Structure électronique des matériaux ferromagnétiques de type pérovskite double: Étude par la technique DFT+U

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Résumé (Français et/ou Anglais) : Using first-principle calculations within the framework of density functional theory (DFT), the full-potential linearized augmented plane-wave (FP-LAPW) method have been performed to investigate structural, electronic and magnetic properties of the double perovskite Ca2CoMoO6 and Ca2MnMoO6 within both generalized gradient approximation (GGA) and GGA + U (Hubbard Coulomb onsite correction) were considered. The structural stability ,magnetic ordering were reported on double perovskite Ca2CoMoO6 ,our calculation reveal that the compound is half-metallic (HM) and half semiconductor (HSC) ferromagnetic (FM) semiconductor in the monoclinic structure (P21/n) with a total magnetic moment of 6.0 (μB) using GGA-PBE and GGA-PBE+U. Using the Vampire code, an estimation of exchange couplings and magnetic Curie temperature were calculated. In the other hand, an investigation of structural, electronic and magnetic properties of Ca2MnMoO6 compound were performed, different spin configurations (ferromagnetic (FM), ferrimagnetic (FiM), and antiferromagnetic (AFM1, AFM2) were considered, the value of the Hubbard Coulomb U parameter was varied in the range of 1-4 eV. We find the FM phase has a half metallic character with a net magnetic moment of 5.0 μB while The ground state of Ca2MnMoO6 compound is found to be antiferromagnetic and insulating with the (AFM1) state the most favorable. In the (AFM1) spin configuration, Ca2MnMoO6 compound has a semiconductor nature
Doctorat en Sciences