Improvement in magnetoresistance of very thin permalloy films by post-annealing

We prepared Ni₈₀Fe₂₀ films by the sputter-beam method and investigated their magnetotransport properties. The very thin film of 200 Å exhibited a high magnetoresistance of 3.5% after an appropriate post-annealing treatment. The improvement is due to the decrease of zero-field resistivity resulting from remarkable grain growth in the films. Taking into account diffusive electron scattering at the film surface, the magnetoresistance value is thought to be very close to that of the bulk.