ELECTRONIC-PROPERTIES OF ELECTRON-DOPED ND2-XCEXCUO4-DELTA, SR1-XNDXCUO2-DELTA, AND HOLE-DOPED ND1.4CE0.2SR0.4CUO4-DELTA STUDIED BY PHOTOELECTRON-SPECTROSCOPY

We present investigations on the electronic structure of the recently discovered, electron-doped infinite-layer compound Sr1-xNdxCuO2-delta (T(c) almost-equal-to 40 K) by means of photoelectron spectroscopy wit h synchrotron radiation. This system is compared with the two closely related cuprates Nd2-xCeCuO4-delta (electron doped) and Ndl.4Ce0.2Sr0. 4CuO4-delta (hole doped). Valence band spectra in the Cu 3p-->3d reson ance are interpreted in terms Of CuO4 (n-doped compounds) and CuO5 (p- doped system) cluster models. From our calculations we find a consider ably higher Cu 3d Coulomb correlation for the electron-doped compounds as well as a very low Cu-O hybridization for the infinite-layer syste m. Partial Nd spectra of Sr0.85Nd0.15CuO2-delta show the Nd dopants to be trivalent, thus confirming the infinite-layer compound to be elect ron doped. Analysis of partial Nd valence bands and magnetic susceptib ilities of Nd2-xCexCuO4-delta and Nd1.4Ce0.2Sr0.4CuO4-delta gives very similar electronic parameters and antiferromagnetic correlations betw een Nd spins for both cuprates.