Dresden 2017 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 30: Two-dimensional materials IV (jointly with HL/TT)

DS 30.10: Vortrag

Mittwoch, 22. März 2017, 12:15–12:30, POT 51

Experimental realization and characterization of an electronic Lieb lattice — •Marlou Slot¹, Thomas Gardenier¹, Peter Jacobse¹, Guido van Miert², Sander Kempkes², Stephan Zevenhuizen¹, Cristiane Morais Smith², Daniel Vanmaekelbergh¹, and Ingmar Swart¹ — ¹Debye Institute for Nanomaterials Science, Utrecht University, Netherlands — ²Institute for Theoretical Physics, Utrecht University, Netherlands

Geometry, whether on the atomic or nanoscale, is a key factor for the electronic band structure of materials. For example, the honeycomb geometry leads to Dirac-type bands where the charge carriers behave as massless particles. Theoretical predictions are triggering the exploration of novel 2D geometries, such as graphynes, Kagomé and the Lieb lattice. The latter is the 2D analogue of the 3D lattice exhibited by perovskites; it is a square-depleted lattice, which is characterised by a band structure featuring Dirac cones intersected by a topological flat band. Whereas photonic and cold-atom Lieb lattices have been demonstrated, an electronic equivalent in 2D is difficult to realize in an existing material. Here, we report an electronic Lieb lattice formed by the surface state electrons of Cu(111) confined by an array of CO molecules positioned with a scanning tunneling microscope. Using scanning tunneling spectroscopy and wave-function mapping, we confirm the characteristic electronic structure of the Lieb lattice. The experimental findings are corroborated by muffin-tin and tight-binding calculations. At higher energy, second-order electronic patterns are observed, which are equivalent to a super-Lieb lattice.