Magnetism and magnetoresistive properties in Fe_xCu_100-x alloys produced by mechanical alloying

Metallic granular Fe_xCu_100-x alloys with Fe concentration of x = 10-90 are prepared by mechanical alloying (MA). The alloy structure, magnetoresistance (MR), and magnetism have been investigated for as-milled and annealed samples. After milling for 50 h, the samples consist of a supersaturated solid solution of single fcc phase over the wide Fe concentration range x = 10-60. The magnetization of the as-milled samples deviates downward from a simple dilution law, decreases with decreasing x and vanishes at x ≃ 20. The maximum MR ratio, under 15 kOe at room temperature, is 1.2% for the sample with x = 28 annealed at 250°C for 1 h. The samples with x = 18-28 show reentrant spin-glass-like behavior. However, the samples with x greater than 25 show ferromagnetic behavior at room temperature.