Robust zero-energy modes in an electronic higher-order topological insulator

Area of Science:

• Condensed Matter Physics
• Quantum Simulation
• Materials Science

Background:

• Quantum simulators are crucial for studying complex quantum materials.
• Existing platforms include ultracold atoms and photonics, but electronic simulators are emerging.
• Higher-order topological insulators (HOTIs) represent a novel class of topological materials.

Purpose of the Study:

• To experimentally realize an electronic higher-order topological insulator (HOTI).
• To demonstrate the emergence of topological states in engineered lattice structures.
• To explore the properties and protection mechanisms of corner modes in HOTIs.

Main Methods:

• Fabrication of a breathing kagome lattice using carbon monoxide molecules on a Cu(111) surface via scanning tunneling microscopy.
• Engineering alternating weak and strong bonds within the lattice.
• Characterization of the emergent topological states and their symmetries.

Main Results:

• Successful realization of an electronic HOTI.
• Observation of a topological state localized at the corners of the non-trivial lattice configuration.
• Demonstration that the corner mode is protected by generalized chiral symmetry, exhibiting robustness.

Conclusions:

• The experimental realization of an electronic HOTI using engineered molecular lattices is achieved.
• This approach offers a versatile platform for designing artificial lattices and discovering new quantum phases.
• The findings contribute to the development of electronic quantum simulators and the understanding of topological matter.