Seminar by Prof. Ilya Vekhter, Louisiana State University

Title: Spin-caloritronics of unconventional superconductors

Abstract: The term spin-caloritronics was coined to describe interaction of quasiparticle spins with heat currents. In this talk I focus on this interplay in unconventional, and specifically topological and non-unitary, superconductors. Interplay between superconductivity and magnetism has generated significant interest in exotic superconductors as a platform for superconducting spintronics.

A major obstacle is the paucity of reliable tests for materials that are time-reversal preserving yet exhibit topological and non-unitary superconducting orders that enable spin-polarized transport. I argue that the spin currents driven by thermal gradients provide a sensitive probe of the nature of the pairing in such superconductors.

I show that nonvanishing impurity-driven spin-Nernst effect can be used to identify helical Cooper pairs, while finite superconducting spin-Seebeck and spin-Nernst signals together can be used to pinpoint non-unitary superconductors. I  provide an estimate of the magnitude of this effect in candidate materials to show that such measurements are within the range of experiments in near future, and discuss open questions currently under investigation.

Speaker: Prof. Ilya Vekhter Department of Physics and Astronomy,  Louisiana State University, Baton Rouge, LA 70803-4001