Robust one-dimensionality at twin-grain-boundaries in MoSe$_{2}$

TL;DR

This paper models and analyzes the robust one-dimensional electron states at twin-grain-boundaries in MoSe₂, revealing their non-topological origin, interaction effects, and agreement with experimental ARPES data.

Contribution

It introduces a minimal three-orbital tight binding model for these states and uncovers their non-topological, interaction-driven behavior consistent with experiments.

Findings

Confined states are robust and ubiquitous across defects.

Only one confined electronic band is observed, contrary to topological expectations.

Interaction effects extend up to the lattice spacing, matching ARPES results.

Abstract

We show that 1D electron states confined at twin-grain-boundaries in MoSe$_{2}$ can be modeled by a three-orbital tight binding model including a minimum set of phenomenological hopping terms. The confined states are robust to the details of the defect hopping model, which agrees with their experimental ubiquity. Despite a valley Chern number which is finite and opposite on both sides of the defect, there is no topological protection of the confined states. This turns out to be an essential feature to have only one confined electronic band, in agreement with experiments, instead of two, as the bulk-edge correspondence would imply. Modeling the confined state as a 1D interacting electronic system allows us to unveil a mobile quantum impurity type behavior at energy scales beyond the Tomonaga-Luttinger liquid with an interaction range which extends up to the lattice spacing, in excellent agreement with ARPES measurements.