GROWTH, STRUCTURAL AND ELECTRICAL CHARACTERIZATION OF [(CA,SR)CUO2](M) [BACUO2](N) SUPERLATTICES/

In this paper we show that (CaCuO2)(m)/(BaCuO2)(n) and (SrCuO2)(m)/(Ba CuO2)(n) superlattices with good crystallographic quality can be engin eered by Pulsed Laser Deposition (PLD) in a wide range of composition, namely for n = 2 and m = 1-6. However, Sr- and Ca-based superlattices result to have qualitatively different electrical transport propertie s. Superconductivity is observed in Ca-containing superlattices only. This effect is explained by the large Ba double left right arrow Sr in terdiffusion. The resistivity behaviour of the Ca-containing superlatt ices grown at high oxygen pressure (greater than or equal to 0.2 mbar) is metallic with a full transition to a superconductive state at temp eratures as high as 70 K (zero resistance temperature). Such value of T-c, the highest till now reported for an artificial structure, is sti ll lower than those of the related CuBa2Can-1CunOx compounds (T-c = 11 6 K) obtained by high pressure synthesis. Such difference can be due e ither to a still unoptimized growth procedure or to the intrinsically higher disorder typical of these artificial structures. (C) 1998 Elsev ier Science B.V. All rights reserved.