ξ_{SH}$, of $\approx$ 0.04 for Gd, $\approx$ 0.05 for Dy, $\approx$ 0.14 for Ho, and $\approx$ 0.014 for Lu. The variations among these elements are qualitatively consistent with results from first principles (density functional theory, DFT, in the local density approximation with a Hubbard-U correction). The DFT calculations indicate that the spin Hall conductivity is enhanced by the presence of the partially-filled $f$ orbitals in Dy and Ho, which suggests a strategy to further strengthen the contribution of the $f$ orbitals to the spin Hall effect by shifting the electron chemical potential.

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Neal Reynolds, Priyamvada Jadaun, John T. Heron, Colin L. Jermain, Jonathan Gibbons, Robyn Collette, R. A. Buhrman, D. G. Schlom, D. C. Ralph. 2016-12-06. Spin-Hall Torques Generated by Rare-Earth (Lanthanide) Thin Films. https://doi.org/10.1103/physrevb.95.064412

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