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作者机构:Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Geballe Laboratory for Advanced Materials Departments of Physics and Applied Physics Stanford University Stanford California 94305 USA Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park California 94025 USA Electronics and Photonics Research Institute National Institute of Advanced Industrial Science and Technology Tsukuba Ibaraki 305-8558 Japan
出 版 物:《Physical Review B》 (Phys. Rev. B)
年 卷 期:2017年第96卷第24期
页 面:245112-245112页
核心收录:
基 金:Basic Energy Sciences, BES U.S. Department of Energy, USDOE Office of Science, SC Cornell University, CU Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF, (215132, P300P2151328) Division of Materials Sciences and Engineering, DMSE, (DE-AC02-76SF00515) Gordon and Betty Moore Foundation, GBMF, (GBMF4546)
主 题:Electronic structure High-temperature superconductors Strongly correlated systems Perturbation theory Photoemission spectroscopy
摘 要:We study optimally doped Bi2Sr2Ca0.92Y0.08Cu2O8+δ (Bi2212) using angle-resolved two-photon photoemission spectroscopy. Three spectral features are resolved near 1.5, 2.7, and 3.6 eV above the Fermi level. By tuning the photon energy, we determine that the 2.7-eV feature arises predominantly from unoccupied states. The 1.5- and 3.6-eV features reflect unoccupied states whose spectral intensities are strongly modulated by the corresponding occupied states. These unoccupied states are consistent with the prediction from a cluster perturbation theory based on the single-band Hubbard model. Through this comparison, a Coulomb interaction strength U of 2.7 eV is extracted. Our study complements equilibrium photoemission spectroscopy and provides a direct spectroscopic measurement of the unoccupied states in cuprates. The determined Coulomb U indicates that the charge-transfer gap of optimally doped Bi2212 is 1.1 eV.