Influence of annealing on thermal stability of IrMn-based magnetic tunnel juctions

Abstract

The magnetic tunnel junction with a structure of IrMn/CoFe/AlOx/CoFe is deposited by magnetron sputtering and annealed at different temperatures in a magnetic field of parallel to the orienting field. Vibrating sample magnetometer is used to record the magnetic hysteresis loop at room temperature, and scanning probe microscope is used to record the interface morphology. The influence of annealing on thermal stability of the magnetic tunnel junction is investigated by holding the film in its negative saturation field. After annealing, the exchange bias increases due to the enhancement of unidirectional anisotropy of antiferromagnetic layer. The recoil loop of the pinned ferromagnetic layer shifts towards the positive field, and the exchange bias field decreases monotonically, with the film held in a negative saturation field, whereas annealing reduces the reduction speed of Hex.