Interfacial Spin and Heat Transfer between Metals and Magnetic Insulators

TL;DR

This paper investigates how thermal magnons influence spin and heat transfer at metal-insulator ferromagnet interfaces, revealing temperature-dependent effects on spin currents and magnetic dynamics.

Contribution

It introduces a theoretical framework to calculate spin and energy currents considering thermal magnons and spin misalignment at the interface.

Findings

Thermal magnons contribute significantly to spin currents.

Spin currents depend on temperature differences and spin misalignment.

Magnetic torque varies with temperature due to magnonic effects.

Abstract

We study the role of thermal magnons in the spin and heat transport across a normal-metal/insulating-ferromagnet interface, which is beyond an elastic electronic spin transfer. Using an interfacial exchange Hamiltonian, which couples spins of itinerant and localized orbitals, we calculate spin and energy currents for an arbitrary interfacial temperature difference and misalignment of spin accumulation in the normal metal relative to the ferromagnetic order. The magnonic contribution to spin current leads to a temperature-dependent torque on the magnetic order parameter; reciprocally, the coherent precession of the magnetization pumps spin current into the normal metal, the magnitude of which is affected by the presence of thermal magnons.