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Complex charge density waves at Van Hove singularity on hexagonal lattices: Haldane-model phase diagram and potential realization in the kagome metals AV3Sb5 (A=K, Rb, Cs)

Yu-Ping Lin and Rahul M. Nandkishore
Phys. Rev. B 104, 045122 – Published 14 July 2021

Abstract

We investigate how the real and imaginary charge density waves interplay at the Van Hove singularity on the hexagonal lattices. A phenomenological analysis indicates the formation of 3Q complex orders at all three nesting momenta. Under a total phase condition, unequal phases at the three momenta break the rotation symmetry generally. The 3Q complex orders constitute a rich Haldane-model phase diagram. When effective time-reversal symmetries arise under 1-site translations, the Dirac semimetals are protected. The breakdown of these symmetries gaps the Dirac points and leads to the trivial and Chern insulator phases. These phases are deformations of purely real and imaginary orders, which exhibit trivial site and/or bond density and chiral flux orders, respectively. The exotic single-Dirac-point semimetals also appear along the gapless phase boundary. We further show that the theoretical model offers transparent interpretations of experimental observations in the kagome metals AV3Sb5 with A=K,Rb,Cs. The topological charge density waves may be identified with the complex orders in the Chern insulator phase. Meanwhile, the lower-temperature symmetry-breaking phenomena may be interpreted as the secondary orders from the complex order ground states. Our work sheds light on the nature of the topological charge density waves in the kagome metals AV3Sb5 and may offer useful indications to the experimentally observed charge orders in the future experiments.

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  • Received 21 April 2021
  • Revised 1 July 2021
  • Accepted 2 July 2021

DOI:https://doi.org/10.1103/PhysRevB.104.045122

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Yu-Ping Lin1 and Rahul M. Nandkishore1,2

  • 1Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
  • 2Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA

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Issue

Vol. 104, Iss. 4 — 15 July 2021

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