Nonlinear longitudinal and transverse magnetoresistances due to current-induced magnon creation-annihilation processes

TL;DR

This paper shows that current-induced magnon creation and annihilation processes cause nonlinear magnetoresistance effects in magnetic bilayers, expanding understanding of charge-spin interactions.

Contribution

It introduces a new mechanism for nonlinear magnetoresistance driven by magnon dynamics, applicable to various magnetic systems.

Findings

Magnon creation-annihilation processes dominate second harmonic resistance.

Nonlinear magnetoresistance depends on current and magnetic field.

Results apply to both insulating and metallic magnetic layers.

Abstract

Charge-spin conversion phenomena such as the spin Hall effect allow for the excitation of magnons in a magnetic layer by passing an electric current in an adjacent nonmagnetic conductor. We demonstrate that this current-induced modification of the magnon density generates an additional nonlinear longitudinal and transverse magnetoresistance for every magnetoresistance that depends on the magnetization. Using harmonic measurements, we evidence that these magnon creation-annihilation magnetoresistances dominate the second harmonic longitudinal and transverse resistance of thin Y$_{3}$Fe$_{5}$O$_{12}$/Pt bilayers. Our results apply to both insulating and metallic magnetic layers, elucidating the dependence of the magnetoresistance on applied current and magnetic field for a broad variety of systems excited by spin currents.