Epitaxial growth of metastable La0.67Sr0.33MnO3−δ films by using Sr3Al2O6 as multifunctional buffer layers

In doped manganites, a substantial tuning of the magnetic and electrical transport properties can be realized by engineering the concentration of oxygen vacancies. To date, most oxygen-deficient La1−xSrxMnO3−δ (0 ≤ x ≤ 1) films are synthesized by after-growth treatments. However, the direct growth of La1−xSrxMnO3−δ films remains challenging due to the metastability of this material. Here, we report the epitaxial growth of high quality single crystalline La0.67Sr0.33MnO3−δ films with an extremely large out-of-plane lattice parameter of 4.26 Å by reactive oxide molecular beam epitaxy. To stabilize this metastable phase, Sr3Al2O6 buffer layers are used to block the oxygen diffusion from the SrTiO3 substrate to the film during the growth process. This work provides an efficient way to obtain metastable La0.67Sr0.33MnO3−δ films.