Grain boundary mediated oxidation and interlayer dipolar coupling in a magnetic tunnel junction structure

We present a study detailing changes in the layers of a magnetic tunnel junction that has been overoxidized to explore the impact of unwanted oxidation. From the evidence of grain boundary diffusion, we conclude that the microstructure plays an important role in determining the impact of the oxidation process. Layer-dependent switching measurements show that the change in the tunneling magnetoresistance was solely due to modified dipolar coupling after field annealing into the exchange biased state. This was confirmed by scattering measurements, which show clearly that the preanneal and postanneal interfacial structure remains unchanged.