A-AXIS ORIENTED EPITAXIAL YBA2CU3O7-Y/PRBA2CU3-XNBXO7-Z MULTISTRUCTURES

Using the pulsed laser deposition technique, we have successfully prepared a-axis oriented PrBa2Cu3-xNbxO7-z (PBCNO)(x=0-1.5) films and YBa2Cu3O7-x, (YBCO)/PBCNO heterorepitaxial multilayer structures. For the PBCNO films, the resistivity showed semiconducting behavior at all Nb substitution levels investigated. The resistivity increased with increasing Nb content, reaching a value of 10(4) OMEGA cm at 100 K for a 300-angstrom-thick film with x=1.0. Using (100)SrTiO3 (STO) as a substrate, the following multilayer structures were successfully formed: (100)PBCNO(x=1.0)/(100)YBCO/(100)PBCO//STO, (001) YBCO/(100)PBCNO(x=1.0)/(100)PBCO//STO, and (100)YBCO/(100)PBCO/(100)PBCNO(x=1.0)/(100)PBCO//STO. The bottom and top YBCO layers in the (100)YBCO/(100)PBCO/(100)PBCNO/(100)PBCO/(100)YBCO//STO structure showed superconducting transition temperatures (zero resistance) of 82 and 83 K, respectively. The interlayer resistivity of the 200-angstrom-thick PBCNO(x=1) interlayer was as high as 10(5) OMEGA cm at 30 K.