The structure and interface characteristics of (LaVO3)6m(SrVO3)m superlattices deposited on (100)-SrTiO3 (STO) substrate were studied using Transmission Electron Microscopy (TEM). Cross-section TEM studies revealed that both LaVO3 (LVO) and SrVO3 (SV
O) layers are good single crystal quality and epitaxially grown with respect to the substrate. It is evidenced that LVO layers are made of two orientational variants of a distorted perovskite compatible with bulk LaVO3 while SVO layers suffers from a tetragonal distortion due to the substrate induced stain. Electron Energy Loss Spectroscopy (EELS) investigations indicate changes in the fine structure of the V L23 edge, related to a valence change between the LaVO3 and SrVO3 layers.
Epitaxial LaRh1/2Mn1/2O3 thin films have been grown on (001)-oriented LaAlO3 and SrTiO3 substrates using pulsed laser deposition. The optimized thin film samples are semiconducting and ferromagnetic with a Curie temperature close to 100 K, a coercive
field of 1200 Oe, and a saturation magnetization of 1.7muB per formula unit. The surface texture, structural, electrical, and magnetic properties of the LaRh1/2Mn1/2O3 films was examined as a function of the oxygen concentration during deposition. While an elevated oxygen concentration yields thin films with optimal magnetic properties, slightly lower oxygen concentrations result in films with improved texture and crystallinity.
The spectacular metal-to-insulator transition of V2O3 can be progressively suppressed in thin film samples. Evidence for phase separation was observed using microbridges as a mesoscopic probe of transport properties where the same film possesses doma
ins that exhibit a metal-to-insulator transition with clear first order features or remain metallic down to low temperatures. A simple model consisting of two parallel resistors can be used to quantify a phase coexistence scenario explaining the measured macroscopic transport properties. The interaction between film and substrate is the most plausible candidate to explain this extended phase coexistence as shown by a correlation between the transport properties and the structural data.
A series of epitaxial (LaVO3)6m(SrVO3)m superlattices having the same nominal composition as La6/7Sr1/7VO3, a Mott-Hubbard insulator, were grown with pulsed-laser deposition on [001]-oriented SrTiO3 substrates, and their superlattice period was varie
d. When m=1, the insulating resistivity of bulk-like La6/7Sr1/7VO3 is obtained; however, an increase in the periodicity (m>=2) results in metallic samples. Comparison of the superlattice periodicity with the coherence length of charge carriers in perovskite oxide heterostructures are used to understand these observations. A filling-controlled insulator-metal transition was induced by placing a single dopant layer of SrVO3 within LaVO3 layers of varying thickness.
Epitaxial La2NiMnO6 thin films have been grown on (001)-oriented SrTiO3 using the PLD technique. The thin films are semiconducting and FM with a TC close to 270K, a coercive field of 920Oe, and a saturation magnetization of 5muB per f.u. TEM, conduct
ed at RT, reveals a majority phase having I-centered structure with a=c=1.4asub and b=2asub along with a minority phase-domains having P-type structure (asub being the lattice parameter of the perovskite structure). A discusion on the presence of Ni/Mn long-range ordering, in light of recent literature on double perovskites La2NiMnO6 is presented.
