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

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.