Orbital-selective Mott transition in multiband systems: Slave-spin representation and dynamical mean-field theory

Article

关键词: PERIODIC ANDERSON MODEL;    INFINITE DIMENSIONS;    HUBBARD-MODEL;    CA2-XSRXRUO4;    POINT;   

DOI  :  10.1103/PhysRevB.72.205124

来源: SCIE

【 摘 要 】

We examine whether the Mott transition of a half-filled, two-orbital Hubbard model with unequal bandwidths occurs simultaneously for both bands or whether it is a two-stage process in which the orbital with narrower bandwith localizes first (giving rise to an intermediate orbital-selective Mott phase). This question is addressed using both dynamical mean-field theory and a representation of fermion operators in terms of slave quantum spins, followed by a mean-field approximation (similar in spirit to a Gutzwiller approximation). In the latter approach, the Mott transition is found to be orbital selective for all values of the Coulomb exchange (Hund) coupling J when the bandwidth ratio is small and only beyond a critical value of J when the bandwidth ratio is larger. Dynamical mean-field theory partially confirms these findings, but the intermediate phase at J=0 is found to differ from a conventional Mott insulator, with spectral weight extending down to arbitrary low energy. Finally, the orbital-selective Mott phase is found, at zero temperature, to be unstable with respect to an interorbital hybridization V and replaced at small V by a state with a large effective mass (and a low quasiparticle coherence scale) for the narrower band.

【 授权许可】

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