Authors
Avedis Neehus, Frank Pollmann, Johannes Knolle
Published in
Physical review letters. Volume 135. Issue 12. Pages 126604. Sep 19, 2025.
Abstract
We investigate a model of Dirac fermions with mass impurities that open a global topological gap even in the dilute limit. Surprisingly, we find that the chirality of this mass term, i.e., the sign of the Chern number, can be reversed by tuning the magnitude of the single-impurity scattering. Consequently, the disorder induces a phase disconnected from the simple clean limit of the topological insulator, which is achieved via an impurity resonance inducing additional bands with Chern number 2. Thus, we call this impurity induced phase a genuine topological Anderson insulator. In seeming contradiction to the expectation that mass disorder is an irrelevant perturbation to the Dirac semimetal, the tricritical point separating these two Chern insulating phases and a thermal metal phase is located at zero impurity density and connected to the appearance of a zero energy bound state in the continuum that corresponds to a perfectly resonant mass impurity. Our conclusions based on the T-matrix expansion are substantiated by large scale Chebyshev-polynomial Green's function numerics. We discuss possible experimental platforms.
PMID:
41046400
Bibliographic data and abstract were imported from PubMed on 06 Oct 2025.
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