Magnetic Equation of State Near the Critical Point of Ferrimagnets and Canted Ferromagnets

Abstract

The magnetic equation of state of single‐crystal ferrimagnets (YIG and MnFe₂O₄) and a canted ferromagnet (YFeO₃) were studied experimentally. Critical indices observed for the former two cubic ferrimagnets were γ=1.32 and 1.33±0.04, β=0.35±0.02, and δ=4.6±0.2, which are nearly the same as those of ferromagnets and satisfy the scaling law prediction γ=β(δ‐1). For the latter canted noncubic ferromagnet, a difference was found between the observations along different crystal axes. Along the z axis, we found that the magnetization, after subtracting the antiferromagnetic contribution from the observed magnetization, does follow the scaling law. The critical indices obtained were γ=1.9±0.2, β=0.47±0 05, and δ=5.1±0.5. Along the x axis, which is parallel to the spin axis of the antiferromagnet, complex dependence of the magnetization upon the applied magnetic field appears near the critical temperature. This phenomena can be explained by the field‐induced change of the spin axis from the x axis to the z axis near the Curie point, and is quite similar to the case of Iwahashi's induced canted ferromagnetism.