Spin Seebeck effect in a polar antiferromagnet $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$

TL;DR

This study investigates the spin Seebeck effect in the polar antiferromagnet $ ext{Cu}_2 ext{V}_2 ext{O}_7$, revealing that magnon dynamics primarily govern the effect's dependence on magnetic field and temperature.

Contribution

It demonstrates the spin Seebeck effect in a polar antiferromagnet and links its behavior to magnon lifetime changes, expanding understanding beyond ferromagnetic systems.

Findings

Spin Seebeck voltages are observed below the antiferromagnetic transition temperature.

Magnetic field dependence is similar to that in MnF$_2$|Pt bilayers.

Magnon lifetime variations explain the temperature and magnetic field dependence.

Abstract

We have studied the longitudinal spin Seebeck effect in a polar antiferromagnet $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$ in contact with a Pt film. Below the antiferromagnetic transition temperature of $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$, spin Seebeck voltages whose magnetic field dependence is similar to that reported in antiferromagnetic MnF$_{2}$$\mid$Pt bilayers are observed. Though a small weak-ferromagnetic moment appears owing to the Dzyaloshinskii-Moriya interaction in $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$, the magnetic field dependence of spin Seebeck voltages is found to be irrelevant to the weak ferromagnetic moments. The dependences of the spin Seebeck voltages on magnetic fields and temperature are analyzed by a magnon spin current theory. The numerical calculation of spin Seebeck voltages using magnetic parameters of $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$ determined by previous neutron scattering studies reveals that the magnetic-field and temperature dependences of the spin Seebeck voltages for $\alpha$-Cu$_{2}$V$_{2}$O$_{7}$$\mid$Pt are governed by the changes in magnon lifetimes with magnetic fields and temperature.