Regensburg 2025 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

O: Fachverband Oberflächenphysik

O 49: Poster Nanostructures at Surfaces

O 49.5: Poster

Tuesday, March 18, 2025, 18:00–20:00, P2

Exploring Topological Boundary Modes in Atomically Assembled Quantum Structures — •Adrian Weindl, Christoph Setescak, and Franz J. Giessibl — Faculty of Physics, University of Regensburg, D-93053 Regensburg, Germany

Single-atom and single-molecule manipulation enables the construction of quantum simulators: artificial structures assembled atom-by-atom or molecule-by-molecule to emulate key properties of complex systems that are challenging or impossible to fabricate directly. Using scanning tunneling microscopy (STM) and atomic force microscopy (AFM), we create two atomic-scale structures from individual CO molecules on Cu(111): a 1D Su-Schrieffer-Heeger (SSH) chain and a 2D Kagome lattice.

The 1D SSH chain represents a fundamental system capable of hosting topological boundary modes. We investigate the interaction between these boundary modes and the AFM tip. As the boundary modes are spatially localized and pinned in energy, they are not expected to undergo chemical bonding, unlike the bulk states of the chain, which may exhibit such interactions.

The 2D Kagome lattice on Cu(111) was initially proposed as a higher-order topological insulator, a classification that remains under debate. Through STM and AFM measurements, we aim to contribute to this ongoing discussion by introducing defects and analyzing the bonding behavior of the purported topological corner modes.

Keywords: Atomic Force Microscopy; Scanning Tunneling Microscopy; Topological Insulators; Nanostructures