Magnetic relaxation effects in YBa₂Cu₃O_7-δ thin films

The time relaxation of the magnetization of YBa2Cu3O7-δ thin films has been investigated. The slow nonexponential decay rates measured in the field-cooled (FC) and zero-field-cooled (ZFC) conditions show the same temperature dependence and vanish at Tc. Our data suggest that flux creep is important below 60 K and might be dominated by glass effects close to Tc. © 1988.