Phase-selective growth of water-soluble strontium aluminate via sputtering deposition for freestanding oxide membranes

We report the epitaxial growth of high-quality water-soluble strontium aluminate films via sputtering deposition. We systematically investigate the dependence of the films structural quality on the growth conditions and we show that we can selectively grow, using the same target, both the cubic Sr3Al2O6 and the tetragonal Sr4Al2O7 phases by varying the atmosphere during growth. Using these water-soluble sacrificial layers we then synthesize ferromagnetic freestanding Sm2NiMnO6 membranes. By means of X-ray diffraction, synchrotron spectroscopic techniques and SQUID magnetometry, we demonstrate that our freestanding films exhibit properties comparable to epitaxial films.