Switching field interval of the sensitive magnetic layer in exchange-biased spin valves

The switching field interval, Delta H-s, of Ni-Fe-Co-based thin films and spin-valve layered structures, sputter-deposited on a Ta-buffer layer, was studied. The switching field interval is the field range in which the magnetization reversal of a ferromagnetic layer takes place. In thin films, Delta H-s is determined by the uniaxial anisotropy, induced by growth in a magnetic field. This anisotropy increases with the ferromagnetic layer thickness and saturates at a thickness of 10-25 nm. It also depends on the alloy composition as well as on the choice of the adjacent layers, In exchange-biased spin valves, an additional contribution to Delta H-s, was observed, which increases monotonically with increasing interlayer coupling. We explain this in terms of the effect on the magnetization reversal of the sensitive layer due to a simultaneous small, but temporary, magnetization rotation in the exchange-biased layer and lateral variations of the interlayer coupling. In addition, the effect of biquadratic coupling on Delta H-s is discussed. Finally, the thermal stability of Delta H-s is investigated. (C) 1997 American Institute of Physics.