Interplay of charge and spin fluctuations of strongly interacting electrons on the kagome lattice

Frank Pollmann, Krishanu Roychowdhury, Chisa Hotta, Karlo Penc

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We study electrons hopping on a kagome lattice at third filling described by an extended Hubbard Hamiltonian with on-site and nearest-neighbor repulsions in the strongly correlated limit. As a consequence of the commensurate filling and the large interactions, each triangle has precisely two electrons in the effective low-energy description, and these electrons form chains of different lengths. The effective Hamiltonian includes the ring exchange around the hexagons as well as the nearest-neighbor Heisenberg interaction. Using large-scale exact diagonalization, we find that the effective model exhibits two phases: If the charge fluctuations are small, the magnetic fluctuations confine the charges to short loops around hexagons, yielding a gapped charge-ordered phase. When the charge fluctuations dominate, the system undergoes a quantum phase transition to a resonating plaquette phase with ordered spins and gapless spin excitations. We find that a peculiar conservation law is fulfilled: the electron in the chains can be divided into two sublattices, and this division is conserved by the ring exchange term.

Original languageEnglish
Article number035118
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number3
DOIs
Publication statusPublished - Jul 14 2014

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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