Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Topology and Symmetry protected Materials (joint session O/TT)

O 55.8: Vortrag

Mittwoch, 20. März 2024, 16:45–17:00, HL 001

Manipulating Sunken Adatoms on Topological Insulator Bi2Se3 — Emma Grasser, •Adrian Weindl, Alfred J. Weymouth, and Franz J. Giessibl — Faculty of Physics, University of Regensburg, D-93053 Regensburg, Germany

Topological insulators (TIs) are a class of materials whose bulk is insulating, while their surface houses gapless topological boundary modes. These surface states possess a linear, spin-polarized dispersion relation and are thus protected from back-scattering by time-reversal symmetry. An open question remains whether surface doping of magnetic elements can suppress this topological protection. Nanostructures made from magnetic adatoms are proposed to enhance the magnetic scattering and may enable the observation of backscattering and the emergence of exotic quantum well states on the surfaces of topological insulators.

To this end, we study the manipulation characteristics of Fe adatoms on the surface of topological insulator Bi2Se3 with atomic force microscopy (AFM). The Fe adatoms adsorb in a sunken position in both hollow sites, rendering manipulation difficult. Nonetheless, we find a manipulation mechanism where the Fe atom is pulled from its sunken adsorption site towards the tip. We propose that the Fe atom develops a chemical bond to the probe tip while still bound to the surface as well. This state is stable for tip-sample distances of up to several hundreds of pm and can be used for controlled lateral manipulation. We demonstrate the controllability of manipulation by the construction of a small nanostructure.

Keywords: Atomic Force Microscopy; qPlus; Lateral Manipulation; Topological Insulator; Nanostructure