Effect of heat treatment and Co on the giant magnetoresistance of Fe-60 Cr-XCo alloy thin films

This article presents the giant magnetoresistance (GMR) effect and microstructure of Fe-60Cr-XCo ternary heterogeneous alloy films. After ion beam sputtering, the films are heat treated at a temperature within the miscibility gap. The separated phases and lattice images of the alpha(1) (Fe-Co rich phase) and alpha(2) (Cr rich phase) are further determined by high resolution transmission electron microscopy. In the granular alloy, the GMR effect is obtained by the interface scattering between the phases of alpha(1) and alpha(2). By isothermal aging at 550 degrees C for 80 min, the largest MR ratio of -62% appears for the film with the composition of Fe-60Cr-15Co at 77 K under a held of 14 kOe. For the same treatment, the MR ratios of Fe-60Cr-10Co and Fe-60Cr-20Co are -39% and -43%, respectively. The Co content and heat treatment condition in the alloy system obviously affect the MR ratio. (C) 1997 American Institute of Physics.