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TT: Fachverband Tiefe Temperaturen

TT 61: Topology – Poster

TT 61.10: Poster

Mittwoch, 11. März 2026, 15:00–17:00, P4

Topologically nontrivial phase induced by disorder in a one-dimensional system — •Lars Emmrich and Michael Potthoff — Department of Physics, University of Hamburg, Germany

The Su-Schrieffer-Heger model with additional local, uncorrelated, binary-alloy site disorder of strength W is a prototypical model for studying the phase diagrams of disordered topological band insulators. With the topological-Hamiltonian approach and with the twisted-boundary-conditions approach, we employ two complementary techniques to compute the winding number ν, a topological invariant. Starting from the topologically nontrivial phase with ν=1 in the clean limit (W=0), we find that, as W increases, the system undergoes a transition to a trivial phase with ν=0, followed by a second transition to a nontrivial phase with ν =1. Importantly, the latter phase cannot be connected continuously to the clean limit and thus represents a novel, disorder-induced phase, because the nontrivial topology is carried by the zeros of the single-electron Green’s function.

Keywords: Su-Schrieffer-Heeger Model; Magnetic Disorder; Winding Number; Green's Function Zeros