Strain-Induced Ferromagnetism and Magnetoresistance in Epitaxial Thin Films of LaCoO3 Prepared by Polymer-Assisted Deposition

High quality epitaxial thin films of LaCoO3 on SrTiO3 have been prepared by spin-coating of a metal/polymeric aqueous solution. The films (approximate to 17 nm) are homogeneous and smooth over large areas. The characteristic low-spin (LS) state is replaced by a higher spin configuration of Co(III), due to strain-induced distortions of the CoO6 octahedra, introducing a ferromagnetic interaction and negative magnetoresistance below T-C = 85 K. This simple chemical method produces the high-quality films required for either fundamental studies or applications, similar to physical deposition techniques.