Spin manipulation in nanoscale superconductors

Abstract

The interplay of superconductivity and magnetism in nanoscale structures has attracted considerable attention in recent years due to the exciting new physics created by the competition of these antagonistic ordering phenomena, and the prospect of exploiting this competition for superconducting spintronics devices. While much of the attention is focused on spin-polarized supercurrents created by the triplet proximity effect, the recent discovery of long range quasiparticle spin transport in high-field superconductors has rekindled interest in spin-dependent nonequilibrium properties of superconductors. In this review, the experimental situation on nonequilibrium spin injection into superconductors is discussed, and open questions and possible future directions of the field are outlined.

Spin-current coherence peak in superconductor/magnet junctions

“…We measured inverse spin Hall effects induced by spin injection from a ferrimagnetic insulator Y3Fe5O12 into a superconductor NbN using longitudinal spin Seebeck effects. In the vicinity of the superconducting transition temperature of the NbN, a large enhancement of the spin Seebeck voltage is observed, whose sign is opposite to that for the vortex Nernst effect, but is consistent with a calculation for a coherence peak effect in the superconductor NbN.Superconducting spintronics is an emerging research field which explores new spintronic functions by combining superconducting and magnetic orders [1][2][3][4][5]. One of the key ingredients in the superconducting spintronics is generation of spin-polarized carriers in superconductors [6].…”

Charge transport through spin-polarized tunnel junction between two spin-split superconductors

“…More recently, non-equilibrium properties of superconductors with a spin-split density of states have attracted a renewed attention [12][13][14][15][16][17][18] . In such systems, two additional spin-dependent modes appear and couple to the widely studied non-equilibrium energy and charge modes 16,19 .…”

Enhanced spin pumping into superconductors provides evidence for superconducting pure spin currents

“…Direct spin transport studies in SCs [7][8][9][10] have traditionally involved quasiparticle (QP) injection at bias voltages around the superconducting gap energy. A number of exotic properties have been observed: enhanced spin relaxation time [11][12][13] , spin and charge decoupling 9,10 and a giant spin-orbit interaction 14 .…”