Nonlinear Susceptibility of Ni near the Curie Temperature

Abstract

The ac linear (χ₀) and nonlinear (χ₂) susceptibilities of a ferromagnetic Ni have been studied near the Curie temperature, to clarify the feature of the magnetic phase transition. The first observation for the critical behavior of χ₂ in a pure ferromagnetic system has been made at low frequency measurement. The observed χ₂ at higher frequencies is affected extremely by the contribution of the eddy currents. From analysis of the frequency dependence of χ₀ and χ₂, the method of eddy-current correction for χ₂ is found. Analysis of the critical behavior of χ₀ and χ₂ yields the critical exponents γ =1.333± 0.008 and γ ₂=4.69± 0.30.