Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 1: Topological Insulators 1 (joint session TT/HL)

TT 1.2: Talk

Monday, March 16, 2020, 09:45–10:00, HSZ 03

Correlated Ground States in Maximally Symmetric Flat Bands of 2D Topological Insulators — •Nikolaos Stefanidis and Inti Sodemann — Max-Planck-Institut für Physik komplexer Systeme,Nöthnitzer Str. 38, 01187 Dresden

We study the many body-problem in partially filled topological flat bands that are maximally symmetric realisations of two dimensional time-reversal invariant insulators. These bands can be viewed as two flat bands with opposite Chern numbers that are forced to be degenerate by time-reversal-symmetry. For half-filled bands we develop a mean field description of states that spontaneously break time reversal symmetry and their competition with translationally broken symmetry states and superconductors. At general fillings we prove a rigorous theorem dictating the absence of exact topological degeneracy for any translational and time reversal invariant two-body Hamiltonian. We also solve exactly the two body problem, which turns out to display a remarkable correlation between the center-of-mass and relative-coordinate degrees of freedom of the two particles.