Spin-mediated charge-to-heat current conversion phenomena in ferromagnetic binary alloys

TL;DR

This study investigates spin-mediated charge-to-heat current conversion effects, specifically the AEE and AMPE, in various ferromagnetic binary alloys at room temperature, revealing material-dependent behaviors and potential for improved thermoelectric applications.

Contribution

It provides a systematic analysis of the AEE and AMPE in ferromagnetic alloys, highlighting material-specific thermoelectric properties and their relation to magnetic and transport characteristics.

Findings

Ni$_{95}$Pt$_{5}$ shows the largest AMPE with 12% anisotropy.

Ni$_{75}$Pt$_{25}$ and Ni$_{50}$Fe$_{50}$ exhibit the largest AEE signals.

Strong material dependence of thermoelectric conversion coefficients observed.

Abstract

Spin-mediated charge-to-heat current conversion phenomena, i.e., the anomalous Ettingshausen effect (AEE) and the anisotropic magneto-Peltier effect (AMPE), have been investigated in various ferromagnetic Ni-Fe, Ni-Pt, Ni-Pd, and Fe-Pt binary alloys at room temperature. When a charge current is applied to a ferromagnetic conductor, the AMPE modulates the Peltier coefficient depending on the angle between the directions of the charge current and magnetization, while the AEE generates a heat current in the direction perpendicular to both the charge current and magnetization. We observed the strong material dependence of the thermoelectric conversion coefficients and figures of merit of these phenomena. Among the ferromagnetic alloys used in this study, Ni$_{95}$Pt$_{5}$ exhibits the largest AMPE of which the anisotropy of the Peltier coefficient is $\sim 12\%$. In contrast, the magnitude of the AEE signals is moderate in Ni$_{95}$Pt$_{5}$ but largest in Ni$_{75}$Pt$_{25}$ and Ni$_{50}$Fe$_{50}$. We discuss these behaviors by exploring the relations between these charge-to-heat current conversion phenomena and other transport as well as magnetic properties. This systematic study will provide a clue for clarifying the mechanisms of the AMPE and AEE and for enhancing the thermoelectric conversion efficiency of these phenomena.