High pressure synthesis and properties of HgBa2Ca4Cu5Oy (Hg-1245) superconductor

We have synthesized an almost single phase sample of HgBa2Ca4Cu5Oy with Tc of 108K using a high pressure and high temperature technique. The carrier concentration, NH, was deduced from the Hall coefficient RH using a simple relation (NH=1/(eRH)) at 300 K and the Hall number per CuO2 plane was estimated to be 0.12 for this sample. We also observed a T2 dependence of the Hall angle (cot*cH). The critical current density (Jc) and irreversible field (Birr) have been estimated from measurements of magnetic hysteresis loops assuming Bean's critical state model. The Birr for this sample as a function of temperature was lower than HgBa2Ca4Cu5Oy (Hg-1223). This result suggests that the anisotropy in Hg-1245 is seem to be larger than that in Hg-1223 and inter-layer coupling among five CuO2 planes in Hg-1245 becomes weaker than that in Hg-1223 by adding two CuO2 planes.