Theoretical study of highly correlated electron systems

Author(s)

Cesar José Calderon Filho

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2014-09-15

Examining board members

Gaston Eduardo Barberis; Paulo Pureur Neto; Antonio Gomes de Souza Filho; Mario Eusébio Foglio; Kleber Roberto Pirota

• Advisor: Eduardo Granado Monteiro da Silva; Gaston Eduardo Barberis

Abstract

This work is devoted to the study of an special type of strongly correlated electrons\' compounds, namely the multiferroics. We analyze theoretically those substances, and we study a particular family of them, the LiMPO4 (M: Mn, Fe, Co, Ni) family. We focus particularly in the Mn compound, LiMnPO4, where we use existing and newly obtained data from Inelastic Neutron Scattering, Magnetization, Raman Scattering and Electron Spin Resonance to model the magnetic interactions in the material. The results in single crystals of this compound allow us to refine the knowledge of the magnetic interactions in LiMnPO4. Our model develops a calculation that fits together the new Raman experiments and the already published INS, arriving to a clear interpretation of the role of the exchange parameters in the chosen material. We expect that our calculation will be extended in the future to the whole family and to other compounds. This thesis tried to be self-contained, so we included some material that can be useful for the readers and future continuators of this work (AU)