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论文类型： 期刊论文

发表时间： 2017-04-01

发表刊物： ACS NANO

收录刊物： SCIE、EI、PubMed

卷号： 11

期号： 4

页面范围： 3553-3559

ISSN号： 1936-0851

关键字： germanene; electron-phonon coupling; Raman; STM

摘要： 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 X 1 germanene honeycomb lattice was determined to exist in an unexpected rectangular root 7 X root 7 superstructure. Through in situ Raman measurements, distinctive vibrational phonon modes were discovered in root 7 X root 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 root 7 X root 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).