Topological states in engineered atomic lattices

TL;DR

This paper demonstrates the creation of artificial atomic lattices using STM to realize topological models like the polyacetylene chain and Lieb lattice, enabling controlled studies of topological states.

Contribution

It introduces a method to fabricate and probe topological lattice models in atomic-scale engineered systems using STM and STS.

Findings

Successfully fabricated vacancy lattices with atomic precision

Realized topological domain wall states in a polyacetylene analogue

Observed flat bands in the Lieb lattice model

Abstract

Topological materials exhibit protected edge modes that have been proposed for applications in for example spintronics and quantum computation. While a number of such systems exist, it would be desirable to be able to test theoretical proposals in an artificial system that allows precise control over the key parameters of the model. The essential physics of several topological systems can be captured by tight-binding models, which can also be implemented in artificial lattices. Here, we show that this method can be realized in a vacancy lattice in a chlorine monolayer on a Cu(100) surface. We use low-temperature scanning tunneling microscopy (STM) to fabricate such lattices with atomic precision and probe the resulting local density of states (LDOS) with scanning tunneling spectroscopy (STS). We create analogues of two tight-binding models of fundamental importance: The polyacetylene (dimer) chain with topological domain wall states, and the Lieb lattice, featuring a lattice pseudospin 1 system with a flat electron band. These results provide the first steps in realizing designer quantum materials with tailored properties.