Magnetization and giant magnetoresistance in melt-spun and annealed CuFeNialloys

Magnetization and magnetoresistance (MR) of as-quenched and annealed (T-an less than or equal to 500 degrees C) melt-spun Cu80Fe10Ni10 samples have be en determined for temperatures 4.2 K < T < 300 K, in magnetic fields up to 70 kOe. For all T-an magnetization and MR curves show no hysteresis for T g reater than or equal to 50 K, consistent with zero-field-cooled magnetizati on curves which present maxima around 50 K. Fitting the magnetization curve s furnished average particle diameters in the range 1.8 - 3.1 nm. The parti cle size showed a minimum, and MR a maximum, as a function of annealing tem perature. At 50 K, the largest value of MR (similar to 19%) was obtained fo r a sample annealed at 400 degrees C for 2 h. (C) 1999 Elsevier Science B.V . All rights reserved.