Thermal stability of IrMn and MnFe exchange-biased magnetic tunnel junctions

The thermal stability of exchange-biased magnetic tunnel junctions is explo red using near-edge x-ray absorption fine-structure spectroscopy. Structure s with Ir-Mn antiferromagnetic exchange bias layers are much more thermally stable than similar structures with Fe-Mn exchange bias layers. In both ca ses, diffusion of Mn from the antiferromagnetic layer through thin exchange -biased ferromagnetic layers to the tunnel barrier is observed at elevated temperatures. This observation explains the diminished magnetoresistance of these structures on annealing even though the resistance of the tunnel jun ctions is hardly changed. (C) 2000 American Institute of Physics. [S0003-69 51(00)04621-0].