Triggering a global density wave instability in graphene via local symmetry-breaking

Science Advances, 8, eabm5180 (2022) Two-dimensional quantum materials offer a robust platform for investigating the emergence of symmetry-broken ordered phases owing to the high tuneability of their electronic properties. For instance, the ability to create new electronic band structures in graphen...

Full description

Saved in:

Bibliographic Details
Main Authors:	Qu, Amy C, Nigge, Pascal, Link, Stefan, Levy, Giorgio, Michiardi, Matteo, Spandar, Parsa L, Matthé, Tiffany, Schneider, Michael, Zhdanovich, Sergey, Starke, Ulrich, Gutiérrez, Christopher, Damascelli, Andrea
Format:	Journal Article
Language:	English
Published:	23-04-2022
Subjects:	Physics - Materials Science Physics - Mesoscale and Nanoscale Physics Physics - Quantum Physics Physics - Strongly Correlated Electrons
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Science Advances, 8, eabm5180 (2022) Two-dimensional quantum materials offer a robust platform for investigating the emergence of symmetry-broken ordered phases owing to the high tuneability of their electronic properties. For instance, the ability to create new electronic band structures in graphene through moir\'e superlattices from stacked and twisted structures has led to the discovery of several correlated and topological phases. Here we report an alternative method to induce an incipient symmetry-broken phase in graphene at the millimetre scale. We show that an extremely dilute concentration ($<\!0.3\% $) of surface adatoms can self-assemble and trigger the collapse of the graphene atomic lattice into a distinct Kekul\'e bond density wave phase, whereby the carbon C-C bond symmetry is broken globally. Using complementary momentum-resolved techniques such as angle-resolved photoemission spectroscopy (ARPES) and low-energy electron diffraction (LEED), we directly probe the presence of this density wave phase and confirm the opening of an energy gap at the Dirac point. We further show that this Kekul\'e density wave phase occurs for various Fermi surface sizes and shapes, suggesting that this lattice instability is driven by strong electron-lattice interactions. Our results demonstrate that dilute concentrations of self-assembled adsorbed atoms offer an attractive alternative route towards designing novel quantum phases in two-dimensional materials.
DOI:	10.48550/arxiv.2204.10999