Cr migration in CoNiTa/Cr films by annealing

CoNiTa/Cr double-layered films for longitudinal magnetic recording media have been prepared by using the facing targets sputtering apparatus. Substrate heating and postannealing were performed in order to increase the coercive force H/sub c/. While the as-deposited film at the substrate temperature T/sub s/ of 400 degrees C had H/sub c/ of 780 Oe, the films deposited at T/sub s/ of room temperature, exposed to atmosphere, and annealed at 400 degrees C, had H/sub c/ as high as 1700 Oe. It has been found that the same amount of Cr atoms migrated from the underlayer to the magnetic layer and the vicinity of the film surface. Consequently, such a large increase of H/sub c/ seemed to be caused by isolation of magnetic grains by Cr atoms in their boundaries.<
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