Geometrothermodynamic description of magnetic materials

We perform a statistical and geometrothermodynamic analysis of three different models of magnetic materials, namely, the translational free model, the spin model, and the mean-field model. First, we derive the fundamental equation for each model, which is then used as input to compute the metrics of the corresponding equilibrium spaces. Analyzing the corresponding geometrothermodynamic curvatures, we conclude that they can be used to describe thermodynamic interaction, stability conditions, and the phase transition structure of the modeled substances. In all the cases, we reproduce their well-known behavior close to the Curie temperature. Moreover, in the case of the model with spin, we found a curvature singularity, which corresponds to a novel transition, where a particular response function diverges, indicating the presence of a second-order phase transition, according to Ehrenfest classification.