Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 84: Focus Session: Nanoscopic Superconducting Heterostructures
TT 84.5: Topical Talk
Thursday, March 19, 2015, 11:45–12:15, H 0104
Spin Injection and Relaxation in a Mesoscopic Superconductor — •Marco Aprili1, Charis Quay1, Denis Chevalier1, Clement Dutreix1, Cristina Bena2, and Christoph Strunk3 — 1Laboratoire de Physique des Solides, CNRS UMR-8502, Bât. 510, Université Paris-Sud, 91405 Orsay Cedex, France — 2Institut de Physique Théorique, CEA/Saclay, Orme des Merisiers, 91190 Gif-sur-Yvette Cedex, France — 3Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
Injecting spin-polarized electrons or holes into a superconductor and removing Cooper pairs creates both spin and charge imbalances. We have investigated the relaxation of the out-of-equilibrium magnetization induced by spin injection. First, we measured the spin and charge relaxation times (tS and tQ) by creating a dynamic equilibrium between continuous injection and relaxation, this leads to constant-in-time spin and charge accumulation proportional to their respective relaxation times. Using a mesoscopic “absolute” spin-valve, we obtained tS and tQ by probing the difference on the chemical potential between quasiparticles and Cooper pairs. We observed that spin (charge) accumulation dominates at low (high) injection current. This artificially generates spin-charge separation as theoretically first predicted by Kivelson and Rokhsar. Second, we directly measured the spin relaxation time in the frequency space and found tS = 1−10 ns consistent with results from constant current injection. Finally, we measured the spin coherence time of the out-of-equilibrium quasi-particles by performing an electron spin resonance experiment.