Magnetization and giant magnetoresistance in melt-spun and annealed CuFeNi alloys

Magnetization and magnetoresistance (MR) of as-quenched and annealed (Tan &le 500°C) melt-spun Cu80Fe10Ni10 samples have been determined for temperatures 4.2 K an, magnetization and MR curves show no hysteresis for T ≥ 50 K, consistent with zero-field-cooled magnetization curves which present maxima around 50 K. Fitting the magnetization curves furnished average particle diameters in the range 1.8-3.1 nm. The particle size showed a minimum, and MR a maximum, as a function of annealing temperature. At 50 K, the largest value of MR (approx. 19%) was obtained for a sample annealed at 400°C for 2 h.