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

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.