Magnetostatic critical point phenomena of ErIGa garnet

Abstract

The magnetostatic critical point phenomena of an ErIGa garnet, Er3(Fe0.8Ga0.2)5O12, single crystal sphere were investigated by a computer controlled vibrating sample magnetometer. Subtracting the induced large spin paramagnetic moment of Er3+ from the measured values, allowed the Fe-sublattice magnetization Msub(H,T) to be extracted. Msub data were used to analyze the critical phenomena by eliminating the low field data to avoid the effect of the magnetic inhomogeneity. The spontaneous magnetization and the zero-field susceptibility were obtained from the Arrot plot. The critical temperature and critical indices were obtained to be Tc=463.64 K, β=0.48±0.03, γ=1.1±0.1, and δ=3.1±0.1. These results agree well with the predicted values from the molecular field theory. The plot of the critical equation of states ψ(H,M) showed the same function as that found for Fe. Thus, Msub(H,T) was shown to satisfy the second-order phase transition based on the molecular field theory.