Symmetry breaking in the Hubbard model : a bosonization approach

M.R.M.J. Traa, W.J. Caspers

LIVI R, Arianna Montorsi, Mario Rasetti

Masahisa Koga, Akihisa Koga

Pierre Funck

Gang Su

It is shown within the pseudospin framework that the U(1) phase symmetry and the pseudospin SU(2) symmetry in the Hubbard model at zero temperature are spontaneously broken away from half filling, which implies that the Hubbard model probably possesses some massless Goldstone bosons in its ground state.

Daniel González-Cuadra, Alexandre Dauphin, Przemysław R. Grzybowski +3 more

We study a one-dimensional model of interacting bosons coupled to a dynamical ${\mathbb{Z}}_{2}$ field, the ${\mathbb{Z}}_{2}$ Bose-Hubbard model, and analyze the interplay between spontaneous symmetry breaking and topological symmetry protection. In a previous work, we showed how this model exhibits a spontaneous breaking of the translational symmetry through a bosonic Peierls transition. Here we find how, at half filling, the resulting phase also displays topological features that coexist with the presence of long-range order and yields a topological bond order wave. Using both analytical and numerical methods, we describe the properties of this phase, showing that it cannot be adiabatically connected to a topological phase of noninteracting bosons, and thus constitutes an instance of an interaction-induced symmetry-breaking topological insulator.