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】
Free