Giant magnetoresistance in Co-Cu granular alloy films and nanowires prepared by pulsed-electrodeposition

Granular CoxCu1-x alloy films and nanowires were prepared by pulsed-electro deposition. The alloy composition was changed by controlling pulse-width of the current pulse with fixed off-time of the deposition. Alloy films were formed onto evaporated Cu films grown on glass plates. The face-centered cu bic lattice parameter was found to decrease with increasing Co content in t he films in the composition range investigated (0.17 less than or equal to x less than or equal to 0.66), and the second phase, probably by hexagonal close-packed phase, appeared at x greater than or equal to 0.42. The crysta llite size of the as-deposited condition calculated using the XRD data and the Scherrer's formula ranged between 10-30 nm, The magnetoresistance (MR) was found to become larger after annealing at an appropriate temperature be tween 400-600 degrees C, The maximum value of the MR ratio of about 4% was Observed at the composition around x = 0.2. Magnetic hysteresis curves were measured for Co0.31Cu0.69 and compared with those reported for sputtered a lloy films. Granular nanowires prepared into the pores of the alumite plate were also examined and reported briefly. (C) 1999 Elsevier Science Ltd. Al l rights reserved.