Characterization of YBa₂Cu₃O_7-delta single crystals grown from charges containing silver nitrate

Abstract

Single-crystal growth of YBa₂Cu₃O_{7- delta} has been studied using starting charges containing known amounts of Ag in the form of AgNO₃. The as-grown crystals are found to undergo a sharp transition to the superconducting state at 90 K, showing that the addition of AgNO₃ facilitates their oxygenation. The measured room-temperature resistivities, both in plane ( rho _ab) and out of plane (rho_c), for the grown crystals are found to be the lowest among the values reported so far. The anisotropy in resistivity ( rho _c/ rho _ab) at 300 K is found to be roughly one-half of the value measured for the crystals grown from charges free from AgNO₃. The angular dependence of transport critical current for the doped crystals has been measured at 82 K and for an applied magnetic field of 0.9 T. The results have been analysed using the existing theoretical models.