Substrate surface engineering for functional ceramic thin film growth

A concept is introduced, using oxide substrates for functional ceramic thin film deposition beyond their usual application as chemical inert, lattice-matched support for the films. The substrates are applied as a functional element in order to controllably modify the atom arrangement and the growth mode of cuprate superconductors and colossal magnetoresistance materials. These materials have been chosen as prototypes of the general class of perovskite functional ceramics. One example studied is the use of epitaxial strain to adjust the relative positions of cations and anions in the film and thus modify their physical properties. The other makes use of vicinal cut SrTiO3 which enables the fabrication of regular nanoscale step and terrace structures. In YBa2Cu3O7-x thin films grown on vicinal cut SrTiO3 single crystals a regular array of antiphase boundaries is generated causing an anisotropic enhancement of flux-line pinning. In the case of La-Ca-Mn-O thin films grown on vicinal cut substrates it could be demonstrated that magnetic in-plane anisotropy is achieved.