Ferromagnetic polarons in La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3

Article

关键词: NEUTRON-DIFFRACTION;    PHASE-SEPARATION;    DOUBLE EXCHANGE;    JAHN-TELLER;    MANGANITES;    CHARGE;    TRANSITION;    OXIDES;    MODELS;   

DOI  :  10.1103/PhysRevB.67.220404

来源: SCIE

【 摘 要 】

Unrestricted Hartree-Fock calculations on La1-xCaxMnO3 (x=0.5 and x=0.67) in the full magnetic unit cell show that the magnetic ground states of these compounds consist of ferromagnetic molecules or polarons ordered in herring-bone patterns. Each polaron consists of either two or three Mn ions separated by O- ions with a magnetic moment opposite to those of the Mn ions. Ferromagnetic coupling within the polarons is strong, while coupling between them is relatively weak. Magnetic moments on the Mn ions range between 3.8mu(b) and 3.9 mu(B) in the x=0.5 compound and moments on the O- ions are -0.7mu(B). Each polaron has a net magnetic moment of 7.0mu(B), in a good agreement with recently reported magnetization measurements from electron microscopy. The polaronic nature of the electronic structure reported here is obviously related to the Zener polaron model recently proposed for Pr0.60Ca0.40MnO3 on the basis of neutron-scattering data.

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