Exchange coupling and GMR properties in ion beam sputtered hematite spin-valves

We have succeeded in fabricating hematite (/spl alpha/-Fe/sub 2/O/sub 3/) antiferromagnetic (AF) thin films by the ion beam sputtering method, which give unidirectional anisotropy to the adjacent ferromagnetic layer. Its exchange bias energy (J/sub ex/) is 0.03 erg/cm/sup 2/, and blocking temperature (T/sub b/) is 250/spl deg/C. Spin-valve films with the hematite AF layer were also fabricated. They exhibit GMR property with unidirectional anisotropy of the pinned layer. Spin- valve films of which magnetic layers consist of only NiFe exhibit relatively low MR ratio and poor thermal stability. However, the spin-valve using Co as the pinned layer and the free layer at the Cu interface exhibits MR ratio of more than 6% and excellent thermal stability.