Critical current properties of Hg(Re)1223 single crystals with various oxygen content

摘要

High quality single crystals of Hg(Re) 1223 were grown by the flux method using BaZrO{sub}3 crucible, which is stable against molten Ba-Cu-O. The maximum size of the obtained crystal was 1 × 1.1 × 0.1 mm{sup}3 in dimension. X-ray diffraction analysis revealed that grown crystals are of Hg(Re) 1223 single phase with C{sub}O = 15.7 A. In the magnetic hysteresis curves for post-annealed Hg(Re) 1223 single crystals under H∥C, large second peak effect was found with steep increase of magnetization at approximately 2～3kOe independent of temperature. The peak field systematically increased with a decrease of temperature, suggesting generation of field-induced pinning. Critical current density and irreversibility field of single crystals were dependent on synthesis batch, possibly due to the difference in resulting concentration of Re, while post-annealing under various conditions did not affect largely for critical current properties. Irreversibility lines of the Hg(Re)1 223 single crystals locate at higher fields than that of Re-free Hg1223. This suggests that electromagnetic anisotropy is reduced by Re-doping, which is consistent with the recent results on the resistive anisotropy in the normal state.