Hidden Breathing Kagome Topology in Hexagonal Transition Metal Dichalcogenides

TL;DR

This paper reveals that hexagonal transition metal dichalcogenides inherently contain a hidden breathing Kagome lattice structure that can host higher-order topological insulator states with protected corner states, opening new avenues for quantum physics in simple materials.

Contribution

It demonstrates the existence of a hidden breathing Kagome lattice and HOTI phase within natural h-TMD materials, previously observed only in artificial systems.

Findings

Identification of a hidden electronic Kagome lattice in h-TMDs

Demonstration of topologically protected corner states in nanoflakes

Potential for quantum entanglement in these topological states

Abstract

A Kagome lattice, formed by triangles of two different directions, is known to have many emergent quantum phenomena. Under the breathing anisotropy of bond strengths, this lattice can become a higher-order topological insulator (HOTI), which hosts topologically protected corner states. Experimental realizations of HOTI on breathing Kagome lattices have been reported for various artificial systems, but not for simple natural materials with an electronic breathing Kagome lattice. Here we prove that a breathing Kagome lattice and HOTI are hidden inside the electronic structure of hexagonal transition metal dichalcogenides (h-TMD). Due to the trigonal prismatic symmetry, $sp^2$-like hybrid d-orbitals create an electronic Kagome lattice with anisotropic inter-site and on-site hopping interactions. We demonstrate that HOTI h-TMD triangular nanoflakes host topologically protected corner states, which could be quantum-mechanically entangled with triple degeneracy. Because h-TMDS are easily synthesizable and stable at ambient conditions, our findings open new avenue for quantum physics based on simple condensed matter systems.