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Imaging chiral symmetry breaking from Kekulé bond order in graphene

Cornell Affiliated Author(s)

Author

Christopher Gutiérrez
C.-J. Kim
L. Brown
T. Schiros
D. Nordlund
E.B. Lochocki
K.M. Shen
J. Park
A.N. Pasupathy

Abstract

Chirality - or handedness' - is a symmetry property crucial to fields as diverse as biology, chemistry and high-energy physics. In graphene, chiral symmetry emerges naturally as a consequence of the carbon honeycomb lattice. This symmetry can be broken by interactions that couple electrons with opposite momenta in graphene. Here we directly visualize the formation of Kekulé bond order, one such phase of broken chiral symmetry, in an ultraflat graphene sheet grown epitaxially on a copper substrate. We show that its origin lies in the interactions between individual vacancies in the copper substrate that are mediated electronically by the graphene. We show that this interaction causes the bonds in graphene to distort, creating a phase with broken chiral symmetry. The Kekulé ordering is robust at ambient temperature and atmospheric conditions, indicating that intercalated atoms may be harnessed to drive graphene and other two-dimensional materials towards electronically desirable and exotic collective phases. © 2016 Macmillan Publishers Limited, part of Springer Natural. All rights reserved.

Date Published

Journal

Nature Physics

Volume

12

Issue

10

Number of Pages

950-958,

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987629925&doi=10.1038%2fnphys3776&partnerID=40&md5=de6aa73a566f4cd45090afe19fbe3070

DOI

10.1038/nphys3776

Group (Lab)

Kyle Shen Group

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