The present invention relates to a method for producing a defect-containing superconducting film, the method comprising (a) depositing a phase-separable layer epitaxially onto a biaxially-textured substrate, wherein the phase-separable layer includes at least two phase-separable components; (b) achieving nanoscale phase separation of the phase-separable layer such that a phase-separated layer including at least two phase-separated components is produced; and (c) depositing a superconducting film epitaxially onto said phase-separated components of the phase-separated layer such that nanoscale features of the phase-separated layer are propagated into the superconducting film.