Strain engineering magnetic frustration in perovskite oxide thin films

Our first-principles results show that geometric frustration can be induced in thin films of multiferroic BiFeO3. We find that competing magnetic interactions occur in the so-called super-tetragonal phase of this material, which can be grown on strongly-compressive substrates. We show that the frustration level can be tuned by appropriately choosing the substrate; in fact, the three-dimensional spin order gets totally annihilated in a narrow range of epitaxial strains. We argue that the effects revealed here are not exclusive to BiFeO3, and predict that they also occur in multiferroic BiCoO3.