Fish-tail Effect and Irreversibility Field of (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{x}$-(LiF)$_{y}$ superconductor

P. Badica; V. Sandu; G. Aldica; A. Iyo; H. Kito; M. Hirai; Y. Tanaka

doi:10.1007/s10948-005-0023-0

paper

Fish-tail Effect and Irreversibility Field of (Cu,C)Ba $_{2}$ Ca $_{3}$ Cu $_{4}$ O $_{x}$ -(LiF) $_{y}$ superconductor

arXiv:cond-mat/0505494 · doi:10.1007/s10948-005-0023-0

Abstract

Addition of (LiF) $_{y < 0.15}$ , and of proper amount of (AgO) $_{z = 0.45 - 0.8}$ as oxidizing agent, to (Cu,C)Ba $_{2}$ Ca $_{3}$ Cu $_{4}$ O $_{10 + d}$ superconductor is useful to control and shift the doping characteristics (hole density and distribution, and level of disorder) into the region where the irreversible properties, i.e. fish-tail effect (FTE) and irreversibility field H $_{i r r}$ , are improved. Among notable effects are the development of the second magnetization peak with a higher amplitude J $_{c}$ , max and the enhancement of H $_{i r r}$ at high temperatures, above a certain value T* which depends on both y $_{L i F}$ and z $_{A g O}$ . The best results are obtained for the sample with y $_{L i F}$ =0.1 and z $_{A g O}$ =0.73. This sample preserves its single phase Cu,C-1234 composition. The influence on the FTE and H $_{i r r}$ of the interplay between doping characteristics, controlled by LiF and AgO content, is discussed.

28 pages, accepted to J. Supercond

Fish-tail Effect and Irreversibility Field of (Cu,C)Ba2​Ca3​Cu4​Ox​-(LiF)y​ superconductor

Abstract

Fish-tail Effect and Irreversibility Field of (Cu,C)Ba $_{2}$ Ca $_{3}$ Cu $_{4}$ O $_{x}$ -(LiF) $_{y}$ superconductor