COMPARISON OF BA2YCU3O7-DELTA FILMS ON NDGAO3 AND LAALO3

We have studied the properties of 100 nm films of Ba2YCu3O7-delta (BYCO) grown on LaA1O3(100) and NdGaO3(100) by co-evaporation of Cu, Y, and BaF2 followed by a two-stage anneal ex situ. We find that the structural properties of the films on both substrates are optimized when the maximum temperature of the anneal is 900-degrees-C, while the superconducting properties are slightly better if the maximum temperature does not exceed 875-degrees-C. Films on LaAlO3 can tolerate a longer time at the maximum annealing temperature than can films on NdGaO3. We postulate that this is due to a reaction between Ga in the NdGaO3 and at least one of the constituents of the BYCO film (probably Y).