Polarization-dependent soft X-ray absorption of over-doped superconducting Sr2CuO3+δ single crystal

In order to study the factors affecting superconductivity of Sr2CuO3+delta, polarized X-ray absorption spectra (XAS) were measured at Cu L-23 edge and O K edge of an over-doped single crystal specimen. This polarized XAS study reveals a distinctive anisotropic local electronic structure of Cu coordination: the unoccupied states are dominated by the in-plane components of Cu 3d(x2-y2) and O 2p(x,y). However, the signal from the unoccupied out-of-plane O 2p(z) and Cu 3d(z2) states also appear. Furthermore, the detailed analysis of Cu L-3-edge XAS at 300K and 17.3 K indicates that the conductive carrier partly shifts from out-of-plane to in-plane in the superconducting state. Theoretical calculation of Cu L-23-edge core level spectra based on Charge Transfer Multiplet theory is fairly consistent with above experimental results. (C) 2014 Elsevier B.V. All rights reserved.