Growth of [YBa2Cu3O7-δ]M/[PrBa2Cu3-xGaxO7-δ]N Superlattices by Pulsed Laser Deposition

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Abstract
PrBa2Cu3-x Ga x O7-δ thin films up to x=0.2 and YBa2Cu3O7-δ/PrBa2Cu2.8Ga0.2O7-δ superlattices have been grown by pulsed laser deposition (PLD) on {100} SrTiO3 substrate. The resitance of PrBa2Cu2.8Ga0.2O7-δ is 500 times higher at 77 K than the one of unsubstituted PrBa2Cu3O7-δ. At a growth temperature of 785°C, the multilayers have c-axis normal to the substrate surface and satellite peaks have been observed up to i=±3 on X-ray diffraction spectra. At a lower growth temperature the structure becomes oriented with a-axis normal to the growth interface. Secondary-ion mass spectrometry reveals no interdiffusion between Y and Pr and no diffusion of Ga into the YBa2Cu3O7-δ layer. The 15% RBS minimum yield reoorded for the superlattice indicates highly oriented growth. T c is around 10 K lower than the one of the equivalent decoupled multilayers grown from unsubstituted PrBa2Cu3O7-δ.