TIME-DEPENDENCE OF THE MAGNETIZATION OF BI2SR2CACU2O8 DISPLAYING THE PARAMAGNETIC MEISSNER EFFECT

The time dependence of the magnetization of a Bi2Sr2CaCu2O8 sample dis playing the paramagnetic Meissner effect has been studied as a functio n of field, temperature, and age of the system using superconducting q uantum interference device magnetometry. The field-cooled magnetizatio n is found to increase with time at low fields, while at higher fields the relaxation is negative. The zero-field-cooled relaxation shows an anomalous field dependence at low magnetic fields. The age of the sys tem does not yield an observable influence on the time dependence of t he magnetization. The results are discussed in terms of a model based on so called pi junctions.