title: Soliton-dependent plasmon reflection at bilayer graphene domain walls.
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.
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.|Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Zeng
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Ji-Hun
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Trinity
authors.initials: T
authors.lastname: Joshi
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Chenhao
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Long
authors.initials: L
authors.lastname: Ju
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: Jonghwan
authors.initials: J
authors.lastname: Kim
authors.affiliation: Physics Department, Tsinghua University, Beijing 100084, China.
authors.forename: Tairu
authors.initials: T
authors.lastname: Lyu
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.|Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Yuen-Ron
authors.initials: YR
authors.lastname: Shen
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.|Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Crommie
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Hong-Jun
authors.initials: HJ
authors.lastname: Gao
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.|Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang