Magnetic properties and giant magnetoresistance of magnetic granular Co10 Cu90 alloys obtained by direct‐current joule heating

The direct-current (de) joule heating technique was exploited to fabricate giant magnetoresistance (GEAR) Co10Cu90 granular alloys. The Co cluster precipitation process was investigated by calorimetric and x-ray 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 samples show relatively high GMR in comparison with furnace-annealed samples. Based on the phenomenological GMR model, we assumed that it is a consequence of smaller Co particles formed in de joule-heated samples. (C) 1995 American Institute of Physics