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Nat Mater. 2016 Aug;15(8):840-4. doi: 10.1038/nmat4653. Epub 2016 May 30.

Soliton-dependent plasmon reflection at bilayer graphene domain walls.

Author information

1
Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
2
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
3
Physics Department, Tsinghua University, Beijing 100084, China.
4
Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
5
Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

Abstract

Layer-stacking domain walls in bilayer graphene are emerging as a fascinating one-dimensional system that features stacking solitons structurally and quantum valley Hall boundary states electronically. The interactions between electrons in the 2D graphene domains and the one-dimensional domain-wall solitons can lead to further new quantum phenomena. Domain-wall solitons of varied local structures exist along different crystallographic orientations, which can exhibit distinct electrical, mechanical and optical properties. Here we report soliton-dependent 2D graphene plasmon reflection at different 1D domain-wall solitons in bilayer graphene using near-field infrared nanoscopy. We observe various domain-wall structures in mechanically exfoliated graphene bilayers, including network-forming triangular lattices, individual straight or bent lines, and even closed circles. The near-field infrared contrast of domain-wall solitons arises from plasmon reflection at domain walls, and exhibits markedly different behaviours at the tensile- and shear-type domain-wall solitons. In addition, the plasmon reflection at domain walls exhibits a peculiar dependence on electrostatic gating. Our study demonstrates the unusual and tunable coupling between 2D graphene plasmons and domain-wall solitons.

PMID:
27240109
DOI:
10.1038/nmat4653

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