Edge Reconstruction in a Quantum Spin Hall Insulator
Abstract
We study interaction-driven edge reconstruction in a quantum spin Hall insulator described by the Bernevig-Hughes-Zhang model with Kanamori-Hubbard interactions using the real-space density matrix renormalization group method in both the grand-canonical and canonical ensembles. For a two-dimensional cylinder with a smooth edge, we identify discrete particle-number transitions that lead to a spin-polarized edge state stabilized by an emergent ferromagnetic exchange interaction. The reconstruction is orbital-selective, occurring predominantly in the -orbital channel. Our results reveal a fully microscopic mechanism for emergent spin polarization at the edge that could compromise the topological protection of helical edge states by time reversal symmetry.
Cite
@article{arxiv.2508.10726,
title = {Edge Reconstruction in a Quantum Spin Hall Insulator},
author = {Rahul Soni and Matthias Thamm and Gonzalo Alvarez and Bernd Rosenow and Adrian Del Maestro},
journal= {arXiv preprint arXiv:2508.10726},
year = {2025}
}
Comments
6 pages with End Matter, 3 pages supplement, For associated data and code repository see: https://github.com/DelMaestroGroup/papers-code-BHZUEdgeReconstruction