SUPERCONDUCTING AND STRUCTURAL-PROPERTIES OF ND2-XCEXCUO4-Y THIN-FILMS ON PEROVSKITE AND FLUORITE SUBSTRATES

High quality epitaxial Nd2-xCeCuO4-y (NCCO) thin films were fabricated on various substrates by pulsed-laser deposition using N2O reactive g as. The similarities and dissimilarities of the superconducting and st ructural properties of NCCO films, on perovskite-type substrates such as LaAlO3, NdGaO3, and SrTiO3 and on a fluorite-type substrate of yttr ia-stabilized zirconia (YSZ), were investigated systematically as a fu nction of film thickness by transport measurements and structural anal ysis. A remarkable reduction of T(c) was observed when the film was th inner than a critical thickness, which strongly depends on the substra te. The critical thicknesses for which T(c) is 80% of T(c max) are 120 0, 1000, 600, and 450 angstrom for LaAlO3, NdGaO3, SrTiO3, and YSZ, re spectively. YSZ turns out to be the best candidate for the growth of v ery thin NCCO films among the substrates studied. These results show a strong correlation between the strain and T(c) in NCCO thin films and point the way to the fabrication of n-type superconducting electric f ield devices using ultrathin NCCO films.