Studies of Y-Ba-Cu-O single crystals by x-ray absorption spectroscopy

摘要

The symmetry and density of unoccupied states of YBa(sub 2)Cu(sub 3)O(sub 7) YBa(sub 2)Cu(sub 4)O(sub 8) have been investigated by orientation dependent x-ray absorption spectroscopy on the O 1s edge using a bulk-sensitive fluorescence-yield-detection method. It has been found that the O 2p holes are distributed equally between the CuO(sub 2) planes and CuO chains and that the partial density of unoccupied O 2p states in the CuO(sub 2) planes are identical in both systems investigated. The upper Hubbard band has been observed in the planes but not in the chains in both systems. 18 refs.