Structural, magnetic, and transport properties of pulsed-laser deposition La 0.65 Ca 0.35 MnO 3 films grown under differ
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D.G. Naugleb) and K.D.D. Rathnayaka Department of Physics, Texas A&M University, College Station, Texas 77843
I.N. Chukanova Institute for Single Crystals, National Academy of Sciences, Kharkov 61001, Ukraine
J.H. Ross Department of Physics, Texas A&M University, College Station, Texas 77843
V.M. Ishchuk Institute for Single Crystals, National Academy of Sciences, Kharkov 61001, Ukraine (Received 26 February 2003; accepted 10 July 2003)
The structural, transport, and magnetic properties of La0.65Ca0.35MnO3 films grown on MgO substrates by pulsed-laser deposition under different substrate arrangements in the laser plume were studied. In addition to the standard substrate arrangement in the main stream of particles, substrate arrangements in the periphery area of the laser plume and in an area shielded from the plume were used. In the latter case, the deposition occurs from the flux that is reflected from a side screen. It was found that the substrate arrangement influences considerably the surface topography, structure, chemical composition, magnetic, transport, and magnetoresistance properties of the films. It was found that the substrate arrangements in the periphery area of the laser plume and in the shielded area of the plume eliminate deposition of large particulates. The latter arrangement is the most effective in elimination of particulate deposition. In this case, the film has the smoothest surface with root mean square roughness of about 2 nm. The data obtained revealed interesting correlations between the structural and transport properties as well. In particular, films deposited in the periphery and shielded areas of the laser plume have increased nonstoichiometry (La deficiency), higher resistivity, and broader magnetic transitions. The polycrystalline nature of the films studied is taken into account in the discussion of their transport properties. I. INTRODUCTION
The pulsed-laser deposition (PLD) technique is a powerful and universal tool for preparing films of multicomponent compounds. The main physical phenomena in laser ablation can be considered as established,1–4 although some processes are still being studied and debated. At optimal deposition conditions, a rapid localized heating by the laser pulse causes intense evaporation of target material. This results in the formation of a hightemperature plasma of ions, atoms, molecules, electrons, and so forth. This so-called laser plume is directed normal to and away from the target surface. The ejected material is deposited onto a substrate placed in its path. a) b)
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J. Mater. Res., Vol. 18, No. 10, Oct 2003 Downloaded: 16 Mar 2015
PLD was found to be effective in preparation of highquality films of perovskite-related oxides, which, along with fundamental importance for solid-state physics, also offer different applications in advanced technology. Here, the high-Tc superconducting cuprates and colossalmagnetoresistance (CMR) doped manganites5,6
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