Michael Pottoff (U. Hamburg)
Interacting Chern Insulator in Infinite Spatial Dimensions

Strong electron correlations and topological classification are two major research frontiers of condensed-matter theory. While much work has been done for noninteracting systems and for correlated one-dimensional models, much less is known for correlated systems in two and higher dimensions. Here, we discuss a generic model of a Chern insulator supplemented by a Hubbard interaction in arbitrary even dimension D and demonstrate that the model remains well defined and nontrivial in the infinite-D limit. Dynamical mean-field theory is applicable and predicts a phase diagram with a continuum of topologically different phases separating a correlated Mott insulator from the trivial band insulator. This provides us with exact results for a topologically nontrivial and strongly correlated system. We discuss various features, such as the elusive distinction between insulating and semimetal states, which are unconventional already in the noninteracting case. Topological phases are characterized by a nonquantized Chern density replacing the Chern number in the infinite-D limit.
 
see: Phys. Rev. Lett. 126, 196401 (2021)