MAGNETIC-PROPERTIES AND GIANT MAGNETORESISTANCE OF MAGNETIC GRANULAR CO10CU90 ALLOYS OBTAINED BY DIRECT-CURRENT JOULE HEATING

The direct-current (de) joule heating technique was exploited to fabri cate giant magnetoresistance (GEAR) Co10Cu90 granular alloys. The Co c luster precipitation process was investigated by calorimetric and x-ra y diffraction measurements. At T=10 K, the largest MR change of 25.0% has been observed for the melt-spun Co10Cu90 ribbon annealed at I=5 A. The magnetoresistance scales approximately as the inverse Co particle size. At room temperature, it was found that the de joule-heated samp les show relatively high GMR in comparison with furnace-annealed sampl es. Based on the phenomenological GMR model, we assumed that it is a c onsequence of smaller Co particles formed in de joule-heated samples. (C) 1995 American Institute of Physics.