Comparison of the magneto-Peltier and magneto-Seebeck effects in magnetic tunnel junctions

TL;DR

This study investigates the magneto-Peltier effect in magnetic tunnel junctions, demonstrating its reciprocal relationship with the magneto-Seebeck effect, and estimates its magnitude, paving the way for programmable thermoelectric devices.

Contribution

It is the first experimental study of the magneto-Peltier effect in MTJs, showing its linear and nonlinear behaviors and confirming Onsager reciprocity with magneto-Seebeck measurements.

Findings

Magneto-Peltier signal scales linearly with current at small bias.

Enhanced magneto-Peltier effect observed at large bias due to Joule heating.

Estimated magneto-Peltier coefficient of 13.4 mV in the linear regime.

Abstract

Understanding heat generation and transport processes in a magnetic tunnel junction (MTJ) is a significant step towards improving its application in current memory devices. Recent work has experimentally demonstrated the magneto-Seebeck effect in MTJs, where the Seebeck coefficient of the junction varies as the magnetic configuration changes from a parallel (P) to an anti-parallel (AP) configuration. Here we report the study on its as-yet-unexplored reciprocal effect, the magneto-Peltier effect, where the heat flow carried by the tunneling electrons is altered by changing the magnetic configuration of the MTJ. The magneto-Peltier signal that reflects the change in the temperature difference across the junction between the P and AP configurations scales linearly with the applied current in the small bias but is greatly enhanced in the large bias regime, due to higher-order Joule heating mechanisms. By carefully extracting the linear response which reflects the magneto-Peltier effect, and comparing it with the magneto-Seebeck measurements performed on the same device, we observe results consistent with Onsager reciprocity. We estimate a magneto-Peltier coefficient of 13.4 mV in the linear regime using a three-dimensional thermoelectric model. Our result opens up the possibility of programmable thermoelectric devices based on the Peltier effect in MTJs.