The thermal decay in the IrMn-based spin valve

Abstract

Thermal decay of the top spin valve with a structure of // Seed Ta (5nm) / Co75Fe25 (5nm) / Cu (2.5nm) / Co75Fe25 (5nm) /Ir20Mn80 (12nm) / Cap Ta (8nm) deposited at room temperature by magnetron sputtering has been investigated by means of holding the film in its negative saturation field at various temperatures. Vibrating sample magnetometer has been used to record the magnetic hysteresis loops at room temperature. The recoil loop of the pinned ferromagnetic layer shifts towards the positive field and the exchange bias field (Hex) decreases monotonously while holding the film in a negative saturation field. The decrease of Hex while holding the film in a negative saturation field indicates a thermally decay process. Due to the exchange coupling at the antiferromagnetic/ferromagnetic interface, the antiferromagnetic moments reverse by thermal activation over an energy barrier distribution, which may change in some way as the temperature increases.