Continuous and topological phase transitions in the Josephson medium of granular high-temperature superconductor DyBa2Cu3O7–δ

In this work, fundamental studies of the influence of magnetoactive rare–earth atoms contained in the 1:2:3 high-temperature superconductors (HTSC) structure on the course of continuous and topological phase transitions in the Josephson medium of two-level high-temperature superconductors were carried out for the first time using the example of granular HTSC DyBa2Cu3O7-δ. It is shown that the presence of magnetoactive atoms and a non-zero internal magnetic field Hint enhances dissipation processes and leads to a significant decrease in the critical temperatures of continuous phase transitions occurring in the region of existence of the resistivity of the Josephson medium; but it does not affect the nature of topological phase transitions, which is consistent with the previously established independence of topological phases arising as a result of the Berezinskii–Kosterlitz–Thouless (BKT) phase transition from the type of external influence.