New functionals for the anisotropic Heisenberg model / Novos funcionais para o modelo de Heisenberg anisotrópico

AUTOR(ES)

Guilherme Nery Prata

DATA DE PUBLICAÇÃO

2008

RESUMO

The Heisenberg Model is generally recognized in the study of electromagnetism with origin in localized magnetic moments. Similar to the well known classical Ising model, it incorporates, however, quantum flutuations. We are interested in antiferromagnetic systems described by the Heisenberg Hamiltonian with exchange anisotropy and, eventually, non-null magnetizations. In this work, we deal with non-homogeneous systems with impurities. For this, we use Density Functional Theory and the Local Spin Aproximation (LSA), which provide a methodology for obtaining results of a non-homogeneous system from known results of the same but homogeneous system. Initially, we work with a functional provided by Spin Wave Theory on the LSA approximation, valid for anisotropies with XXZ simmetry and null magnetization. After that, we deal with the possibility of building a functional on LSA approximation valid also for exchange anisotropy but with an additional: applicable for non-null magnetizations.

ASSUNTO(S)

density-functional theory heisenberg model física de matéria condensada modelo de heisenberg condensed matter physics teoria do funcional da densidade

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