Deterioration of functional properties at the interfaces of perovskite-based doped
manganites, like La0.67Sr0.33MnO3 (LSMO), is a common problem that restricts spintronic
applications of the manganite thin films [1]. Various mechanisms have been suggested to
explain the formation of clamped to the substrate or to the film surface layer with drastically
degraded ferromagnetic and metallic properties that are the so-called „dead layer“. The
substrate-induced epitaxial strain, which results in the distortion and corresponded spin,
orbital, and charge reconstructions at the interface, has been proposed to play a critical role in
the dead layer behavior. [2]. Coupling of MnO6 octahedra with respective substrate octahedra,
which is TiO6 in the case of SrTiO3(100) (STO) substrates, via corner shared oxygen ion and
the presence at the same time of lattice constant mismatch is the main reason for the distortions. The mechanism of octahedra distortion at the surface is similar, but the coupling
is formed with uncompleted octahedra of the uppermost MnO2 monolayer since this
termination is more stable for the (100)-oriented film growth. It is clear that disruption of the
coupling octahedra in the direction normal to film surface can provide decreasing of the
distortions reducing thus the dead layer thickness. Here we report on the dead layer reducing
due to artificial MnO6 octahedra decoupling at the interface and surface of LSMO ultrathin
films grown on STO(100) substrate. The decoupling was performed by an insertion of
additional SrO monolayers, which form the so-called Ruddlesden-Popper (RP) layered
manganite. It is well-known that the RP structure has n perovskite blocks (LSMO)
sandwiched between double sheets of rock salt (SrO) monolayers. The insertion of two SrO
monolayers can completely disrupt all corner shared MnO6 octahedra along the c-axis. For
this study 5 nm thick LSMO films with the additional SrO monolayers on surface and
interface were grown on STO(100) substrates by metalorganic aerosol deposition technique
controlling the epitaxial process by ellipsometry [3]. X-ray diffraction and AFM indicate
maintaining of a high structural perfection as well as the surface morphology quality in spite
of additional SrO monolayers. Transport property measurements display 10÷15 degrees
higher temperature of metal-insulator transition for artificially interfaced LSMO. Magnetic
measurements performed with SQUID and MOKE techniques demonstrate both enhanced
magnetization and Curie temperature for the interfaced films. Therefore, our study confirms
the dead layer reducing due to the decoupling of MnO6 octahedra by interfacing LSMO films
via RP-like insertion.