THIN-FILM DEPOSITION OF A NEW CUBIC PEROVSKITE, LA4+XBA1-XCU5O12+DELTA USED FOR THE REALIZATION OF MULTILAYERS WITH YBCO

A new oxygen-deficient cubic perovskite La4BaCu5O12+delta (LBCO) with a=3.877 angstrom has been stabilized in the form of a thin film by laser ablation, using (001) MgO and (001) LaAlO3 single crystals as substrates. The electron microscopy study of the c-axis films gave evidence for one-oriented growth on LaAlO3 ([100]LBCO parallel-to [100]LaAlO3) and two orientations on MgO ([100]LBCO parallel-to [100]MgO and [110]]LBCO parallel-to [100]MgO. A metallic behavior of the LBCO film is observed with a conductivity of 10(4) (OMEGA cm)-1 at 77 K. The thin-film deposition method has then been applied to the fabrication of ''YBCO/LBCO/YBCO', trilayer heterostructures. The multilayers deposited either on (001) MgO or (001) LaAlO3 substrates exhibit a c-axis orientation, with T(c)(R=0) of 87 K and 90 K, respectively. The superconducting properties of both YBCO layers of the structure, (YBCO)1 and (YBCO)2, have been found evidence for by SQUID measurements.