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The study of phase diagrams of specific superconductors helps us to understand their fundamental superconducting state properties. In presented work, the influence of granularity on superconducting state of polycrystalline copper-based CuBa₂Ca₃Cu₄O_10+δ material is studied with SQUID dc magnetometry technique. Although high quality of target phase is confirmed by high values of upper critical field H_c2 (91 T at 77 K) and irreversibility field H_irr (21 T at 77 K), there is a strong limitation of intergrain critical current density with regard to intragrain one. Simultaneously, iron-based polycrystalline Li_x(C₂H₈N₂)(Fe_ySe_zS_1−z) intercalated systems reveal big amount of magnetic inhomogeneities, which are supposed to co-exist with superconducting phases well below T_c. In order to investigate H_c2(T) phase diagram in this case, ac susceptibility measurements in external dc bias field were applied.

The seminar will be given in English on-site in room 203, though the ZOOM transmission will be available.

Zoom information.