Interaction effects in a 1D flat band at a topological crystalline step edge

Abstract

Step edges of topological crystalline insulators can be viewed as predecessors of higher-order topology, as they embody one-dimensional edge channels embedded in an effective three-dimensional electronic vacuum emanating from the topological crystalline insulator. Using scanning tunneling microscopy and spectroscopy we investigate the behaviour of such edge channels in Pb${}_{1-x}$Sn${}_x$Se under doping. Once the energy position of the step edge is brought close to the Fermi level, we observe the opening of a correlation gap. The experimental results are rationalized in terms of interaction effects which are enhanced since the electronic density is collapsed to a one-dimensional channel. This constitutes a unique system to study how topology and many-body electronic effects intertwine, which we model theoretically through a Hartree-Fock analysis.

arXiv comment8 pages, 5 figures (main text) and 5 pages, 6 figures (Supplementary Material)

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Cited by in corpus (4)

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• Sensing the binding and unbinding of anyons at impurities