Sub-unit cell layer-by-layer growth of Fe3O4, MgO, and Sr2RuO4 thin films

The use of oxide materials in oxide electronics requires their controlled epitaxial growth. Recently, it was shown that Reflection High Energy Electron Diffraction (RHEED) allows the growth of oxide thin films to be monitored, even at high oxygen pressures. Here, we report the sub-unit cell molecular or block layer growth of the oxide materials Sr2RuO4, MgO, and magnetite using Pulsed Laser Deposition (PLD) from stoichiometric targets. Whereas a single RHEED intensity oscillation is found to correspond to the growth of a single unit cell for perovskites such as SrTiO3 or doped LaMnO3, in materials where the unit cell is composed of several molecular layers or blocks with identical stoichiometry, sub-unit cell molecular or block layer growth is established, resulting in several RHEED intensity oscillations during the growth of a single unit cell.