Abstract
We demonstrate spin injection into superconducting Nb by employing a spin absorption technique in lateral spin valve structures. Spin currents flowing in a nonmagnetic Cu channel are preferably absorbed into Nb due to its strong spin-orbit interaction, the amount of which dramatically changes below or above the superconducting critical temperature (). The charge imbalance effect observed in the interface ensures that superconducting Nb absorbs pure spin currents even below . Our analyses based on the density of states calculated using the Usadel equation can well reproduce the experimental results, implying that the strong spin-orbit interaction of Nb is still effective for the spin absorption even below . Most importantly, our method allows us to determine the intrinsic spin relaxation time in the superconducting Nb, which reaches more than 4 times greater than that in the normal state.
- Received 8 October 2013
DOI:https://doi.org/10.1103/PhysRevLett.112.036602
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