極清浄雰囲気中で作製したAg-Co薄膜の構造とGMR効果 : Cu-Co薄膜との比較  [in Japanese] Microstructure and Giant Magnetoresistance of Ag-Co Films Fabricated by Means of an Extremely Clean Sputtering Process  [in Japanese]

The influence of impurities in the sputtering stmosphere on the microstructure and giant magnetoresistance (GMR) of Ag_<100-x>Co_x(x=0-62at%) thin films was investigated. Ag-Co films were prepared on quartz substrates at room temperature, varying the purity of the sputtering atomosphere by changing the base pressure, with 10^<-11> Torr for an extremely clean process (XC-process) and 10^<-7> Torr for a lower-grade process (LG-process). The correlation between the microstructure and the GMR of Ag-Co films after annealing is discussed. It was found that (1) the precipitation of Co particles progressed in the as-deposited films, and the degree of supersaturation of the matrix phase in the LG-processed films was higher than that in the XC-processed films; (2) the size of the Co particles precipitated in the as-deposited LG-processed films was larger than that in the XC-processed films, and resulted in a higer MR ratio of the asdeposited LG-processed films than that of the XC-processed ones under a maximum applied field of 14kOe; (3) the magnitude of the MR ratio in the XC-processed films after annealing above 300℃ was larger than that in the LG-processed ones, apparently because of the homogeneity of the Co particles of the precipitate.