Breakdown of Luttinger's theorem in two-orbital Mott insulators
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An analysis of Luttinger's theorem shows that – contrary to recent claims – it is not valid for a generic Mott insulator. For a two-orbital Hubbard model with two electrons per site the crossover from a non-magnetic correlated insulating phase (Mott or Kondo insulator) to a band insulator is investigated. Mott insulating phases are characterized by poles of the self-energy and corresponding zeros in the Greens functions defining a “Luttinger surface” which is absent for band insulators. Nevertheless, the ground states of such insulators with two electrons per unit cell are adiabatically connected.
PACS.71.10.-w Theories and models of many-electron systems 71.10.Fd Lattice fermion models (Hubbard model, etc.) 71.30.+h Metal-insulator transitions and other electronic transitions
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