Magnetic Instability in High-J_c Y₁Ba₂Cu₃O₇ Prepared by Quench-Melt-Growth Process

Abstract

Magnetisation measurements of quench-melt-growth-processed Y 1 Ba 2 Cu 3 O 7 were performed in high fields of up to 23 T at 4.2 K by a sample extraction method. Many flux jumps were observed in the magnetization curve. It was demonstrated that high- T c oxide superconductors with very large J c of 10 7 A/cm 2 in fields at 4.2 K gave rise to magnetic instability due to the low specific heat.