Journal of alloys and compounds vol:195 issue:1-2 pages:191-194
We have studied magnetoresistance of the YBa2Cu3O7/PrBa2Cu3O7 (YBCO/PrBCO) superlattices with different thickness of the separator layer (YBCO/PrBCO = 1:1, 1:3 and 1:5) in fields up to 12T at T < T(c). An excellent fitting by the Larkin two-dimensional superconducting fluctuation theory with only two scaling parameters ( A(T) and H(PHI)(T)) for each R(T) curve shows that it is possible to apply this approach to interpret our magnetoresistance data. The resistive transition broadening in a magnetic field can be related to giant conductivity fluctuations in the quasi two- dimensional double CuO2 superconducting layers ir YBCO. The magnetoresistance increases with further separation of YBCO in the superlattices with a larger thickness of the PrBCO separator layers. For YBCO/PBCO=1:3 and 1:5 superlattices, the first scaling parameter A(T) determined by the fluctuation amplitude follows quite well the Larkin beta(T) function typical for 2D systems. For YBCO/PrBCO=1:1, the YBCO layers are not completely decoupled and A(T) deviates from beta(T). The temperature dependence of the second scaling parameter H(PHI) (T), the phase coherence breaking field, is consistent with the theoretical prediction by Reizer for the quasi-two-dimensional electron-electron interactions.