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

We have succeeded in fabricating of hematite (alpha-Fe2O3) antiferromagnetic (AF) thin films by the ion beam sputtering method, which give unidirectional anisotoropy to the adjacent ferromagnetic layer. Its exchange bias energy (J(ex)) is 0.03 erg/cm(2), and blocking temperature (T-b) is 250 degrees C. Spin-valve films with the hematite AF layer were also fabricated. They exhibit GMR property with unidirectional anisotoropy 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.