Discrete spectrum of edge states in a two-dimensional topological insulator
Phys. Rev. B 112, 155425 – Published 22 October, 2025
DOI: https://doi.org/10.1103/cf2t-vqcw
Abstract
The interaction model of two electrons in the edge states of a two-dimensional topological insulator is investigated. Both solutions of the Schrödinger equation and solutions of the Bethe-Salpeter equation at different values of the Fermi energy are considered. It is shown that for the Bethe-Salpeter equation, which takes into account the existence of the Fermi surface, there is a discrete spectrum in the system of two electrons. This phenomenon does not appear in the case of the Schrödinger equation. We found the bound-state energy for nonzero total momentum of electrons.
