溶融法によるYBa₂Cu₃O_yの磁化応答

抄録

We measured the magnetization curve of a melt-processed YBa₂Cu₃O_y in the temperature region 20-60 K. Measurements were carried out by the use of a SQUID, where the applied field ranges 0-1 T. The observed curves were analyzed in the framework of the Kim-Anderson model for critical current density, where the critical current density Jc is expressed as a function of the localized flux density Bi in the sample, Jc=k/(BO+|Bi|). Here k designates the pinning force and B0 is a temperaturedependent parameter. By taking into consideration the demagnetization effect, the experimental results were reproduced very well, suggesting that the Kim-Anderson model is quite useful for the study of the magnetic response of the specimen. Some discussion on the temperature-dependent parameters involved in the model are given.