Seebeck Effect in Magnetic Tunnel Junctions

TL;DR

This paper reports the experimental observation of the magneto-Seebeck effect in magnetic tunnel junctions, where magnetic configuration changes influence the thermoelectric voltage, revealing a new aspect of spin-caloritronic phenomena.

Contribution

The study demonstrates the first experimental realization of the magneto-Seebeck effect in magnetic tunnel junctions, showing controllable voltage changes based on magnetic states.

Findings

Observed 8.8% magneto-Seebeck effect.

Voltage change of about -8.7 μV/K between magnetic states.

Effect magnitude aligns with theoretical predictions.

Abstract

Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, i.e., the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel junction. In that respect, it is the analog to the tunneling magnetoresistance. The Seebeck coefficients in parallel and antiparallel configuration are in the order of the voltages known from the charge-Seebeck effect. The size and sign of the effect can be controlled by the composition of the electrodes' atomic layers adjacent to the barrier and the temperature. Experimentally, we realized 8.8 % magneto-Seebeck effect, which results from a voltage change of about -8.7 {\mu}V/K from the antiparallel to the parallel direction close to the predicted value of -12.1 {\mu}V/K.