Ambient-pressure synthesis of single-crystal (formula presented) and their superconducting anisotropy

Abstract

We synthesized single crystalline (formula presented) under ambient pressure by using conventional materials and equipment. The single crystals of (formula presented) were of good quality, where the crystal structure refinements were successfully converged with (formula presented) The measurements of the magnetic properties yielded a sharp superconducting transition at 38 K with transition width (formula presented) The upper critical field for applied field parallel to the ab plane (formula presented) reveals a positive curvature, while (formula presented) parallel to the c axis (formula presented) increases linearly in temperature dependence, which yields a temperature dependence of the superconducting anisotropy ratio of (formula presented) with (formula presented) near (formula presented) and 4.0 at 25 K. © 2003 The American Physical Society.