Thermal stability of magnetic tunneling junctions with MgO barriers for high temperature spintronics

Thermal stability of MgO-based magnetic tunnel junctions has been investigated from room temperature up to 500°C, in both the memory and sensor configurations. Junctions showed magnetoresistances of over 200% at room temperature and over 100% at 300°C. Below 375°C, the resistance of the parallel state remains constant, while the antiparallel state resistance linearly decreases with temperature. Above that, a rapid increase in the resistance of both states was observed, along with an irreversible loss of magnetoresistance. Junctions in the sensor configuration exhibited a constant sensitivity of 1.0%/Oe at temperatures up to 300°C before getting degraded.