Magnon scattering in the transport coefficients of CoFe alloys

TL;DR

This study investigates how magnon scattering influences the transport properties of CoFe alloys by measuring resistivity, thermopower, and thermal conductivity across different compositions, revealing significant magnon effects especially in thermopower.

Contribution

It provides new insights into the role of magnon scattering in transport coefficients and tracks the evolution of Mott and magnon drag contributions across alloy compositions.

Findings

Magnon effects are significant in thermopower but weak in resistivity and thermal conductivity.

The evolution of Mott and magnon drag contributions is mapped between pure Fe and pure Co.

A sign change in magnon drag contribution is observed.

Abstract

Resistivity $\rho$, thermopower ${\cal S}$, and thermal conductivity $\kappa$ were measured simultaneously on a set of CoFe alloy films. Variation of the Co-content $x_\mathrm{Co}$ allows for a systematic tuning of the Fermi level through the band structure, and the study of the interplay between electronic and magnetic contributions to the transport coefficients. While band structure and magnon effects in $\rho$ and $\kappa$ are rather weak, they turn out to be very significant in ${\cal S}$. The evolution of Mott and magnon drag contributions to ${\cal S}$ is traced between the two limiting cases of pure Fe and pure Co. In addition, we find an interesting sign change of the magnon drag.