Spin transport and giant thermomagnetics effects in ferromagnetic/superconductor structures
Par Mihail Silaev, KTH Royal institute of technology, Stockholm, Sweden
Mercredi 23 Mars, 14h, Salle des séminaires, 3ème étage, Batiment A4
Recent studies of non-equilibrium spin states in superconductors revealed a rich physics originating from the interplay between magnetism and superconductivity. Several experiments [1,2] observed a giant spin accumulation available in superconducting wires generated by the current injected from normal electrodes. The striking phenomenon of an extra-large spin relaxation length and time in superconductors with strong Zeeman splitting has been reported. In this talk I will suggest a theoretical explanation of these experiments. It will be shown that a non-equilibrium spin polarization can be generated from heat injection due to the peculiar thermomagnetic effect in superconducting wires . Various possibilities of generating long-living non-equilibrium spin states and manipulating spin-polarized currents in superconductors will be discussed. I will demonstrate that superconductivity can either strongly enhance or suppress the coherent spin rotation , depending on the type of spin relaxation mechanism being dominated either by spin-orbit coupling or spin-flip scattering at impurities.
 C.H.L. Quay, D. Chevallier, C. Bena, M. Aprili, Nature Phys. 9, 84 (2013).
 F. Hübler, M.J. Wolf, D. Beckmann, H. v. Löhneysen, Phys. Rev. Lett. 109, 207001 (2012).
 M. Silaev, P. Virtanen, F. S. Bergeret, and T. T. Heikkilä, Long-Range Spin Accumulation from Heat Injection in Mesoscopic Superconductors with Zeeman Splitting, Phys. Rev. Lett. 114, 167002 (2015).
 M. Silaev, P. Virtanen, T. T. Heikkilä, and F. S. Bergeret, Spin Hanle effect in mesoscopic superconductors, Phys. Rev. B 91, 024506 (2015).