摘要
Understanding the interplay between superconductivity and charge-density wave(CDW)in NbSe_(2) is vital for both fundamental physics and future device applications.Here,combining scanning tunneling microscopy,angleresolved photoemission spectroscopy and Raman spectroscopy,we study the CDW phase in the monolayer NbSe_(2) films grown on various substrates of bilayer graphene(BLG),SrTiO_(3)(111),and Al_(2)O_(3)(0001).It is found that the two stable CDW states of monolayer NbSe_(2) can coexist on NbSe2/BLG surface at liquid-nitrogen temperature.For the NbSe_(2)/SrTiO_(3)(111)sample,the unidirectional CDW regions own the kinks at±41 meV and a wider gap at 4.2 K.It is revealed that the charge transfer from the substrates to the grown films will influence the configurations of the Fermi surface,and induce a 130 meV lift-up of the Fermi level with a shrink of the Fermi pockets in NbSe_(2)/SrTiO_(3)(111)compared with the NbSe2/BLG.Combining the temperature-dependent Raman experiments,we suggest that the electron-phonon coupling in monolayer NbSe2 dominates its CDW phase transition.
基金
Supported by the National Natural Science Foundation of China (Grant Nos. 11774154, 11790311, and 12004172)
the National Key Research and Development Program of China (Grant No. 2018YFA0306800)
the Fundamental Research Funds for the Central Universities (Grant No. 0204-14380186)
the Jiangsu Planned Projects for Postdoctoral Research Funds (Grant No. 2020Z172)
the Program for High-Level Entrepreneurial and Innovative Talents Introduction of Jiangsu Province
the Program B for Outstanding Ph.D. Candidates of Nanjing University
