Superfluid spin transport—dissipationless transport of spin—is theoretically studied in a ferromagnetic insulator with easy-plane anisotropy. We consider an open geometry where the spin current is injected into the ferromagnet from one side by a metallic reservoir with a nonequilibrium spin accumulation and ejected into another metallic reservoir located downstream. Spin transport is studied using a combination of magnetoelectric circuit theory, Landau-Lifshitz-Gilbert phenomenology, and microscopic linear-response theory. We discuss how spin superfluidity can be probed in a magnetically mediated negative electron-drag experiment.

• Received 1 November 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.227201