Orbital polaron in double-exchange ferromagnets

Article

关键词: MEAN-FIELD THEORY;    QUANTUM ANTIFERROMAGNET;    INSULATOR-TRANSITION;    INFINITE DIMENSIONS;    HUBBARD-MODEL;    MOTION;    HOLE;   

DOI  :  10.1103/PhysRevB.86.235114

来源: SCIE

【 摘 要 】

We investigate the spectral properties of the two-orbital Hubbard model, including the pair hopping term, by means of the dynamical mean field method. This Hamiltonian describes materials in which ferromagnetism is realized by the double-exchange mechanism, as for instance manganites, nickelates, or diluted magnetic semiconductors. The spectral function of the unoccupied states is characterized by a specific equidistant three peak structure. We emphasize the importance of the double hopping term on the spectral properties. We show the existence of a ferromagnetic phase due to electron doping near n = 1 by the double-exchange mechanism. A quasiparticle excitation at the Fermi energy is found that we attribute to what we will call an orbital polaron. We derive an effective spin-pseudospin Hamiltonian for the two-orbital double-exchange model at n = 1 filling to explain the existence and dynamics of this quasiparticle. DOI: 10.1103/PhysRevB.86.235114

【 授权许可】

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