CHARACTERIZATION OF CRITICAL CURRENT FOR HIGH JC SINGLE-CRYSTAL YBA2CU3OY THIN-FILM ON LAAIO3 DEPOSITED BY DC MAGNETRON SPUTTERING

A single crystal YBa2Cu3Oy thin film is deposited on a (100)LaAlO3 substrate by the DC magnetron sputtering technique. Its T(c)(R=O) was measured to be 90.0 K. The critical current density, J(c)(H,T), has been investigated under applied magnetic field up to 7 T and in the temperature range from 64 to 79 K. A value of 4.9 x 10(6) A/cm2 for the critical current density J(c) has been measured for our thin film at 77 K and under zero field. The magnetic field dependence of J(c)(H,T) can be expressed with a function: J(c)(H,T) = CJ(c)(O,T)/(H+H(o)). The temperature dependence of J(c) (free of external magnetic field) is proportional to (T(c)-T). But under applied magnetic fields, the temperature dependence of J(c)(H,T) can be fitted with a function of J(c)(H,T) = J(c)(H,O)(1-alpha-t-beta-t2), this means that the critical current densities are limited by the flux creep when subjected to an applied magnetic field.