Critical Current Properties of Hg(Re)1223 Single Crystals with Various Oxygen Content

Abstract

ABSTRACTHigh quality single crystals of Hg(Re)1223 were grown by the flux method using BaZrO3 crucible, which is stable against molten Ba-Cu-O. The maximum size of the obtained crystal was 1 × 1.1 × 0.1mm3 in dimension. X-ray diffraction analysis revealed that grown crystals are of Hg(Re)1223 single phase with c0 = 15.7 å. 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 postannealing under various conditions did not affect largely for critical current properties. Irreversibility lines of the Hg(Re)1223 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.