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 building blocks. 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 successful synthesis of a metastable pentagonal 2D material, the monolayer pentagonal PdTe2, by symmetry-driven epitaxy. Scanning tunneling microscopy and complementary spectroscopy measurements are used to characterize the monolayer pentagonal PdTe2, which demonstrates well-ordered low-symmetry atomic arrangements and is stabilized by lattice matching with the underlying Pd(100) substrate. Theoretical calculations, along with angle-resolved photoemission spectroscopy, reveal monolayer pentagonal PdTe2 is a semiconductor with an indirect bandgap of 1.05 eV. Our work opens an avenue for the synthesis of pentagon-based 2D materials and gives opportunities to explore their applications such as multifunctional nanoelectronics.
@article{arxiv.2408.04095,
title = {A Metastable Pentagonal 2D Material Synthesized by Symmetry-Driven Epitaxy},
author = {Lina Liu and Yujin Ji and Marco Bianchi and Saban M. Hus and Zheshen Li and Richard Balog and Jill A. Miwa and Philip Hofmann and An-ping Li and Dmitry Y. Zemlyanov and Youyong Li and Yong P. Chen},
journal= {arXiv preprint arXiv:2408.04095},
year = {2024}
}