Recent studies of non-equilibrium spin states in superconductors revealed a new rich physics originating from the coupling of spin both to charge and heat. I will discuss that superconducting wires subjected to a magnetic field can develop a peculiar thermospin effect which produces spin polarization in response to external heating or the injection of quasiparticles from the adjacent voltage-biased normal electrode [1]. The spin polarization and spin currents generated in such a way survive in the superconductor at length scales much larger than the spin relaxation length in the normal state in agreement with recent experiments. Detection of spin polarization can be done with the help of ferromagnetic electrodes which convert it to electric signals. Basic mechanisms of spin transport (spin Seebeck) and thermoelectric effects in spin-split superconductors are discussed in detail in our review papers [2,3]. I will also show how to utilize superconductors for spin-charge conversion in the presence of supercurrents [4] and use Abrikosov vortices for very efficient spin transport [5].

 

References:  

1. M. Silaev, P. Virtanen, F.S. Bergeret and T.T. Heikkilä, Phys. Rev. Lett. 114 (16), 167002 (2015).  

2. F.S. Bergeret, M. Silaev, P. Virtanen, T.T. Heikkilä, Rev. Mod. Phys 90 (4), 041001 (2018).

3. T.T. Heikkilä, M. Silaev, P. Virtanen, F.S. Bergeret, arXiv:1902.09297

4.  F. Aikebaier, M.A. Silaev, T.T. Heikkilä, , Phys. Rev. B 98, 024516 (2018).

5. A.Vargunin, M. Silaev,  Scientific Reports 9 5914 (2019)