Влияние температуры, внешнего магнитного поля и транспортного тока на электрофизические свойства, процессы эволюции вихревой структуры и фазовые переходы в подсистемах сверхпроводящих гранул и "слабых связей" гранулярного двухуровневого высокотемпературного сверхпроводника YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-delta-=/SUB=-

Abstract

AbstractThe temperature dependences of the resistivity of granular high-temperature superconductor YBa_2Cu_3O_7–δ ρ( T ) are measured at various transverse external magnetic fields 0 ≤ H _ext ≤ 100 Oe in the temperature range from the resistivity onset temperature T _ρ = 0 to the superconducting transition critical temperature T _ c at the transport current density from 50 to 2000 mA/cm^2. The effect of the external magnetic field and transport current density on the kinetics of phase transitions in both subsystems of granular two-level HTSC ( T = T _ c 2J, T _ c 1g, T _ c ) is determined. The feasibility of the topological phase transition, i.e., the Berezinsky–Kosterlitz–Thouless transition, in the Josephson medium at T _ c 2J < T _BKT < T _ c 1g “in transport current” is established, and its feasibility conditions are studied.