Reduction of Z classification of a two-dimensional weak topological insulator: Real-space dynamical mean-field theory study

摘要

One of the remarkable interaction effects on topological insulators is the reduction of topological classificationin free-fermion systems. We address this issue in a bilayer honeycomb lattice model by taking into accounttemperature effects on the reduction. Our analysis, based on the real-space dynamical mean-field theory,elucidates the following results. (ⅰ) Even when the reduction occurs, the winding number defined by the Green’sfunction can take a nontrivial value at zero temperature. (ⅱ) The winding number taking the nontrivial valuebecomes consistent with the absence of gapless edge modes due to Mott behaviors emerging only at the edges.(ⅲ) Temperature effects can restore the gapless edge modes, provided that the energy scale of interactionsis smaller than the bulk gap. In addition, we observe the topological edge Mott behavior only in somefinite-temperature region.