Evolution of vortex structure of two-level granular high temperature superconductor YBa2Cu3O7-δ under influence of temperature, magnetic field, and transport current

摘要

The measurements of temperature dependences of electrical resistivity of granular high temperature superconductor (HTS) YBa₂Cu₃O_7-δ ρ(T) at different values of external magnetic field 0 ≤ H_ext ≤ 100 Oe in the range of temperatures from the temperature of resistivity appearance T_ρ=0 to critical temperature of superconducting transition are carried out at transport current density j = 50 - 2000 mA/cm2. The influence of temperature, external magnetic field and transport current density on kinetics of phase transitions in both subsystems of the granular HTS was investigated. The possibility of passing the Berezinskii-Kosterlitz-Thouless transition (BKT - transition) in the Josephson medium is established. The conditions at which such topological phase transition is observed are studied.