title: Two-Fluid Theory for Spin Superfluidity in Magnetic Insulators.
abstract: We investigate coupled spin and heat transport in easy-plane magnetic insulators. These materials display a continuous phase transition between normal and condensate states that is controlled by an external magnetic field. Using hydrodynamic equations supplemented by Gross-Pitaevski phenomenology and magnetoelectric circuit theory, we derive a two-fluid model to describe the dynamics of thermal and condensed magnons, and the appropriate boundary conditions in a hybrid normal-metal-magnetic-insulator-normal-metal heterostructure. We discuss how the emergent spin superfluidity can be experimentally probed via a spin Seebeck effect measurement.
authors.affiliation: Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Flebus
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Bender
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Tserkovnyak
authors.affiliation: Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
authors.forename: R A
authors.initials: RA
authors.lastname: Duine