Étude des propriétés magnétiques des superréseaux DyFe2/YFe2 par la méthode monte carlo

Abstract

The heterostructure consisted of a hard magnetic material and a soft magnetic material, allow the manufacture of artificial domain wall through an exchange coupling at the interface range. Typical examples of such compounds are superlattices DyFe2/YFe2 consist of alternating layers of hard ferrimagnetic materials DyFe2 and soft ferrimagnetic layers YFe2. This thesis is evoted to study by numerical Monte Carlo simulation the process of magnetization reversal of superlattices DyFe2/YFe2. Previous experimental studies on inter-metallic superlattices, show a wide variety of results that tell us about the magnetic behavior of these superlattices for different temperatures and for a set thicknesses for the hard magnetic layer (DyFe2) relative to the soft magnetic layer (YFe2). For a better understanding of magnetic behavior, we undertook a model of Heisenberg spins vector allowing any rotation of the spins in space, the model is suitable for studying non-collinear magnetic structures, such as superlattices DyFe2/YFe2. The magnetic energy of these superlattices is the result of three contributions: the exchange energy, magnetocrystalline anisotropy and the Zeeman effect in the presence of an applied magnetic field. The objective of this work is to study the effect of the relative thickness and the influence of temperature on the magnetic properties of DyFe2/YFe2 superlattices. In these systems, it is generally agreed that the magnetization reversal process takes place by the development of walls in the soft magnetic material (YFe2), followed by irreversible magnetization reversal of the hard magnetic material (DyFe2). The simulation of hysteresis loops allowed us to get a good qualitative agreement with experimental results.