SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 36: Topological Insulators

TT 36.8: Talk

Wednesday, March 29, 2023, 17:00–17:15, HSZ 103

Spectral functions of a topological Fermi-Hubbard model in one dimension — •David Mikhail and Stephan Rachel — School of Physics, University of Melbourne, Parkville, VIC 3010, Australia

We study the effects of electron-electron interactions on the charge excitation spectrum of the spinful Su-Schrieffer-Heeger model, a prototype of a one-dimensional bulk obstructed topological insulator. In light of recent progress in the fabrication of dopant-based quantum simulators we focus on experimentally detectable signatures of interacting topology in finite lattices. Importantly, these semiconductor platforms allow for local high-precision measurements using scanning tunnelling spectroscopy (STS). To this end we use Lanczos-based exact diagonalization to calculate the single-particle spectral function in real space which generalizes the local density of states to interacting systems. Its spatial and spectral resolution allows for the direct investigation and identification of edge states. While the non-trivial topology is manifested in zero-energy spin-like edge excitations for any finite interaction strength, our analysis of the spectral function shows that the single-particle charge excitations are gapped out on the boundary. Despite the loss of topological protection, we find that these edge excitations are quasiparticle-like as long as they remain within the bulk gap and as such serve as an indicating signature of the correlated topological phase measurable in single-particle measurement techniques such as STS. Our results are available at Phys. Rev. B 106, 195408 (2022).