Spin currents, spin torques, and the concept of spin superfluidity

Abstract

In magnets with non-collinear spin configuration the expectation value of the conventionally defined spin current operator contains a contribution which renormalizes an external magnetic field and hence affects only the precessional motion of the spin polarization. This term, which has been named angular spin current by Sun and Xie [Phys. Rev B 72, 245305 (2005)], does not describe the translational motion of magnetic moments. We give a prescription how to separate these two types of spin transport and show that the translational movement of the spin is always polarized along the direction of the local magnetization. We also show that at vanishing temperature the classical magnetic order parameter in magnetic insulators cannot carry a translational spin current, and elucidate how this affects the interpretation of spin supercurrents.

8 pages, 3 figures

References in corpus (9)

• On A Proper Definition of Spin Current
• Superfluid spin transport through antiferromagnetic insulators
• Spin Josephson effect in ferromagnet/ferromagnet tunnel junctions
• Non-Local Transport Mediated by Spin-Supercurrents
• Theory of spin current in chiral helimagnet
• Theory of conserved spin current and its application to two dimensional hole gas
• What are spin currents in Heisenberg magnets?
• Spin superfluidity and spin-orbit gauge symmetry fixing
• Conservation and persistence of spin currents and their relation to the Lieb-Schulz-Mattis twist operators

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• Designing Rashba-Dresselhaus effect in magnetic insulators
• All-electrical Magnon Transport Experiments in Magnetically Ordered Insulators
• Bose-Einstein Condensation of Nonequilibrium Magnons in Confined Systems
• Skyrmion quantum spin Hall effect
• Topological nature of the proper spin current and the spin-Hall torque
• Spin-orbit torques and their associated effective fields from gigahertz to terahertz
• Monopole Josephson Effects in a Dirac Spin Liquid
• Superuniversal transport near a $(2+1)$-dimensional quantum critical point
• Transport properties of spin superfluids: comparing easy-plane ferro- and antiferromagnets
• Theory of generalized Josephson effects
• Spin and charge transport in topological nodal-line semimetals
• Ferroelectricity in a magnon Bose-Einstein condensate: Nonreciprocal superfluidity, exceptional points, and Majorana bosons
• Berry Phase origin of the planar spin Hall effect