Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has b...Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has become particularly important.However,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation Facility.The beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 eV.In addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.展开更多
Graphene with a Dirac cone-like electronic structure has been extensively studied because of its novel transport properties and potential application for future electronic devices.For epitaxially grown graphene,the pr...Graphene with a Dirac cone-like electronic structure has been extensively studied because of its novel transport properties and potential application for future electronic devices.For epitaxially grown graphene,the process conditions and the microstructures are strongly dependent on various substrate materials with different lattice constants and interface energies.Utilizing angle-resolved photoemission spectroscopy,here we report an investigation of the electronic structure of single-crystalline graphene grown on Cu/Ni(111)alloy film by chemical vapor deposition.With a relatively low growth temperature,graphene on Cu/Ni(111)exhibits a Dirac cone-like dispersion comparable to that of graphene grown on Cu(111).The linear dispersions forming Dirac cone are as wide as 2 e V,with the Fermi velocity of approximately 1.1×10^6 m/s.Dirac cone opens a gap of approximately 152 meV at the binding energy of approximately 304 meV.Our findings would promote the study of engineering of graphene on different substrate materials.展开更多
Recently, 5d transition metal iridates have been reported as promising materials for the manttfacture of exotic quan- tum states. Apart from the semimetallic ground states that have been observed, perovskite SrlrO3 is...Recently, 5d transition metal iridates have been reported as promising materials for the manttfacture of exotic quan- tum states. Apart from the semimetallic ground states that have been observed, perovskite SrlrO3 is also predicted to have a lattice-symmetrically protected topological state in the （110） plane due to its strong： spin-orbil coupling and electron correlation. Compared with non-polar （001）-SflrO3, the especial polarity of （110）-SrIrC）3 undoubtedly adds the： difficulty of fabrication and largely impedes the research on its surface states. Here, we have successfully synthesized high-quality （110）-SflrO3 thin films on （110）-SrTiO3 substrates by reactive molecular beam epitaxy fi^r the first time. Both reflec- tion high-energy electron diffraction pattems and x-ray diffraction measurements suggest the expected orientation and outstanding crystallinity. A （1 × 2） surface reconstruction driven from the surface instabiJity, the. same as that reported in （110）-SrTiO3, is observed. The electric transport measurements uncover that （110）-SrIrO3 exhibits a more prominent semimetallic property in comparison to （001）-SrIrO3.展开更多
基金supported by the National Key R&D Program of the MOST of China(No.2016YFA0300204)the National Natural Science Foundation of China(No.11227902)as part of the SiP·ME2 beamline project。
文摘Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has become particularly important.However,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation Facility.The beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 eV.In addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51772317,11604356,and 11704394)
文摘Graphene with a Dirac cone-like electronic structure has been extensively studied because of its novel transport properties and potential application for future electronic devices.For epitaxially grown graphene,the process conditions and the microstructures are strongly dependent on various substrate materials with different lattice constants and interface energies.Utilizing angle-resolved photoemission spectroscopy,here we report an investigation of the electronic structure of single-crystalline graphene grown on Cu/Ni(111)alloy film by chemical vapor deposition.With a relatively low growth temperature,graphene on Cu/Ni(111)exhibits a Dirac cone-like dispersion comparable to that of graphene grown on Cu(111).The linear dispersions forming Dirac cone are as wide as 2 e V,with the Fermi velocity of approximately 1.1×10^6 m/s.Dirac cone opens a gap of approximately 152 meV at the binding energy of approximately 304 meV.Our findings would promote the study of engineering of graphene on different substrate materials.
基金Project supported by the National Key Research and Development Program of the MOST of China(Grant No.2016YFA0300204)the National Key Basic Research Program of China(Grant No.2015CB654901)+2 种基金the National Natural Science Foundation of China(Grant Nos.11574337,11227902,11474147,and11704394)Shanghai Sailing Program(Grant No.17YF1422900)the Award for Outstanding Member in Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘Recently, 5d transition metal iridates have been reported as promising materials for the manttfacture of exotic quan- tum states. Apart from the semimetallic ground states that have been observed, perovskite SrlrO3 is also predicted to have a lattice-symmetrically protected topological state in the （110） plane due to its strong： spin-orbil coupling and electron correlation. Compared with non-polar （001）-SflrO3, the especial polarity of （110）-SrIrC）3 undoubtedly adds the： difficulty of fabrication and largely impedes the research on its surface states. Here, we have successfully synthesized high-quality （110）-SflrO3 thin films on （110）-SrTiO3 substrates by reactive molecular beam epitaxy fi^r the first time. Both reflec- tion high-energy electron diffraction pattems and x-ray diffraction measurements suggest the expected orientation and outstanding crystallinity. A （1 × 2） surface reconstruction driven from the surface instabiJity, the. same as that reported in （110）-SrTiO3, is observed. The electric transport measurements uncover that （110）-SrIrO3 exhibits a more prominent semimetallic property in comparison to （001）-SrIrO3.
