Thermodynamics of metamagnetoelectric effect in multiferroics

Abstract

Abstract Magnetoelectric coupling in multiferroics gives rise to various properties such as metamagnetoelectric effect since external fields act. In this study, a general thermodynamic framework is developed to investigate metamagnetoelectric effects in multiferroic materials. The model used is a quasi-two dimensional frustrated spin chain controlled by a static electric field in y-direction and magnetic field in z-direction. The effects of metamagnetoelectric transitions on entropy, heat capacity and on the linear magnetoelectric coupling factor are assessed using Fermi-Dirac statistics of quantum gases and the Landau theory. The entropy behavior is shown to be similar to that of the magnetic susceptibility. In fact, while the magnetic susceptibility characterizes the variations of magnetization and accordingly emphasizes the ferroic transition points of this order, the intrinsic physics of these transition points highlights a muddle occurring due to a rearrangement of magnetic moments in the system, and this is accurately described in terms of entropy. The transition effects due to this rearrangement described in terms of entropy at the corresponding critical points show different loop to that of the heat capacity. The opposite loop showed by the heat capacity compared to the entropy is its weakening at the exact transition point in spite of its strengthening during the transition process. It is also recorded only a few ranges of the electric field which allows the effect provided. The temperature dependence of the magnetoelectric coupling highlights how it is continuously weakened by the increase of temperature, leading to a second order transition from the metamagnetoelectric state.