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arXiv · 1805.00730

Spin-pumping-induced inverse spin-Hall effect in Nb/Ni80Fe20 bilayers and its strong decay across the superconducting transition temperature

K. -R. Jeon·C. Ciccarelli·H. Kurebayashi·J. Wunderlich·L. F. Cohen·S. Komori·J. W. A. Robinson·M. G. Blamire
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Abstract

We quantify the spin Hall angle {\theta}SH and spin diffusion length lsd of Nb from inverse spin-Hall effect (iSHE) measurements in Nb/Ni80Fe20 bilayers under ferromagnetic resonance. By varying the Nb thickness tNb and comparing to a Ni80Fe20/Pt reference sample, room temperature values of {\theta}SH and lsd for Nb are estimated to be approximately -0.001 and 30 nm, respectively. We also investigate the iSHE as a function of temperature T for different tNb. Above the superconducting transition temperature Tc of Nb, a clear tNb-dependent T evolution of the iSHE is observed whereas below Tc, the iSHE voltage drops rapidly and is below the sensitivity of our measurement setup at a lower T. This suggests the strong decay of the quasiparticle (QP) charge-imbalance relaxation length across Tc, as supported by an additional investigation of the iSHE in a different sample geometry along with model calculation. Our finding suggests careful consideration should be made when developing superconductor spin-Hall devices that intend to utilize QP-mediated spin-to-charge interconversion.

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K. -R. Jeon, C. Ciccarelli, H. Kurebayashi, J. Wunderlich, L. F. Cohen, S. Komori, J. W. A. Robinson, M. G. Blamire. 2018-05-02. Spin-pumping-induced inverse spin-Hall effect in Nb/Ni80Fe20 bilayers and its strong decay across the superconducting transition temperature. https://arxiv.org/abs/1805.00730

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