Spin currents in superconductors

TL;DR

Experiments on rotating superconductors suggest the presence of macroscopic spin currents, which are predicted by the hole superconductivity model and are essential in a proposed electrodynamic theory, arising via an intrinsic spin Hall effect.

Contribution

The paper links experimental evidence and theoretical models to propose the existence of macroscopic spin currents in all superconductors, supported by a new electrodynamic framework.

Findings

Evidence from rotating superconductor experiments supports spin currents.

Hole superconductivity model predicts universal spin currents.

Spin currents originate from an intrinsic spin Hall effect during superconducting transition.

Abstract

It is argued that experiments on rotating superconductors provide evidence for the existence of macroscopic spin currents in superconductors in the absence of applied external fields. Furthermore it is shown that the model of hole superconductivity predicts the existence of such currents in all superconductors. In addition it is pointed out that spin currents are required within a related macroscopic (London-like) electrodynamic description of superconductors recently proposed. The spin current arises through an intrinsic spin Hall effect when negative charge is expelled from the interior of the metal upon the transition to the superconducting state.