The role of a superconducting seed layer in the structural and transport properties of EuBa2Cu3O7-x films

We report on the structural and transport properties of EuBa2Cu3O7-x (Eu123) films on SrTiO3 substrates. A substrate temperature 100degreesC higher than that used to deposit YBa2Cu3O7-x (Y123) is needed to grow high-performance Eu123 films directly on SrTiO3 substrates. However, this high-temperature restriction can be circumvented by inserting a seed layer (similar to12 nm) of Y123, Gd123, or Dy123 between the substrate and the Eu123. A structural analysis reveals that a transition region that promotes the growth of the a-axis is first formed on the surface of the substrate if the Eu123 is deposited directly on SrTiO3 at a temperature of less than <LF>800degreesC. On the other hand, the use of a seed layer of another superconducting material restructures the Eu123 to the right phase without forming this transition region. Eu123 films with critical temperatures of 94 K and critical current densities of 5.8x10(6) A/cm(2) at 75.5 K have been deposited under standard deposition conditions using such an approach. (C) 2003 American Institute of Physics.