Simulation of the magnetocaloric effect by means of theoretical models in Gd3Ni2 and Gd3CoNi systems

Abstract

In this work, using a scaling data method based on the mean-field theory (MFT), magnetization isotherms M (H, T) and magnetic entropy change − S M (T) curves have been simulated using MFT combined with the Bean-Rodbell model which verified the secondorder phase transition for Gd 3 Ni 2 and Gd 3 CoNi compounds. Under a low value of magnetic field H, M (T) and − S M (T) curves have been successfully simulated and some magnetocaloric properties have been evaluated using the phenomenological model.

Magnetic properties and magnetocaloric effect in Gd films and microwires

“…Solid lines (1) and (2) in Fig. 5 show approximations by corresponding functions suggested in [19,20].…”

“…To determine parameters of S M (T ) dependencies, it was necessary to select a model of approximation that made it possible to determine amplitude and width of S M (T ) peaks. We used two approaches developed within the theory of molecular field, where the phonon part of entropy is written in accordance with the Debye model [19] and the mean field model, where the exchange interaction is represented in the form of internal field added to the external field in the Brillouin function [20]. Solid lines (1) and (2) in Fig.…”

Study of the Magnetocaloric Effect by Means of Theoretical Models in La0.6Ca0.2Na0.2MnO3 Manganite Compound

“…The thermodynamics of the mean-field model presents an efficient method for estimating the MCE from experimental data of magnetic isotherms. The generalized formulation of the molecular interaction according to the mean-field leads to a scaling method [22][23][24], which allows the direct estimation of several magnetic parameters from experimental data. The Weiss molecular mean-field theory -4 -combined to the Bean-Rodbell model [25,26], also allow to adequately simulate the magnetic and magnetocaloric properties and to verify the type of FM-PM phase transition of the magnetic system.…”