Quantum creep of Josephson intergrain vortices in Bi2Sr2Ca2Cu3O10

Abstract

Magnetic relaxation caused by the creep of Josephson intergrain vortices is studied in Bi2Sr2Ca2Cu3010 high-T c superconductor in (Physica C 222 (1994) 149). PACS numbers: 74.60.Ge, 74.80.Bj, 74.72.Hs Recently, it was shown by various groups that the classical thermally activated creep of Abrikosov vortices in high-T c superconductors (HTS) is changed to a quantum creep with lowering temperature 1. The experimental results could be well understood within the quantum collective creep theory in the limit of strong dissipation 2 or Hall tunneling theory 3. On the other hand, the phenomenon of macroscopic quantum tunneling (MQT) occurring in Josephson junctions systems such as the superconducting quantum interference device (SQUID) or Josephson-junctions arrays has always attracted a great experimental 4-6 and theoretical 7-10 interest. To our best knowledge, however, there are no reports on MQT occurring either in artificially grown HTS-based Josephson junctions or in the Josephson medium of polycrystalline HTS.The investigation of a possible quantum tunneling of Josephson intergrain vortices in HTS ceramics is the subject of the present work.We have studied the magnetic relaxation caused by the creep of Josephson intergrain vortices in Bi2Sr2Ca2Cu3010 (Bi: 2223) polycrystalline sample, and found that at high enough temperatures the normalized logarithmic 207 0022-2291/97/0200-0207512.50/0 9 1997 Plenum Publishing Corporation