Reversible magnetization and superconducting properties of the four-layered superconductor with

Reversible magnetization of grain-aligned Ba 2 Ca 3 Cu 4 O 8 + y ( F , O ) 2 (F-0234) with T c ≃ 90.6 K , which is a member with n=4 in the new homologous series Ba 2 Ca n − 1 Cu n O 2 n ( F , O ) 2 was investigated using the Hao–Clem model and fluctuation theories. The almost temperature independence of the Ginzburg–Landau parameter ( κ ) up to 0.9 T / T c and the crossover point in M(T) indicated less 2D character, suggesting no drastic decrease in interlayer coupling compared to other high-Tc cuprate superconductors. The relatively strong interlayer coupling results from the smallest thickness of the charge reservoir block among other multilayered systems. On the other hand, the λ ab ( 0 ) and H c ( 0 ) values derived from the Hao–Clem analysis strongly suggest that the decrease in Tc is due to both the decrease in the carrier density and weakened pairing strength.