Oxygen nuclear magnetic resonance on the 90 K plateau of YBa2Cu3O7-δ

Abstract
We examine the body of 17O nuclear magnetic resonance (NMR) data obtained in samples of YBa2Cu3O7-δ with T c ≳ 90 K. We point out significant deviations from typical metallic behaviour, contrary to conventional characterizations of these data. Furthermore, there is a surprisingly strong sample-to-sample variation in the 17O NMR properties, given the narrow range of oxygen content. We suggest that this strong sample variability merits further study.