Reduction of $\mathbb{Z}$ classification of a two-dimensional weak topological insulator - real-space DMFT study -

摘要

One of the remarkable interaction effects on topological insulators is thereduction of topological classification in free-fermion systems. We addressthis issue in a bilayer honeycomb lattice model by taking into accounttemperature effects on the reduction. Our analysis, based on the real-spacedynamical mean field theory, elucidates the following results. (i) Even whenthe reduction occurs, the winding number defined by the Green's function cantake a nontrivial value at zero temperature. (ii) The winding number taking thenontrivial value becomes consistent with the absence of gapless edge modes dueto Mott behaviors emerging only at the edges. (iii) Temperature effects canrestore the gapless edge modes, provided that the energy scale of interactionsis smaller than the bulk gap. In addition, we observe the topological edge Mottbehavior only in some finite temperature region.