NMR studies of overdoped Y1xCaxBa2Cu3O7δ

Abstract
89YNMR and 17ONMR data from overdoped Y1xCaxBa2Cu3O7δ superconductors is presented and interpreted in terms of a peak in the density of states (DOS) that is pinned to the Fermi level and grows with progressive overdoping. This is in contrast to the underdoped side where there occurs a gap in the DOS pinned to the Fermi level. The data, which may be common to the high-temperature superconducting cuprates, are inconsistent with previously proposed models of phase separation or an increasing density of local moments.