Critical phenomena of amorphous Nd4(Fe0.75Cr0.25)77.5B18.5 alloys

Abstract The magnetic behavior of amorphous Nd 4 (Fe 0.75 Cr 0.25 ) 77.5 B 18.5 alloys was investigated in the critical region. The Curie temperature T C and critical exponents β , γ and δ are found to be 141 K, 0.45±0.02, 1.64±0.08 and 4.66±0.10, respectively. The data are fitted to a magnetic equation of state characteristic of a second-order phase transition over a rather wide range of temperatures both above and below T C . It is noted that the values of the exponents are in disagreement with those derived for a three-dimensional Heisenberg ferromagnet and show an enhancement. This anomalous critical behavior may originate from magnetic inhomogeneity.