Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films

Abstract

We report a study on the superconducting properties of e-doped Sr0.88La0.12CuO2 (SLCO) thin films. SLCO has an infinite layer structure consisting of CuO2 planes, 3.40 angstrom apart, separated by Sr, La planes. Highly c-axis oriented thin films, with a critical temperature of 22-23 K, were epitaxially grown by sputtering. Their resistive transition hardly broadens under a perpendicular magnetic field, giving a narrow vortex liquid region. The critical current densities J(c) measured magnetically and by transport are in the 10(5)-10(6) A cm(-2) range at 4.2 K. The dependence of Jc on the orientation theta of the magnetic field, given by transport measurements, shows that, in contrast to highly anisotropic Bi2Sr2CaCu2Oy, there is no two-dimensional (2D) angular scaling: J(c)(theta, H) not equal J(c)(H-perpendicular to = H sin theta) and in parallel magnetic field Jc decreases with increasing fields. We also found an indication of a quasi-oscillatory behaviour of Jc(H-parallel to) possibly due to the successive entry of rows of vortices. In addition, the temperature dependence of the critical current is rather close to the behaviour derived from the Ginzburg-Landau theory. So, compared to BiSrCaCuO, this model cuprate appears to be much less anisotropic due to well coupled CuO2 planes and presents a more conventional behaviour.