Phenomenological modelling of first order phase transitions in magnetic systems

Abstract

First order phase transitions may occur in several magnetic systems, with two structural phases having different magnetic properties each and a structural transition between them. Here, a novel physics based phenomenological model of such systems is proposed, in which magnetization is represented by the volumetric amounts of ferromagnetism (described by extended Jiles-Atherton theory) and paramagnetism (described by the Curie-Weiss law) in respective phases. An identification procedure to extract material parameters from experimental data is proposed. The proposed phenomenological approach was successfully applied to magnetocaloric Gd5(SixGe 1-x)4 system and also has the potential to describe the behavior of Griffiths phase magnetic systems. © 2014 AIP Publishing LLC.