Structural, magnetic, and transport properties of pulsed-laser deposition La0.65Ca0.35MnO3 films grown under different substrate arrangements in the laser plume

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.