Strong correlation, Bloch bundle topology, and spinless Haldane–Hubbard model

Abstract

Different realizations of the Hubbard operators in different Hilbert spaces give rise to various microscopic lattice electron models driven by strong correlations. In terms of the Gutzwiller projected electron operators, the most familiar examples are the conventional t−J model and the BCS-Hubbard model at strong coupling. Here we focus on the spin-dopon representation of the Hubbard operators. In this case the no double occupancy (NDO) constraint can be reexpressed as a Kondo interaction. As an explicit example, the effective low-energy action is derived in terms of itinerant spinless fermions (dopons) strongly interacting with localized lattice spins. The spontaneous breaking of the time-reversal symmetry reduces that action to one describing a spinless version of the Haldane–Hubbard topological theory. This result suggests that the topologically nontrivial U(1) Bloch bundle associated with this model can be realized dynamically due to the presence of strong correlations even in the absence of any external local or global fluxes.