Tunneling magneto thermocurrent in CoFeB/MgO/CoFeB based magnetic tunnel junctions

TL;DR

This paper investigates the magnetization-dependent thermoelectric effects in CoFeB/MgO/CoFeB magnetic tunnel junctions, revealing significant changes in thermopower and thermocurrent with magnetization orientation, explained by Onsager relations.

Contribution

It presents the first detailed study of tunneling magneto thermocurrent in CoFeB/MgO/CoFeB MTJs, contrasting previous AlO-based systems.

Findings

Thermopower increases by up to 55% when switching magnetization

Thermocurrent drops by 45% with magnetization reversal

Results align with Onsager relations considering tunneling magnetoresistance

Abstract

We study the tunneling magneto thermopower and tunneling magneto thermocurrent of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJ). The devices show a clear change of the thermoelectric properties upon reversal of the magnetisation of the CoFeB layers from parallel to the antiparallel orientation. When switching from parallel to antiparallel the thermopower increases by up to 55% where as the thermocurrent drops by 45%. These observations can be well explained by the Onsager relations taking into account the tunneling magneto resistance of the MTJ. These findings contrast previous studies on AlO based MTJ systems, revealing tunneling magneto thermo power but no tunneling magneto thermocurrent.