Evidence for Suppressed Screening on the Surface of High Temperature La2xSrxCuO4 and Nd2xCexCuO4 Superconductors

M. Taguchi, A. Chainani, K. Horiba, Y. Takata, M. Yabashi, K. Tamasaku, Y. Nishino, D. Miwa, T. Ishikawa, T. Takeuchi, K. Yamamoto, M. Matsunami, S. Shin, T. Yokoya, E. Ikenaga, K. Kobayashi, T. Mochiku, K. Hirata, J. Hori, K. Ishii, F. Nakamura, and T. Suzuki
Phys. Rev. Lett. 95, 177002 – Published 19 October 2005

Abstract

Hard x-ray photoemission spectroscopy (PES) of Cu core electronic states, with a probing depth of 60Å, is used to show that the Zhang-Rice singlet feature is present in La2CuO4 but is absent in Nd2CuO4. Hole and electron doping in La2xSrxCuO4 (LSCO) and Nd2xCexCuO4 (NCCO) result in new well-screened features which are missing in soft x-ray PES. Impurity Anderson model calculations establish screening from doped states as its origin, which is strongly suppressed within 15 Å of the surface. Complemented with x-ray absorption spectroscopy, the small chemical-potential shift in core levels (0.2eV) are shown to be consistent with modifications of valence and conduction band states spanning the band gap (1eV) upon hole and electron doping in LSCO and NCCO.

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  • Received 26 January 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.177002

©2005 American Physical Society

Authors & Affiliations

M. Taguchi1, A. Chainani1, K. Horiba1, Y. Takata1, M. Yabashi2,3, K. Tamasaku2, Y. Nishino2, D. Miwa2, T. Ishikawa2, T. Takeuchi1, K. Yamamoto1, M. Matsunami1, S. Shin1,4, T. Yokoya3, E. Ikenaga3, K. Kobayashi3, T. Mochiku5, K. Hirata5, J. Hori6, K. Ishii6, F. Nakamura6, and T. Suzuki6

  • 1Soft X-ray Spectroscopy Laboratory, RIKEN/SPring-8, Mikazuki, Mikazuki, Hyogo 679-5148, Japan
  • 2Coherent X-ray Optics Laboratory, RIKEN/SPring-8, Mikazuki, Mikazuki, Hyogo 679-5148, Japan
  • 3JASRI/SPring-8, Mikazuki, Mikazuki, Hyogo 679-5198, Japan
  • 4Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
  • 5Superconducting Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
  • 6Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan

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Vol. 95, Iss. 17 — 21 October 2005

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