Microstructure of Sr4Ru2O9 thin films and Bi3.25La0.75Ti3O12/Sr4Ru2O9 bilayers

It has been reported that using oxide bottom electrodes reduces the fatigue phenomenon in ferroelectric random access memories (FeRAM). For that aim, strontium ruthenate SrRuO3 was already used as bottom oxide electrode for ferroelectric thin films [1], but compounds with less ruthenium are more interesting from the economical and environmental point of view. We elaborate Sr4Ru2O9 thin films and bilayers Bi3.25La0.75Ti3O12/Sr4Ru2O9 by pulsed laser deposition. Sr4Ru2O9 compound differs from the other strontium ruthenates. It has a hexagonal perovskite structure, contains pentavalent ruthenium atoms, with octahedral sharing faces, thus building dimmers Ru2O9 [2]. All the other strontium ruthenates belong to the Ruddlesden Poppers homologous series, Srn+1RunO3n+1 (Sr2RuO4 corresponds to n=1 and SrRuO3 to n=∞). The common features of these compounds are an orthorhombic structure, tetravalent ruthenium atoms, and an octahedral surrounding by oxygen of ruthenium atoms.