Giant thermoelectric effect in Al2O3 magnetic tunnel junctions

TL;DR

This paper demonstrates a giant magnetothermoelectric effect in Al2O3 magnetic tunnel junctions, showing significant thermovoltage and tunable Seebeck coefficient, advancing spin caloritronics and thermoelectric spintronics.

Contribution

It reports the first observation of a giant magnetothermoelectric effect in Al2O3 magnetic tunnel junctions with tunable thermoelectric properties.

Findings

Thermovoltage reaches 1 mV in the junctions.

Magneto-thermovoltage ratio is comparable to tunnel magnetoresistance.

Seebeck coefficient can be controlled by magnetic orientation.

Abstract

Thermoelectric effects in magnetic nanostructures and the so-called spin caloritronics are attracting much interest. Indeed it provides a new way to control and manipulate spin currents which are key elements of spin-based electronics. Here we report on giant magnetothermoelectric effect in Al2O3 magnetic tunnel junctions. The thermovoltage in this geometry can reach 1 mV. Moreover a magneto-thermovoltage effect could be measured with ratio similar to the tunnel magnetoresistance ratio. The Seebeck coefficient can then be tuned by changing the relative magnetization orientation of the two magnetic layers in the tunnel junction. Therefore our experiments extend the range of spintronic devices application to thermoelectricity and provide a crucial piece of information for understanding the physics of thermal spin transport.