Time-reversal-invariant Hofstadter-Hubbard model with ultracold fermions

We consider the time-reversal-invariant Hofstadter-Hubbard model which can be realized in cold-atom experiments [1]. In these experiments, an additional staggered potential and an artificial Rashba-type spin-orbit coupling are available. Without interactions, the system exhibits various phases such as topological and normal insulator, metal as well as semi-metal phases with two or even more Dirac cones. Using a combination of real-space dynamical mean-field theory and analytical techniques, we discuss the effect of on-site interactions and determine the corresponding phase diagram. In particular, we investigate the semi-metal to antiferromagnetic insulator transition and the stability of different topological insulator phases in the presence of strong interactions. We compute spectral functions which allow us to study the edge states of the strongly correlated topological phases. [1] Daniel Cocks, Peter P. Orth, Stephan Rachel, Michael Buchhold, Karyn Le Hur, and Walter Hofstetter, arXiv:1204.4171 (2012) (accepted for Phys. Rev. Lett.)