Analysis of the Magnetic Susceptibility as a Function of Temperature for the α, β and γ Phases of Oxygen

Abstract

We analyse the magnetic susceptibility χ as a function of temperature (zero pressure) for the transitions of α- β, β- γ and γ-liquid below and above the transition temperatures for oxygen according to a power-law formula. The observed data are used from the literature, and the values of the critical exponents for the magnetic susceptibility are deduced close to the phase transitions in oxygen. Our exponent values give a logarithmic singularity for the magnetic susceptibility χ in the vicinity of Tc as in the specific heat at constant magnetic field, CM. Our exponent values (γ≃ 0) are not in agreement with the predictions for the magnetic susceptibility (γ≃ 1) of some theoretical models, which undergo essentially a second order transition. Our analysis gives an indication that the α- β transition is a weak first order (less discontinuity in χ), whereas the β- γ and γ-liquid transitions are closer to a first order (more discontinuous behaviour than the α- β transition in oxygen). The effect of the magnetic interactions on the α- β, β- γ and γ-liquid transitions in oxygen is explained.