Time-dependent magnetization of a superconducting glass

The time dependence of the magnetization of polycrystalline samples of the high-temperature superconductor ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ has been investigated in order to ascertain the limits of the glasslike state. Slow rates of decay have been found to persist and to continuously decrease with increasing temperature up to the superconducting transition, suggesting that the latter is the upper bound on glasslike behavior.