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Abstract: We investigate the Hubbard model on the honeycomb lattice with intrinsic spinorbit interactions as a paradigm for two-dimensional topological bandinsulators in the presence of interactions. Applying a combination ofHartree-Fock theory, slave-rotor techniques, and topological arguments, we showthat the topological band insulating phase persists up to quite stronginteractions. Then we apply the slave-rotor mean-field theory and find a Motttransition at which the charge degrees of freedom become localized on thelattice sites. The spin degrees of freedom, however, are still described by theoriginal Kane-Mele band structure. Gauge field effects in this region play animportant role. When the honeycomb layer is isolated then the spin sectorbecomes already unstable toward an easy plane Neel order. In contrast, if thehoneycomb lattice is surrounded by extra -screening- layers with gaplessspinons, then the system will support a fractionalized topological insulatorphase with gapless spinons at the edges. For large interactions, we derive aneffective spin Hamiltonian.



Author: Stephan Rachel, Karyn Le Hur

Source: https://arxiv.org/







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