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Title: Imaging chiral symmetry breaking from Kekule bond order in graphene

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. Furthermore, 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.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ; ORCiD logo [4] ; ORCiD logo [2] ;  [5] ;  [5] ;  [1]
  1. Columbia Univ., New York, NY (United States)
  2. Cornell Univ., Ithaca, NY (United States)
  3. State Univ. of New York (SUNY), New York, NY (United States)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Cornell Univ., Ithaca, NY (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Nature Physics
Additional Journal Information:
Journal Volume: 12; Journal Issue: 10; Journal ID: ISSN 1745-2473
Publisher:
Nature Publishing Group (NPG)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1360195