title: Haldane-Hubbard Mott Insulator: From Tetrahedral Spin Crystal to Chiral Spin Liquid.
abstract: Motivated by cold atom experiments on Chern insulators, we study the honeycomb lattice Haldane-Hubbard Mott insulator of spin-1/2 fermions using exact diagonalization and density matrix renormalization group methods. We show that this model exhibits various chiral magnetic orders including a wide regime of triple-Q tetrahedral order. Incorporating third-neighbor hopping frustrates and ultimately melts this tetrahedral spin crystal. From analyzing the low energy spectrum, many-body Chern numbers, entanglement spectra, and modular matrices, we identify the molten state as a chiral spin liquid (CSL) with gapped semion excitations. We formulate and study the Chern-Simons-Higgs field theory of the exotic CSL-to-tetrahedral spin crystallization transition.
authors.affiliation: Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
authors.forename: Ciarán
authors.initials: C
authors.lastname: Hickey
authors.affiliation: Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Cincio
authors.affiliation: School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Papić
authors.affiliation: Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.|Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
authors.forename: Arun
authors.initials: A
authors.lastname: Paramekanti