Diverging dc conductivity due to a flat band in a disordered system of pseudospin-1 Dirac-Weyl fermions

Máté Vigh, László Oroszlány, Szabolcs Vajna, Pablo San-Jose, Gyula Dávid, József Cserti, Balázs Dóra

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Several lattices, such as the dice or the Lieb lattice, possess Dirac cones and a flat band crossing the Dirac point, whose effective model is the pseudospin-1 Dirac-Weyl equation. We investigate the fate of the flat band in the presence of disorder by focusing on the density of states (DOS) and dc conductivity. While the central hub site does not reveal the presence of the flat band, the sublattice resolved DOS on the noncentral sites exhibits a narrow peak with height ∼1/√g with g the dimensionless disorder variance. Although the group velocity is zero on the flat band, the dc conductivity diverges as ln(1/g) with decreasing disorder due to interband transitions around the band touching point between the propagating and the flat band. Generalizations to higher pseudospin are given.

Original languageEnglish
Article number161413
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number16
Publication statusPublished - Oct 30 2013


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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