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

We report a study on the superconducting properties of e-doped Sr_0.88La_0.12CuO₂ (SLCO) thin films. SLCO has an infinite layer structure consisting of CuO₂ planes, 3.40 Å 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 10⁵–10⁶ A cm ^{− 2} range at 4.2 K. The dependence of J_c on the orientation θ of the magnetic field, given by transport measurements, shows that, in contrast to highly anisotropic Bi₂Sr₂CaCu₂O_y, there is no two-dimensional (2D) angular scaling: and in parallel magnetic field J_c decreases with increasing fields. We also found an indication of a quasi-oscillatory behaviour of 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.