P07S

23BG012, 23BU010

BL-9A, IPES

Effects of Quantum Charge Fluctuations on the Electron
Self-energy of High–Tc Cuprate Superconductors Using
Angle-Resolved Photoemission and Inverse Photoemission
Spectroscopies
Y. Onishia, Y. Miyaia, Y. Tsubotaa, K. Tanakac, S. Ishidad, H. Eisakid,
H. Satob, M. Aritab, K. Shimadaa,b, and S. Idetaa,ba Graduate School of Advanced Science and Engineering, Hiroshima Univ., Higashi-Hiroshima 739-0046, Japanb Hiroshima Synchrotron Radiation Center (HiSOR), Hiroshima Univ., Higashi-Hiroshima 739-0046, Japanc UVSOR-Ⅲ

Synchrotron, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japand National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8560, Japan

Keywords: high- Tc superconductors, ARPES, IPES, charge fluctuations, electronic structure

In the previous studies of angle-resolved photoemission spectroscopy (ARPES), it has been reported thatkink structures are observed in the electronic structure for the cuprates likely due to spin fluctuations and/orphonons [1-3]. This observation indicates that the glue of the Cooper pair is magnons or phonons. On theother hand, in recent years, resonant inelastic x-ray scattering experiments have been performed in the holeand electron-doped high-Tc cuprate superconductors and charge excitations are observed [4 ,5]. In addition,
theoretical calculations of unconventional high-Tc superconductors using the layered t-J model, which
includes the long- and short-range Coulomb interactions with charge fluctuations, have been reported tostudy how charge fluctuations interact to the electronic structure in cuprates [6, 7]. However, the effect ofcharge fluctuations to the electronic structure of cuprates has not been studied by angle-resolved
photoemission spectroscopy (ARPES) directly.
In this study, to investigate the role of charge fluctuations for the electronic structure in the high-Tc cuprate
superconductor, Bi2Sr1.6La0.4CuO6+δ (Bi2201), we have performed ARPES and inverse photoemission
spectroscopy (IPES) to study the occupied and unoccupied states, respectively. In the experiments, ARPES
and IPES measurements are performed along high-symmetry lines in the Brillouin zone (Fig. 1, (a)). We
found the shoulder structure near 1 eV above the Fermi level in the IPES spectra as shown by red area in
Fig. 1 (b). In the poster presentation, we will show the details of the electronic structure on Bi2201 in theoccupied and unoccupied states and discuss the effect of charge fluctuations on the electronic structure ofhigh-Tc cuprate superconductors, including a comparison with theoretical calculations [6, 7].

(b)
(a)

FIGURE 1. (a) The Fermi-surface on the Brillouin zone for Bi2201. Each arrow corresponds to the arrow in the panel (b). (b)Energy-distribution curves in the second Brillouin zone (T = 13K, Ekin = 50eV).

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