Mémoires de Fin d’Etudes
Etablissement
Université d’Oran1 - Ahmed Ben Bella
Affiliation
Département de Physique
Auteur
SI LAKHAL, Bahia
Directeur de thèse
ABADA A.
Filière
Physique
Diplôme
Doctorat
Titre
Dynamic correlation function in the heisenberg spin-12 antiferromagnetic model
Mots clés
Quantum groups; XXZ Heisenberg model; Quantum spin chains; Quantum a¢ ne algebra; Dynamic correlation functions; Dynamic structure functions; Four spinon dynamic correlation function; Sum rules for the dynamic structure function.
Résumé
We derive the exact expression of the four-spinon contribution S4 to the dynamic correlation function S (DCF) of the spin-1/2 antiferromagnetic Heisenberg XXZ model using the quantum a¢ ne algebra symmetry present in the model. First, an exact expression for the n-spinon contribution is given in the form of contour integrals. After we display previous known results concerning the two-spinon contribution S2, we specialize the n-spinon formula to the case n = 4. An explicit series representation of this contribution in the isotropic limit is given and shown to be free from divergences. We then go to describe the behavior of the exact isotropic four-spinon DCF S4 as a function of the neutron energy! and momentum transfer k. For this, Monte Carlo integration methods are used. We also determine the four-spinon continuum, the extent of the region in the (k; !) plane outside which S4 is identically zero.
Date de soutenance
2006
Cote
TH2226
Pagination
XI-86F.
Format
30 cm
Notes
ABSTRACT.BIBLIOG.81-86F.ANNEXES.
Statut
Soutenue