A UNIVERSAL SCALING PROPERTY OF THE GIANT MAGNETORESISTANCE IN NANOCRYSTALLIZED CU-CO MELT-SPUN RIBBONS

We present the field and temperature dependencies of the magnetoresist ance in melt spun Cu86Co14 and Cu92Co8 ribbons nanocrystallized by ann ealing them at higher temperatures. It is found that the giant magneto resistance, GMR, values measured at 5K, 77K, and room temperature scal e as a function of B/(T+ theta) in the regime where the nanocrystals a re superparamagnetic. Furthermore, by taking into account the evolutio n of the magnetic properties of the nanocrystals with annealing, all t he GMR data are found to be collapsible to a universal function, with the Langevin variable mB/(T+theta), where m is a scaling factor depend ent on the magnetic property of the annealed state.