Systematic Investigation of Anisotropic Magneto-Peltier Effect and Anomalous Ettingshausen Effect in Ni Thin Films

TL;DR

This study systematically investigates the anisotropic magneto-Peltier and anomalous Ettingshausen effects in Ni thin films, revealing their dependence on substrate thermal conductivity and confirming their symmetry properties through thermography.

Contribution

It introduces a method to isolate pure AMPE and AEE contributions in ferromagnetic thin films and demonstrates their behavior with different substrates and magnetic field angles.

Findings

AMPE temperature modulation varies with cos 2θ_H pattern.

AEE temperature modulation varies with cos θ_H pattern.

AMPE decreases with higher substrate thermal conductivity.

Abstract

The anisotropic magneto-Peltier effect (AMPE) and anomalous Ettingshausen effect (AEE) have been investigated in U-shaped Ni thin films of varying thickness and substrate by means of the lock-in thermography (LIT) method. We have established a procedure to extract pure AMPE and AEE contributions, separated from other thermoelectric effects, for ferromagnetic thin films. The measurements of the magnetic-field-angle $\theta_{\rm H}$ dependence of the LIT images clearly show that the temperature modulation induced by the AMPE (AEE) in the Ni films varies with the $\cos 2\theta_{\rm H}$ ($\cos \theta_{\rm H}$) pattern, confirming the symmetry of the AMPE (AEE). The systematic LIT measurements using various substrates show that the AMPE-induced temperature modulation decreases with the increase in thermal conductivity of the substrates, whereas the AEE-induced temperature modulation is almost independent of the thermal conductivity, indicating that the heat loss into the substrates plays an important role in determining the magnitude of the AMPE-induced temperature modulation in thin films. Our experimental results were reproduced by numerical calculations based on a two-dimensional finite element method. These findings provide a platform for investigating the AMPE and AEE in thin film devices.