Fermionic Symmetry-Protected Topological Phase in a Two-Dimensional Hubbard Model

Academic Article

Abstract

  • © 2016 American Physical Society. We study the two-dimensional (2D) Hubbard model using exact diagonalization for spin-1/2 fermions on the triangular and honeycomb lattices decorated with a single hexagon per site. In certain parameter ranges, the Hubbard model maps to a quantum compass model on those lattices. On the triangular lattice, the compass model exhibits collinear stripe antiferromagnetism, implying d-density wave charge order in the original Hubbard model. On the honeycomb lattice, the compass model has a unique, quantum disordered ground state that transforms nontrivially under lattice reflection. The ground state of the Hubbard model on the decorated honeycomb lattice is thus a 2D fermionic symmetry-protected topological phase. This state - protected by time-reversal and reflection symmetries - cannot be connected adiabatically to a free-fermion topological phase.
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    Digital Object Identifier (doi)

    Author List

  • Chen CC; Muechler L; Car R; Neupert T; Maciejko J
  • Volume

  • 117
  • Issue

  • 9