Fermionic Symmetry-Protected Topological Phase in a Two-Dimensional Hubbard Model.
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.
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.|Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Cheng-Chien
CC
Chen
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
Lukas
L
Muechler
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
Roberto
R
Car
Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA.
Titus
T
Neupert
Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.|Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.|Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
Joseph
J
Maciejko