Irreversible Characteristics of Melt Processed Sm-123 Superconductor



                                               E. S. Otabe  , T. Matsushita;
           Department of Computer Science and Electronics, Kyushu Institute of Technology,

                                          680-4 Kawazu, Iizuka 820-8502, Japan
                 Graduate School of Information Science and Electrical Engineering (ISEE),

               Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan



    The  DC  magnetization  and  its  relaxation  were  measured  using  a  SQUID  magnetometer  for

a melt processed Sm-123 superconductor and its critical current density,  irreversibility field and

apparent pinning potential were estimated.  Nominal composition of 123- and 211-phases of the

specimen was 3:1 and Ag of 20 wt% was included.  The observed peak effect in the critical current

density was not so significant.  It has been considered that such a peak effect is caused by the field

induced pinning interaction in substituted phase with lower Tc.  This mechanism is considered to be

a repulsive interaction through the kinetic energy under the influence of proximity effect.  Hence,

the suppression of the peak effect will be ascribed to an interference between this interaction and

the attractive core pinning interaction in 211 phase.  The observed irreversible characteristics are

compared with analytical results using the flux creep theory and good agreements are obtained.

The scaling of the pinning force density is also discussed.

    The authors thank to Dr.  Morita of Nippon Steel for preparation of the Sm-123 specimen.