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arXiv:0903.3390 · Physical Review Letters

Determinant Quantum Monte Carlo Study of the Orbitally Selective Mott Transition

Karim Bouadim, G. G. Batrouni, R. T. Scalettar

Published Jun 4, 2009• 20 citations
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Abstract

We study the conductivity, density of states, and magnetic correlations of a two-dimensional, two-band fermion Hubbard model using determinant quantum Monte Carlo (DQMC) simulations. We show that an orbitally selective Mott transition (OSMT) occurs in which the more weakly interacting band can be metallic despite complete localization of the strongly interacting band. The DQMC method allows us to test the validity of the use of a momentum independent self-energy which has been a central approximation in previous OSMT studies. In addition, we show that long range antiferromagnetic order (LRAFMO) is established in the insulating phase, similar to the single band, square lattice Hubbard Hamiltonian. Because the critical interaction strengths for the onset of insulating behavior are much less than the bandwidth of the itinerant orbital, we suggest that LRAFMO plays a key role in the transitions.

DOI
10.1103/physrevlett.102.226402

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Abstract Using high‐precision quantum Monte Carlo (QMC) simulations within the framework of dynamical mean field theory (DMFT), we show that the anisotropic degenerate two‐orbital Hubbard model contains two consecutive orbital‐selective Mott transitions (OSMTs) even in the absence of spin‐flip terms and pair‐hopping processes. In order to reveal the second transition we carefully analyze the low‐frequency part of the self‐energy and the local spectral functions. This paper extends our previous work to lower temperatures. We discuss the nature – in particular the order – of both Mott transitions and list various possible extensions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)