THE EVOLUTION OF SPIN-GLASS STATE IN AUFE REENTRANT SPIN-GLASS BY CR SUBSTITUTION - A MAGNETORESISTANCE STUDY

A detailed study of magnetoresistance (DELTArho/rho) has been carried out on a series of Au82(Fe1-xCrx)18 alloys with 0 less-than-or-equal-t o x less-than-or-equal-to 0.6 in the temperature range of 4.2-300 K an d in magnetic fields up to 45 kOe. The AC susceptibility measurements carried out earlier showed that the system undergoes a transition from a re-entrant spin-glass phase for Fe-rich alloys to spin-glass phase for Cr-rich alloys. The magnetoresistance measurements show a progress ive increase of magnetic disorder below the re-entrant spin glass tran sition. For 0.15 less-than-or-equal-to x less-than-or-equal-to 0.4, DE LTArho/rho shows a behaviour similar to that of cluster glasses. For x = 0.6, DELTArho/rho exhibits a spin-glass-type behaviour. The magneti c field (H) dependence of DELTArho/rho shows that there exists a uniqu e power-law dependence of H2/3 below the Curie temperature in Cr-conta ining re-entrant spin glasses.