Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: Focus Session: Designer Quantum Systems I (joint session O/TT)

TT 27.4: Talk

Tuesday, April 2, 2019, 11:45–12:00, H15

Constructing a Topological Insulator Atom-by-Atom — •Saoirsé Freeney — Condensed Matter and Interfaces, Princetonplein 1, 3584 CC Utrecht, The Netherlands

In a honeycomb lattice with alternating hopping strengths (Kekulé lattice), a gap in the energy dispersion is opened. Depending on the ratio of hopping parameters and the shape of the boundary, the band structure is either topologically trivial or non-trivial. Using scanning tunnelling microscopy, we realize Kekulé lattices through the coupling of artificial atoms, created by the careful arrangement of electron scatterers (carbon monoxide molecules) on a 2D electron gas (Cu(111) surface state). The electronic properties were probed using scanning tunnelling spectroscopy and differential conductance mapping. We show that the topologically non-trivial lattice features a robust edge state whereas the trivial equivalent does not. The experimental outcomes align well with results from tight binding and muffin tin calculations.