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Abstract

Abstract---In CoCrTa/Cr double-layered thin films deposited on Si single crystalline substrates, the effect of Ti addition in the Cr underlayer on magnetic properties and microstructural properties of the films before and after heat-treatment was investigated. The CoCrTa/Cr films turned to be nonmagnetic after heattreatment at 550°C. On the other hand, the coercivity of CoCrTa/CrTi films was greatly increased by the heat-treatment at 550°C. X-ray diffraction patterns indicated that Cr silicide was formed for the film with Cr underlayer and not formed for the film with Cr 94 Ti 6 underlayer after the heat-treatment at 550°C. The grain size of the film with the Cr underlayer was decreased. However, the grains seemed to be Cr silicide, CrSi z , from the result of the XRD patterns. In the case of the CoCrTa/Cr 94 Ti 6 , the distribution of the grain size was narrowed and the region around the grains seemed to be amorphous-like structure after the heaf-treatment at 550°C. It was shown with Auger Electron Spectroscopic depth profiles that, in the film with the Cr underlayer, the Si diffusion into the magnetic upperlayer occurred after the heat-treatment at 550°C, whereas with the CrTi underlayer, no diffusion of Si occurred and Cr concentration in magnetic upperlayer was increased in the films. Furthermore, the ~M value of CoCrTa/Cr 94 Ti 6 film shifted from a positive to a negative region with the increase in the heat-treatment temperature. After the heat-treatment at 550°C, the surface morphology of the film with the Cr underlayer became rougher by precipitate, whereas those of the film with the Cr 94 Ti 6 underlayer was kept smooth. These results imply that the increase in coercivity of the CoCrTa/CrTi film after the heat-treatment is attributed to the suppression of the Si diffusion into the magnetic upperlayer and to the enhancement of the magnetic isolation between the grains in the upperlayer by the Cr diffusion.