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La0.5Ca0.5MnO3 films; SrTiO3 substrates; epitaxy of films; structural distortion; electrical and magnetic measurements
Abstract:
La0.5Ca0.5MnO3 (LCMO) films of various thicknesses were epitaxially grown on (10 0) and (111) oriented SrTiO3 (STO) substrates by pulsed laser deposition (PLID) technique. It was observed that LCMO films on (10 0) STO behave as an insulator. However, the films on (111) STO show a metal to insulator transition, when their thicknesses exceed 145 nm. Jahn-Teller strain (epsilon(J-T)) was seen to decrease with increasing film thickness for the films on (111) STO while the films on (100) STO have large compressive epsilon(J-T) values for all thicknesses. Moreover, rocking curves and asymmetries of the diffraction peaks for the films on (111) STO substrates may indicate the formation of a mosaic structure, which can act as a relaxation mechanism, with the increasing film thickness. These observations suggest that the electronic properties of the LCMO thin films can be modified by structural changes imposed by the substrate. (c) 2007 Elsevier B.V. All rights reserved.
