Electronic Structure of Nd_<2-x>Ce_xCuO_4 and La_<2-x>Sr_xCuO_4 Deduced from Cu 2p Photoemission and Photoabsorption(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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The electronic structures of Nd_<2-x>Ce_xCuO_4 and La_<2-x>Sr_xCuO_4 are studied using numerical diagonalization calculations for cluster models, Cu_5O_<16>, Cu_7O_<20>, and Cu_8O_<16>. The Fermi energy of Nd_2CuO_4 used in the experiment is assumed to be pinned at the bottom of the upper Hubbard band, while that of La_2CuO_4 is assumed to be pinned at the top of the Zhang-Rice singlet band. This assumption enables us to consistently understand the doping dependence of the Cu 2p photoemission and photoabsorption spectra in Nd_<2-x>Ce_xCuO_4 and La_<2-x>Sr_xCuO_4 on the basis of the so-called "crossing the gap" picture. The present calculation of Cu 2p photoemission spectrum also shows that core hole screening caused by charge transfer between neighboring CuO_4 plaquettes, in other words, nonlocal screening (NLS), is important in Nd_2CuO_4 as well as in La_2CuO_4.
社団法人日本物理学会の論文
2009-03-15