High-pressure growth of Ca2− x Na x CuO2Cl2 single crystals and pressure effect on superconductivity

Abstract: Single crystals of cuprate oxychloride superconductor Ca2− x Na x CuO2Cl2 (Na-CCOC) with a systematic variant T c as a function of Na content are synthesized under high pressure and high temperature. The pressure effect on the superconducting transition temperature in Na-CCOC single crystal is investigated by electrical resistance measurements up to 6.5GPa. It is found that the T c decreases almost linearly with increasing pressure, exhibiting a negative pressure shift, which is totally different pressure behavior from that of isostructural (La,Sr)2CuO4 and other cuprate superconductors. [Copyright &y& Elsevier]