Dirac Electrons in a Dodecagonal Graphene Quasicrystal
Abstract
Quantum states of quasiparticles in solids are dictated by symmetry. Thus, a discovery of unconventional symmetry can provide a new opportunity to reach a novel quantum state. Recently, Dirac and Weyl electrons have been observed in crystals with discrete translational symmetry. Here we experimentally demonstrate Dirac electrons in a two-dimensional quasicrystal without translational symmetry. A dodecagonal quasicrystal was realized by epitaxial growth of twisted bilayer graphene rotated exactly 30 degree. The graphene quasicrystal was grown up to a millimeter scale on SiC(0001) surface while maintaining the single rotation angle over an entire sample and was successfully isolated from a substrate, demonstrating its structural and chemical stability under ambient conditions. Multiple Dirac cone replicated with the 12-fold rotational symmetry were observed in angle resolved photoemission spectra, showing its unique electronic structures with anomalous strong interlayer coupling with quasi-periodicity. Our study provides a new way to explore physical properties of relativistic fermions with controllable quasicrystalline orders.
Cite
@article{arxiv.1804.04261,
title = {Dirac Electrons in a Dodecagonal Graphene Quasicrystal},
author = {Sung Joon Ahn and Pilkyung Moon and Tae-Hoon Kim and Hyun-Woo Kim and Ha-Chul Shin and Eun Hye Kim and Hyun Woo Cha and Se-Jong Kahng and Philip Kim and Mikito Koshino and Young-Woo Son and Cheol-Woong Yang and Joung Real Ahn},
journal= {arXiv preprint arXiv:1804.04261},
year = {2018}
}
Comments
20 pages, 4 figures