Optical soft mode driven ferroelectric phase transition was discovered in IR spectra of tensile strained ferromagnetic EuO thin films. The phase transition was predicted already ten years ago in films with 4% strain, but we have observed it only now in films with 6.4% strain. As such strain tends to relax after the epitaxial growth of only a few monolayers, we have achieved it in (EuO)2/(BaO)2 superlattices grown epitaxially on LSAT substrates. The observation is supported by a new DFT calculation.
Contact person: Stanislav Kamba