EXCHANGE-ANISOTROPY IN COUPLED FILMS OF NI81FE19 WITH NIO AND COXNI1-XO

Shifted hysteresis loops were used to investigate exchange anisotropy in 500 angstrom CoxNi1-xO/300 angstrom Ni81Fe19 polycrystalline bilayer couples. Bilayers of Ni81Fe19 with NiO have a room-temperature exchange field, H(e), of 30 Oe in the as-deposited state. A maximum in the exchange field at room temperature was observed near x=0.4, indicating an optimal alloying of the properties of the high anisotropy CoO and the high Neel temperature NiO. The blocking temperatures of the exchange couples vary linearly with x, suggesting a linear dependence of the oxide Neel temperature with x.