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Visualizing the Anomalous Charge Density Wave States in Graphene/NbSe 2 Heterostructures
Author(s) -
Chen Yu,
Wu Lishu,
Xu Hai,
Cong Chunxiao,
Li Si,
Feng Shun,
Zhang Hongbo,
Zou Chenji,
Shang Jingzhi,
Yang Shengyuan A.,
Loh Kian Ping,
Huang Wei,
Yu Ting
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202003746
Subject(s) - charge density wave , condensed matter physics , graphene , materials science , heterojunction , raman spectroscopy , superconductivity , scanning tunneling microscope , ohmic contact , density of states , doping , nanotechnology , physics , optics , layer (electronics)
Metallic layered transition metal dichalcogenides (TMDs) host collective many‐body interactions, including the competing superconducting and charge density wave (CDW) states. Graphene is widely employed as a heteroepitaxial substrate for the growth of TMD layers and as an ohmic contact, where the graphene/TMD heterostructure is naturally formed. The presence of graphene can unpredictably influence the CDW order in 2D CDW conductors. This work reports the CDW transitions of 2H‐NbSe 2 layers in graphene/NbSe 2 heterostructures. The evolution of Raman spectra demonstrates that the CDW phase transition temperatures ( T CDW ) of NbSe 2 are dramatically decreased when capped by graphene. The induced anomalous short‐range CDW state is confirmed by scanning tunneling microscopy measurements. The findings propose a new criterion to determine the T CDW through monitoring the line shape of the A 1g mode. Meanwhile, the 2D band is also discovered as an indicator to observe the CDW transitions. First‐principles calculations imply that interfacial electron doping suppresses the CDW states by impeding the lattice distortion of 2H‐NbSe 2 . The extraordinary random CDW lattice suggests deep insight into the formation mechanism of many collective electronic states and possesses great potential in modulating multifunctional devices.