Twisted bilayer graphene heterostructures have recently emerged as a well-established platform for studying strongly correlated phases,such as correlated insulating,superconducting,and topological states.Extending thi...Twisted bilayer graphene heterostructures have recently emerged as a well-established platform for studying strongly correlated phases,such as correlated insulating,superconducting,and topological states.Extending this notion to twisted multilayer graphene heterostructures has exhibited more diverse correlated phases,as some fundamental properties related to symmetry and band structures are correspondingly modified.Here,we report the observations of correlated states in twisted monolayer-trilayer(Bernal stacked)graphene heterostructures.Correlated phases at integer fillings of the moire unit cell are revealed at a high displacement field and stabilized with a moderate magnetic field on the electron-doping side at a twist angle of 1.45°,where the lift of degeneracy at the integer fillings is observed in the Landau fan diagram.Our results demonstrate the effectiveness of moire engineering in an extended structure and provide insights into electric-field tunable correlated phases.展开更多
The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density funct...The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM experiments find that pentacene adopts a highly selective and dispersed growth mode in the initial stage. By using DFT calculations including van der Waals interactions, we find that the configuration with pentacene adsorbed on face-centered cubic （fcc） regions of G/Ru is the most stable one, which accounts for the selective adsorption at low coverage. Moreover, at high coverage, we have successfully controlled the molecular assembly from amorphous, local ordering, to long-range order by optimizing the deposition rate and substrate temperature.展开更多
The formation of densely packed overlayer of iron phthalocyanine （FePc） molecules on single-layer graphene （SLG） epitaxially grown on Ru（0001） is studied by means of low temperature scanning tunneling microscopy...The formation of densely packed overlayer of iron phthalocyanine （FePc） molecules on single-layer graphene （SLG） epitaxially grown on Ru（0001） is studied by means of low temperature scanning tunneling microscopy. We show that the FePc molecules form single molecular arrays, ordered honeycomb lattice, Kagome lattice and square lattice with increasing molecular coverage. The densely packed square lattice of the molecular layer is modulated by the moire pattern of SLGJRu（O001）. The superposition of the square lattice of the molecular layer on the hexagonal lattice of SLG molte pattern leads to the formation of a larger strip moire pattern. This coverage-dependent self-assembling behavior of FePc on SLG/Ru（0001 ） is mainly driven by the inhomogeneous electronic structure of graphene moire oattern, due to soatial-deoendent interracial charge transfer between SLG and Ru（0001 ） substrate.展开更多
基金the National Key R&D Program of China(Grant No.2019YFA0307800,J.M.)Beijing Natural Science Foundation(Grant No.Z190011,J.M.)+1 种基金the National Natural Science Foundation of China(Grant Nos.11974347,J.M.and 12204479,Z.Z.)Fundamental Research Funds for the Central Universities(J.M.)。
文摘Twisted bilayer graphene heterostructures have recently emerged as a well-established platform for studying strongly correlated phases,such as correlated insulating,superconducting,and topological states.Extending this notion to twisted multilayer graphene heterostructures has exhibited more diverse correlated phases,as some fundamental properties related to symmetry and band structures are correspondingly modified.Here,we report the observations of correlated states in twisted monolayer-trilayer(Bernal stacked)graphene heterostructures.Correlated phases at integer fillings of the moire unit cell are revealed at a high displacement field and stabilized with a moderate magnetic field on the electron-doping side at a twist angle of 1.45°,where the lift of degeneracy at the integer fillings is observed in the Landau fan diagram.Our results demonstrate the effectiveness of moire engineering in an extended structure and provide insights into electric-field tunable correlated phases.
基金This work was financially supported by the Ministry of Science and Technology （MOST Nos. 2011CB921702 and 2011CB932700）, National Natural Science Foundation of China （NSFC No. 61222112）, Multilevel Molecular Assemblies： Structure, Dynamics, and Functions （TRR61）, Shanghai Supercomputer Center （SSC）, and Chinese Academy of Sciences （CAS） in China. WAH acknowledges support from the UK Car-Parinello consortium, grant No. EP/F037783/1.
文摘The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM experiments find that pentacene adopts a highly selective and dispersed growth mode in the initial stage. By using DFT calculations including van der Waals interactions, we find that the configuration with pentacene adsorbed on face-centered cubic （fcc） regions of G/Ru is the most stable one, which accounts for the selective adsorption at low coverage. Moreover, at high coverage, we have successfully controlled the molecular assembly from amorphous, local ordering, to long-range order by optimizing the deposition rate and substrate temperature.
基金We acknowledge the financial support from the National Natural Science Foundation of China （Nos. 61390501, 61622116 and 61471337）, the Chinese Academy of Sciences （Nos. XDPB0601 and XDPB0801） and the CAS Pioneer Hundred Talents Program. Y. Y. Z. would also thank Beijing Nova Program （No. Z181100006218023）. A portion of the research was performed in CAS Key Laboratory of Vacuum Physics.
基金Financial support from the National Natural Science Foundation of China(No. 51661135026)Ministry of Science and Technology of China(Nos. 2015CB921103, 2016YFA0300904)the Chinese Academy of Sciences
文摘The formation of densely packed overlayer of iron phthalocyanine （FePc） molecules on single-layer graphene （SLG） epitaxially grown on Ru（0001） is studied by means of low temperature scanning tunneling microscopy. We show that the FePc molecules form single molecular arrays, ordered honeycomb lattice, Kagome lattice and square lattice with increasing molecular coverage. The densely packed square lattice of the molecular layer is modulated by the moire pattern of SLGJRu（O001）. The superposition of the square lattice of the molecular layer on the hexagonal lattice of SLG molte pattern leads to the formation of a larger strip moire pattern. This coverage-dependent self-assembling behavior of FePc on SLG/Ru（0001 ） is mainly driven by the inhomogeneous electronic structure of graphene moire oattern, due to soatial-deoendent interracial charge transfer between SLG and Ru（0001 ） substrate.
