Etude des propriétés électroniques et magnétiques de Troilite FeS et les propriétés magnétocaloriques de l’alliage MnFe4Si3 : méthodes Monte Carlo et ab initio.

Abstract

In this thesis, we studied the magnetic properties of the FeS and MnFe4Si3 compounds which are characterized by the very high Curie temperature. First, for the compound FeS we calculated the interaction couplings and described the electronic properties by intervening the approximation of the functional density theory (DFT), thus by the implementation of the Metropolis code within the framework of the model from Ising we deduce the phase diagrams and the magnetic properties of FeS. We also studied the magnetocaloric effect and the magnetic properties in the MnFe4Si3 alloy by Monte Carlo simulation method (MCS) after having calculated the interaction couplings carried out by experimental studies. This simulation shows the performances and the functionalities of these compounds in various fields. Then, we carried out a study by MCS to investigate the magnetic frustration in a square lattice due to the competition of the ferromagnetic and antiferromagnetic coupling so we identify the different possible states and precisely the frustrated state, so we studied the magnetic properties and the hysteresis cycles for each state.