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O: Fachverband Oberflächenphysik
O 47: 2D Materials II: Growth, Structure and Substrate Interaction I
O 47.9: Talk
Wednesday, March 29, 2023, 12:30–12:45, GER 37
A Metastable Pentagonal 2D Material Synthesized by Symmetry-Driven Epitaxy — •Lina Liu1,2 and Yong Chen1,2 — 1Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, 47907, USA — 2Institute of Physics and Astronomy and Villum Centers for Dirac Materials and for Hybrid Quantum Materials and Devices, Aarhus University, 8000 Aarhus-C, Denmark
Most two-dimensional (2D) materials experimentally studied so far have hexagons as their building blocks. Only a few exceptions, such as PdSe2, are lower in energy in pentagonal phases and exhibit pentagons as the building blocks. Such pentagonal 2D materials demonstrate unprecedented properties and unique applications originated from low-symmetry lattice geometries. While theory has predicted a large number of pentagonal 2D materials, many of them are metastable and their experimental realization is difficult. Here, we report the first synthesis of a metastable pentagonal 2D material, the pentagonal PdTe2 monolayer, by symmetry-driven epitaxy. Scanning tunneling microscopy is used to characterize the monolayer pentagonal PdTe2, which demonstrates well-ordered low-symmetry atomic arrangements. Theoretical calculations, along with angle-resolved photoemission spectroscopy, reveal the band structures of monolayer pentagonal PdTe2. In contrast to the narrow bandgap of monolayer hexagonal PdTe2, monolayer pentagonal PdTe2 is a semiconductor with a much bigger indirect bandgap of 1.08 eV. Our work opens an avenue for the synthesis of new, pentagon-based 2D materials and gives great opportunities to explore their applications such as multifunctional electronics.