Multimorphism and gap opening of charge-density-wave phases in monolayer VTe2  

作　　者：Meizhuang Liu Changwei Wu Zizhao Liu Zhiqiang Wang Dao-Xin Yao Dingyong Zhong 

机构地区：[1]School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-sen University,Guangzhou,510275,China

出　　处：《Nano Research》2020年第6期1733-1738,共6页纳米研究（英文版）

基　　金：D.Y.Z.thanks the financial support from the National Natural Science Foundation Program of China(Nos.11974431 and 11832019);the Guangzhou Science and Technology Project(No.201707020002);C.W.W.and D.X.Y.thank the support from The National Key Research and Development Program of China(Nos.2017YFA0206203 and 2018YFA0306001);the National Natural Science Foundation Program of China(No.11974432);Guangdong Basic and Applied Basic Research Foundation(No.2019A1515011337);Leading Talent Program of Guangdong Special Projects;The computation part of the work was supported by National Supercomputer Center in Guangzhou,China.

摘　　要：Vanadium dichalcogenides have attracted increasing interests for the charge density wave phenomena and possible ferromagnetism.Here,we report on the multiphase behavior and gap opening in monolayer VTe2 grown by molecular beam epitaxy.Scanning tunneling microscopy(STM)and spectroscopy study revealed the(4×4)metallic and gapped(2√3×2√3)charge-density wave(CDW)phases with an energy gap of≈40 meV.Through the in-plane condensation of vanadium atoms,the typical star-of-David clusters and truncated triangle-shaped clusters are formed in the(4×4)and(2√3×2√3)phases respectively,resulting in different surface morphologies and electronic structures as confirmed by density functional theory(DFT)calculations with on-site Coulomb repulsion.The CDW-driven reorganization of the atomic structure weakens the ferromagnetic superexchange coupling and strengthens the antiferromagnetic exchange coupling on the contrary,suppressing the long-range magnetic order in monolayer VTe2.The electron correlation is found to be important to explain the gap opening in the(2√3×2√3)phase.

关 键 词：transition-metal dichalcogenides charge density wave 1T-VTe2 scanning tunneling microscopy 

分 类 号：TQ13[化学工程—无机化工]