Skip to Main content Skip to Navigation
Theses

Contribution à l'étude de l'ordre de spins, de charge et effets structuraux dans le modèle de double-échange : chaîne linéaire, échelles de spins et manganites.

Abstract : The goal of this thesis is to contribute to the study of the ordering of localized classical spins coupled to itinerant electrons via the Zener double exchange model. The tendency to ferromagnetism resulting from electron motion is thwarted by the competition with antiferromagnetic superexchange interactions, leading to a variety of complex magnetic structures. First, the one dimensional model is studied as a function of the electronic density and a ferromagnetic “polaron” phase, each polaron containing three spins only, is shown to exist in a large part of the diagram even at low density. The tendency towards phase separation is studied in detail. In a second part we consider spin ordering in 3-leg ladders present in the structure of the Fe Ludwigite: Fe(3)O(2)BO(3). We examine the interplay between magnetic ordering, charge ordering and structural instability observed in this system. Finally, we consider the controversy between charge ordering and “Zener Polaron” ordering in the manganite La(0.5)Ca(0.5)MnO(3). It is shown that this two types of ordering are exclusive, except within an extremely reduced range of parameters.
Document type :
Theses
Complete list of metadata

Cited literature [30 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00086637
Contributor : Emmanuel Vallejo Castaneda <>
Submitted on : Wednesday, July 19, 2006 - 12:57:04 PM
Last modification on : Friday, December 18, 2020 - 1:34:03 PM
Long-term archiving on: : Tuesday, September 18, 2012 - 4:20:59 PM

Identifiers

  • HAL Id : tel-00086637, version 1

Collections

Citation

Emmanuel Vallejo Castaneda. Contribution à l'étude de l'ordre de spins, de charge et effets structuraux dans le modèle de double-échange : chaîne linéaire, échelles de spins et manganites.. Physique mathématique [math-ph]. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00086637⟩

Share

Metrics

Record views

358

Files downloads

316