Superconducting and Magnetic Properties in Metamorphic Phases of GdBa₂Cu₃O_7-δ

Abstract

Superconducting and magnetic properties were studied on samples of GdBa 2 Cu 3 O 7-δ in the ortho-I, ortho-II and tetra-II phases, where ortho-I is typical of the 90 K-superconductor. The ortho-I sample shows a value of T c =92.7±0.3 K and the Meissner flux expulsion near 100% at T =79.0 K. Ortho-II has a value of T c =49.0±5.0 K, while tetra-II shows no superconductivity until 4.2 K. The susceptibility data for ortho-I between 100 and 700 K provides the effective magnetic moment 7.38µ B , which is slightly smaller than 7.94µ B for a free trivalent ion of Gd.