Two-dimensional honeycomb crystals have inspired intense research interest for their novel properties and great potential in electronics and optoelectronics. Here, through molecular beam epitaxy on SrTiO_3(001), we re...Two-dimensional honeycomb crystals have inspired intense research interest for their novel properties and great potential in electronics and optoelectronics. Here, through molecular beam epitaxy on SrTiO_3(001), we report successful epitaxial growth of metal-rich chalcogenide Fe_(2)Te, a honeycomb-structured film that has no direct bulk analogue, under Te-limited growth conditions. The structural morphology and electronic properties of Fe_(2)Te are explored with scanning tunneling microscopy and angle resolved photoemission spectroscopy, which reveal electronic bands cross the Fermi level and nearly flat bands. Moreover, we find a weak interfacial interaction between Fe_(2)Te and the underlying substrates, paving a newly developed alternative avenue for honeycomb-based electronic devices.展开更多
The Mn-Bi-Te class of compounds are recently discovered topological insulators with broken time-reversal-symmetry,which host unique quantum anomalous Hall and axion insulator states.Their key characteristics are belie...The Mn-Bi-Te class of compounds are recently discovered topological insulators with broken time-reversal-symmetry,which host unique quantum anomalous Hall and axion insulator states.Their key characteristics are believed to be sufficiently understood by models in a single-particle picture.Here,we apply scanning tunneling microscopy to study the electronic properties of MnBi_(2)Te_(4)and MnBi_(4)Te_(7).Unexpectedly,our quasiparticle interference(QPI)results demonstrate that rotational symmetry of the crystal breaks,i.e.a nematic-like pattern arises,in certain energy range but persists in others.Moreover,our data in the presence of an external magnetic field rule out the possibility of the material magnetism as an origin of the C2 symmetric QPI pattern.This study reveals that the interaction in the Mn-Bi-Te class of topological materials may play an essential role in their electronic states,and thus opens a new path for investigating the interplay between wavefunction topology and symmetry breaking phases.展开更多
Intercalation is an effective method to modify physical properties and induce novel electronic states of transition metal dichalcogenide(TMD)materials.However,it is difficult to reveal the microscopic electronic state...Intercalation is an effective method to modify physical properties and induce novel electronic states of transition metal dichalcogenide(TMD)materials.However,it is difficult to reveal the microscopic electronic state evolution in the intercalated TMDs.Here we successfully synthesize the copper-intercalated 1T-TaS_(2) and characterize the structural and electronic modification combining resistivity measurements,atomic-resolution scanning transmission electron microscopy(ADF-STEM),and scanning tunneling microscopy(STM).The intercalated Cu atom is determined to be directly below the Ta atom and suppresses the commensurate charge density wave(CCDW)phase.Two specific electronic modulations are discovered in the near-commensurate(NC)CDW phase:the electron doping state near the defective star of Davids(SDs)in metallic domains and the spatial evolution of the Mott gap in insulating domains.Both modulations reveal that intercalated Cu atoms act as a medium to enhance the interaction between intralayer SDs,in addition to the general charge transfer effect.It also solidifies the Mott foundation of the insulating gap in pristine samples.The intriguing electronic evolution in Cu-intercalated 1T-TaS_(2) will motivate further exploration of novel electronic states in the intercalated TMD materials.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 51788104, 11604366, 11774192, and 11634007)the National Key R&D Program of China (Grant Nos. 2017YFA0304600 and 2018YFA0305603)。
文摘Two-dimensional honeycomb crystals have inspired intense research interest for their novel properties and great potential in electronics and optoelectronics. Here, through molecular beam epitaxy on SrTiO_3(001), we report successful epitaxial growth of metal-rich chalcogenide Fe_(2)Te, a honeycomb-structured film that has no direct bulk analogue, under Te-limited growth conditions. The structural morphology and electronic properties of Fe_(2)Te are explored with scanning tunneling microscopy and angle resolved photoemission spectroscopy, which reveal electronic bands cross the Fermi level and nearly flat bands. Moreover, we find a weak interfacial interaction between Fe_(2)Te and the underlying substrates, paving a newly developed alternative avenue for honeycomb-based electronic devices.
基金the NSFC(Grants No.11790313,No.92065201,No.11874256,No.11874258,No.12074247,No.12174252,No.11861161003,No.12025404,No.11904165,No.92161201,No.12104221,and No.12074181)Ministry of Science and Technology of China(Grants No.2019YFA0308600,2020YFA0309000,2017YFA0303203)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)the Science and Technology Commission of Shanghai Municipality(Grants No.2019SHZDZX01,No.19JC1412701,No.20QA1405100)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20200312,BK20200310,and BK20190286)or partial support.F.S.Li also acknowledge financial support from the Suzhou Science and Technology Program(Grant No.SJC2021009)and the Youth Innovation Promotion Association of Chinese Academy of Sciences(2017370).
文摘The Mn-Bi-Te class of compounds are recently discovered topological insulators with broken time-reversal-symmetry,which host unique quantum anomalous Hall and axion insulator states.Their key characteristics are believed to be sufficiently understood by models in a single-particle picture.Here,we apply scanning tunneling microscopy to study the electronic properties of MnBi_(2)Te_(4)and MnBi_(4)Te_(7).Unexpectedly,our quasiparticle interference(QPI)results demonstrate that rotational symmetry of the crystal breaks,i.e.a nematic-like pattern arises,in certain energy range but persists in others.Moreover,our data in the presence of an external magnetic field rule out the possibility of the material magnetism as an origin of the C2 symmetric QPI pattern.This study reveals that the interaction in the Mn-Bi-Te class of topological materials may play an essential role in their electronic states,and thus opens a new path for investigating the interplay between wavefunction topology and symmetry breaking phases.
基金supported by the National Natural Science Foundation of China(U1832202,11888101,11920101005,12141402,and 12274459)the Chinese Academy of Sciences(QYZDB-SSW-SLH043,XDB33020100,and XDB28000000)+4 种基金the Beijing Municipal Science and Technology Commission(Z171100002017018,and Z200005)the National Key R&D Program of China(2018YFE0202600,2022YFA1403100,and 2022YFA1403800)the Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China(RUC)(18XNLG14,19XNLG13,19XNLG17,and 20XNH062)the Synergic Extreme Condition User Facility,Beijing,ChinaBeijing National Laboratory for Condensed Matter Physics。
基金This work was supported by the National Key Research and Development Program(No.2019YFA0308602)the Key Research and Development Program of Zhejiang Province,China(No.2021C01002)+6 种基金Vacuum Interconnected Nanotech Workstation(Nano-X)(B2004)the Fundamental Research Funds for the Central Universities in ChinaD.D.and C.J.thank the National Natural Science Foundation of China(Nos.NSFC-51772265 and NSFC-61721005)J.G.,W.W.,X.L.,W.L.,and Y.S.thank the support of the National Key Research and Development Program(No.2016YFA0300404)the National Natural Science Foundation of China(Nos.NSFC-11674326 and NSFC-11874357)the Joint Funds of the National Natural Science Foundation of Chinathe Chinese Academy of Sciences’Large-scale Scientific Facility(Nos.U1832141,U1932217,and U2032215).
文摘Intercalation is an effective method to modify physical properties and induce novel electronic states of transition metal dichalcogenide(TMD)materials.However,it is difficult to reveal the microscopic electronic state evolution in the intercalated TMDs.Here we successfully synthesize the copper-intercalated 1T-TaS_(2) and characterize the structural and electronic modification combining resistivity measurements,atomic-resolution scanning transmission electron microscopy(ADF-STEM),and scanning tunneling microscopy(STM).The intercalated Cu atom is determined to be directly below the Ta atom and suppresses the commensurate charge density wave(CCDW)phase.Two specific electronic modulations are discovered in the near-commensurate(NC)CDW phase:the electron doping state near the defective star of Davids(SDs)in metallic domains and the spatial evolution of the Mott gap in insulating domains.Both modulations reveal that intercalated Cu atoms act as a medium to enhance the interaction between intralayer SDs,in addition to the general charge transfer effect.It also solidifies the Mott foundation of the insulating gap in pristine samples.The intriguing electronic evolution in Cu-intercalated 1T-TaS_(2) will motivate further exploration of novel electronic states in the intercalated TMD materials.
