Realization of Flat Band with Possible Nontrivial Topology in Electronic Kagome Lattice

TL;DR

This paper reports the experimental realization of a flat band with potential nontrivial topology in an electronic Kagome lattice on twisted multilayer silicene, revealing localized electrons and edge states that could enable fractional Chern insulators.

Contribution

It demonstrates the first experimental observation of a flat band with possible nontrivial topology in an electronic Kagome lattice on twisted multilayer silicene.

Findings

Observation of a flat band in electronic Kagome lattice.

Detection of a robust one-dimensional edge state.

Potential implications for fractional Chern insulators.

Abstract

The energy dispersion of fermions or bosons vanishes in momentum space if destructive quantum interference occurs in a frustrated Kagome lattice with only nearest-neighbour (NN) hopping. A discrete flat band (FB) without any dispersion is consequently formed, promising emergence of fractional quantum Hall states (FQHS) at high temperatures. Here, we report experimental realization of a FB with possible nontrivial topology in an electronic Kagome lattice on a twisted multilayer silicene. The electrons are localized in the Kagome lattice due to quantum destructive interference, and thus, their kinetic energy is quenched, which gives rise to a FB peak in density of states. A robust and pronounced one-dimensional edge state has been revealed at Kagome edge, which resides at higher energy than the FB. Our observations of the FB and the exotic edge state in electronic Kagome lattice open up the possibility towards the realization of fractional Chern insulators in two-dimensional materials.