MAGNETIC-ORDERING IN FE-SUBSTITUTED AUCR ALLOYS NEAR PERCOLATION CONCENTRATION

We report DC susceptibility measurements on Au-82(Cr1-xFex)(18) alloys (0 less than or equal to x less than or equal to 0.4) in the temperat ure range 5 K to 300 K. For x = 0, an inhomogeneous antiferromagnetic state is observed which also exhibits magnetic irreversibility in the field-cooled condition similar to that of spin glasses. The temperatur e dependence of the susceptibility in the x = 0.2 alloy shows a field- dependent transition while in the x = 0.4 alloy a double transition is observed, of which the lower part is field dependent. An attempt to f it the field dependence of this temperature to a power law yields an e xponent of value 0.52 +/- 0.05. The observed behaviour appears to be c ontrolled by the distribution of magnetic clusters in the alloys.