title: Cooperative Electron-Phonon Coupling and Buckled Structure in Germanene on Au(111).
abstract: Germanene, a single-atom-thick germanium nanosheet in a honeycomb lattice, was proposed to be a Dirac fermion material beyond graphene. We performed scanning tunneling microscopy and in situ Raman spectroscopy studies combined with first-principles calculations on the atomic structures and the electronic and phonon properties of germanene on Au(111). The low-buckled 1 × 1 germanene honeycomb lattice was determined to exist in an unexpected rectangular √7 × √7 superstructure. Through in situ Raman measurements, distinctive vibrational phonon modes were discovered in √7 × √7 germanene, revealing the special coupling between the Dirac fermion and lattice vibrations, namely, electron-phonon coupling (EPC). The significant enhancement of EPC is correlated with the tensile strain, which is evoked by the singular buckled structure of √7 × √7 germanene on the Au(111) substrate. Our results present clear evidence for the existence of epitaxial germanene and elucidate the exotic properties of germanene on Au(111).
authors.affiliation: Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong , Wollongong, NSW 2525, Australia.
authors.forename: Jincheng
authors.initials: J
authors.lastname: Zhuang
authors.affiliation: Key Laboratory of Materials Modification by Laser, Ion and Electron Beams ( Dalian University of Technology ), Ministry of Education, Dalian 116024, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Gao
authors.affiliation: Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong , Wollongong, NSW 2525, Australia.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong , Wollongong, NSW 2525, Australia.|UOW-BUAA Joint Research Centre, University of Wollongong , Wollongong, NSW 2525, Australia.
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Jiaou
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Materials Modification by Laser, Ion and Electron Beams ( Dalian University of Technology ), Ministry of Education, Dalian 116024, China.
authors.forename: Jijun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong , Wollongong, NSW 2525, Australia.|UOW-BUAA Joint Research Centre, University of Wollongong , Wollongong, NSW 2525, Australia.
authors.forename: Shi Xue
authors.initials: SX
authors.lastname: Dou
authors.affiliation: Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong , Wollongong, NSW 2525, Australia.|UOW-BUAA Joint Research Centre, University of Wollongong , Wollongong, NSW 2525, Australia.
authors.forename: Yi
authors.identifier: 0000-0003-1932-6732
authors.initials: Y
authors.lastname: Du
keywords: Raman; STM; electron−phonon coupling; germanene