Remanent moment of high-temperature superconductors: Implications for flux-pinning and glassy models

Superconducting quantum interference device (SQUID) magnetometer data on a variety of ceramics and crystals of Y-Ba-Cu-O show a remanent moment which accurately equals the difference of the field-cooled and zero-field-cooled moments in the low-field, low-temperature range. This effect is argued to point to a flux pinning rather than a superconductive glass model, particularly for the crystals. This holds true even when the glassy model is extended to include screening effects.