SUPERCONDUCTING PROPERTIES OF EPITAXIAL LASER-ABLATED THIN-FILMS

We present experimental results obtained for high quality epitaxial th in films (film thicknesses around 5000 Angstrom rocking curve FWHM dow n to 0.1 degrees). These films are obtained by laser ablation of REBa( 2)Cu(3)O(7-delta) (RE = Y, Er) deposited on SrTio(3) and YSZ substrate s. The superconducting properties have been studied by complex suscept ibility in an extended AC field range (h(ac) less than or equal to 300 Oe) and show sharp magnetic transition width and high critical curren ts (10(7) A cm(-2) < j(c)(77 K) < 10(8) A cm(-2)). The loss peak is on ly weakly depressed by an increasing AC held and the observed shifts a re up to an order of magnitude lower than those observed for intragran ular contributions in bulk samples. The agreement with the behaviour e xpected from a critical state model is also discussed.