Superconducting Properties of Epitaxial Laser Ablated Thin Films

We present experimental results obtained for high quality epitaxial thin films (film thicknesses around 5000 A; rocking curve FWHM down to 0.1°). These films are obtained by laser ablation of REBa 2 Cu 3 O 7−δ (RE = Y, Er) deposited on SrTio 3 and YSZ substrates. The superconducting properties have been studied by complex susceptibility in an extended AC field range ( h ac ≤ 300 Oe) and show sharp magnetic transition width and high critical currents (10 7 A cm −2 j c (77K) 8 A cm −2 ). The loss peak is only weakly depressed by an increasing AC field and the observed shifts are up to an order of magnitude lower than those observed for intragranular contributions in bulk samples. The agreement with the behaviour expected from a critical state model is also discussed.