Anomalous Critical Behavior of Amorphous Fe100-xZrx Ferromagnets (x=8 and 10)

The critical behavior of magnetic phase transition in amorphous Fe 92 Zr 8 and Fe 90 Zr 10 ferromagnets has been studied by static magnetization measurement. The magnetization data taken in the critical region yield the following values for the critical exponents, respectively: β=0.620 ±0.003, γ=1.92 ±0.02, δ=5.82 ±0.06 for Fe 92 Zr 8 ; and β=0.560 ±0.003, γ=1.87 ±0.02, δ=4.84 ±0.06 for Fe 90 Zr 10 . These values deviate substantially from those derived for a three dimmensional homogeneous Heisenberg ferromagnet. The results, together with other anomalous magnetic phenomena, have been discussed as originating from an extremely wide distribution of exchange integrals. In particular, it has been suggested that the spin-glass like behavior can be ascribed to the thermally activated magnetization process of the cluster-spin glass.