Epitaxial stabilization and crystal symmetry of ultra-thin heterostructures of (La,Nd)NiO3/LaAlO3

Recently, interface-controlled heterostructures containing ultra-thin layers of correlated oxides have attracted considerable attention. At the same time, novel synthesis methods based on epitaxial stabilization have enabled a route to stabilization of unusual phases of rare-earth nickelates far away from the bulk equilibrium. Specific features of atomic structure at the interface between rare-earth nickelates and LaAlO3 and SrTiO3, the role of strain and crystal geometry resulting in the formation of unusual phases of ultra-thin layers of nickelates will be discussed in detail. The experimental results have been deduced from a combination of synchrotron based XRD, RHEED, high-resolution electron diffraction and soft x-ray spectroscopy.