Non-linear spin torque, pumping and cooling in superconductor/ferromagnet systems

Abstract

We study the effects of the coupling between magnetization dynamics and the electronic degrees of freedom in a heterostructure of a metallic nanomagnet with dynamic magnetization coupled with a superconductor containing a steady spin-splitting field. We predict how this system exhibits a non-linear spin torque, which can be driven either with a temperature difference or a voltage across the interface. We generalize this notion to arbitrary magnetization precession by deriving a Keldysh action for the interface, describing the coupled charge, heat and spin transport in the presence of a precessing magnetization. We characterize the effect of superconductivity on the precession damping and the anti-damping torques. We also predict the full non-linear characteristic of the Onsager counterparts of the torque, showing up via pumped charge and heat currents. For the latter, we predict a spin-pumping cooling effect, where the magnetization dynamics can cool either the nanomagnet or the superconductor.

9 pages, 5 figures

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Cited by in corpus (8)

• Large enhancement of spin pumping due to the surface bound states in normal metal/superconductor structures
• Magnon spin current induced by triplet Cooper pair supercurrents
• Anisotropic superconducting spin transport at magnetic interfaces
• Locking of magnetization and Josephson oscillations at ferromagnetic resonance in ${\phi }_0$ junction under external radiation
• Ferromagnetic resonance modulation in $d$-wave superconductor/ferromagnetic insulator bilayer systems
• Superconductivity provides a giant enhancement to the spin battery effect
• Topological charge, spin and heat transistor
• Anisotropic spin-current spectroscopy of ferromagnetic superconducting gap symmetries