Giant dynamical electron-magnon coupling in metal-metal-ferromagnetic insulator heterostructure

TL;DR

This paper introduces a theoretical method to significantly enhance electron-magnon coupling at NM/FI interfaces by modifying the interfacial density of states, leading to a substantial increase in spin conductance.

Contribution

A novel theoretical formalism using non-equilibrium Green's functions to dynamically enhance electron-magnon coupling by manipulating interfacial DOS.

Findings

Spin conductance can be increased by nearly three orders of magnitude.

Effective electron-magnon coupling is proportional to the density of states at the interface.

The approach provides a new platform for controlling spin transport in heterostructures.

Abstract

Magnon-mediated spin transport across nonmagnetic metal (NM) and ferromagnetic insulator (FI) interface depends critically on electron-magnon coupling. We propose a novel route to enhance electron-magnon coupling dynamically from transport viewpoint. Using non-equilibrium Green's function a theoretical formalism for magnon-mediated spin current is developed. In the language of transport, the effective electron-magnon coupling at NM/FI interface is determined by self-energy of FI lead, which is proportional to density of states (DOS) at NM/FI interface due to nonlinear process of electron-magnon conversion. By modifying interfacial DOS, the spin conductance of 2D and 3D NM/FI systems can be increased by almost three orders of magnitude, setting up a new platform of manipulating dynamical electron-magnon coupling.