Magnon Pumping by a Time-Dependent Transverse Magnetic Field in Ferromagnetic Insulators

TL;DR

This paper theoretically investigates how a time-dependent transverse magnetic field can generate magnon currents in ferromagnetic insulators, highlighting a resonance effect that enhances magnon pumping.

Contribution

It introduces a theoretical framework for magnon pumping driven by a transverse magnetic field, emphasizing the resonance structure of the magnon source term.

Findings

Magnon current generation is linked to the magnon source term in the spin continuity equation.

The magnon source term exhibits a resonance structure as a function of the field's angular frequency.

Resonance can be exploited to enhance magnon pumping effects.

Abstract

The magnon pumping effect in ferromagnetic insulators under an external time-dependent transverse magnetic field is theoretically studied. Generation of a magnon current is discussed by calculating the magnon source term in the spin continuity equation. This term represents the non-conservation of magnons arising from an applied transverse magnetic field. The magnon source term has a resonance structure as a function of the angular frequency of the transverse field, and this fact is useful to enhance the pumping effect.