Electronic States of Graphene Grain Boundaries

Abstract

We introduce a model for amorphous grain boundaries in graphene, and find that stable structures can exist along the boundary that are responsible for local density of states enhancements both at zero and finite (~0.5 eV) energies. Such zero energy peaks in particular were identified in STS measurements [J. Červenka, M. I. Katsnelson, and C. F. J. Flipse, Nature Physics 5, 840 (2009)], but are not present in the simplest pentagon-heptagon dislocation array model [O. V. Yazyev and S. G. Louie, Physical Review B 81, 195420 (2010)]. We consider the low energy continuum theory of arrays of dislocations in graphene and show that it predicts localized zero energy states. Since the continuum theory is based on an idealized lattice scale physics it is a priori not literally applicable. However, we identify stable dislocation cores, different from the pentagon-heptagon pairs, that do carry zero energy states. These might be responsible for the enhanced magnetism seen experimentally at graphite grain boundaries.

10 pages, 4 figures, submitted to Physical Review B

References in corpus (12)

• Half-Metallic Graphene Nanoribbons
• Topological Defects in Graphene: Dislocations and Grain Boundaries
• Room-temperature ferromagnetism in graphite driven by 2D networks of point defects
• Disorder Induced Localized States in Graphene
• Vacancy induced magnetism in graphene and graphene ribbons
• Magnetic moments in the presence of topological defects in graphene
• Low energy excitations in graphite: The role of dimensionality and lattice defects
• Dislocations in graphene
• Interactions and magnetism in graphene boundary states
• Grain boundary energies and cohesive strength as a function of geometry
• An Index Theorem for Graphene
• On the Dirac and Pauli operators with several Aharonov-Bohm solenoids