Enhanced pinning and peak effect in overdoped (Hg, Pb)(Sr, Ba)2Ca2Cu3O8+δ superconductors

Abstract

“Peak effect” was observed in the magnetization hysteresis loops of both (Hg, Pb)(Sr, Ba)2Ca2Cu3O8+δ polycrystalline bulks and single crystals, and the influence of postannealing on the peak position (Hs.p.) was studied, where “s.p.” means second peak. It was shown that the Hs.p.–T characteristic curves for a Sr-rich (Hg, Pb)-1223 were located in higher fields than those reported for conventional Hg-1223 and Tl-1223 single crystals, corresponding to reduced lattice parameters and electronic anisotropy of the studied compounds. The Jc (77 K) values of 3×105, 2.8×104, and 1.8×104 A/cm2 were estimated for the present single-crystal sample at H=0, 1, and 2 T, respectively. This confirms the excellent flux-pinning property of (Hg, Pb)(Sr, Ba)2Ca2Cu3O8+δ, making them potential candidates for high current applications.