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Strong-coupling approach to mott transition of massless and massive Dirac fermions on honeycomb lattice

Adibi, E ; Sharif University of Technology | 2016

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  1. Type of Document: Article
  2. DOI: 10.1103/PhysRevB.93.075122
  3. Publisher: American Physical Society , 2016
  4. Abstract:
  5. Phase transitions in the Hubbard model and ionic Hubbard model at half-filling on the honeycomb lattice are investigated in the strong-coupling perturbation theory which corresponds to an expansion in powers of the hopping t around the atomic limit. Within this formulation we find analytic expressions for the single-particle spectrum, whereby the calculation of the insulating gap is reduced to a simple root finding problem. This enables high-precision determination of the insulating gap that does not require any extrapolation procedure. The critical value of Mott transition on the honeycomb lattice is obtained to be Uc≈2.38t. Studying the ionic Hubbard model at the lowest order, we find two insulating states, one with Mott character at large U and another with single-particle gap character at large ionic potential Δ. The present approach gives a critical gapless state at U=2Δ at lowest order. By systematically improving on the perturbation expansion, the density of states around this critical gapless phase reduces
  6. Keywords:
  8. Source: Physical Review B - Condensed Matter and Materials Physics ; Volume 93, Issue 7 , 2016 ; 10980121 (ISSN)
  9. URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.075122