Topological nature of in-gap bound states in disordered large-gap monolayer transition metal dichalcogenides

TL;DR

This paper models disordered monolayer transition metal dichalcogenides to reveal in-gap bound states with topological properties, potentially enabling room-temperature valley- and spin-qubits.

Contribution

It introduces a physical model demonstrating topological in-gap bound states in disordered large-gap TMDs, highlighting their potential for quantum computing.

Findings

Existence of at least two in-gap bound states with opposite angular momentum.

Bound states are strongly influenced by spin-valley coupling and hole size.

Topological insulator features confirmed by Chern number and energy dispersion analysis.

Abstract

We propose a physical model based on disordered (a hole punched inside a material) monolayer transition metal dichalcogenides (TMDs) to demonstrate a large-gap quantum valley Hall insulator. We find an emergence of bound states lying inside the bulk gap of the TMDs. They are strongly affected by spin-valley coupling, rest- and kinetic- mass terms and the hole size. In addition, in the whole range of the hole size, at least two in-gap bound states with opposite angular momentum, circulating around the edge of the hole, exist. Their topological insulator (TI) feature is analyzed by the Chern number, characterized by spacial distribution of their probabilities and confirmed by energy dispersion curves (Energy vs. angular momentum). It not only sheds light on overcoming low-temperature operating limitation of existing narrow-gap TIs, but also opens an opportunity to realize valley- and spin- qubits.