Coupled spin and heat transport in superconductor hybrid structures

Abstract

Superconductor–ferromagnet nanoscale hybrid structures have attracted considerable theoretical and experimental efforts, both due to the fundamental question of the competition of superconductivity and magnetism, and possible applications in superconducting spintronics and quantum information processing. Most of the attention has recently been focussed on magnetic Josephson junctions and the triplet proximity effect, and several chapters in this book are devoted to this topic. In addition to triplet Cooper pairs, superconductor–ferromagnet hybrid structures feature spin-polarized quasiparticle transport. Quasiparticles are exclusively responsible for heat transport in superconductors, since the Cooper pairs carry no entropy. In this chapter, we discuss recent developments in the investigation of coupled quasiparticle spin and heat transport in nanoscale superconductors with a spin splitting of the density of states. The coupling of spin and heat transport leads to very slow spin relaxation and giant thermoelectric effects, which could lead to interesting applications in thermometry or microrefrigeration.