Abstract
A chemical solution deposition (CSD) procedure was used to prepare epitaxial lanthanum calcium manganese oxide (LCMO) thin films on (100) SrTiO3 single-crystal substrates. The colossal magnetoresistance (CMR) properties of the films were found to be comparable to those processed with vacuum deposition techniques and to bulk samples. The (200) LCMO d-spacing and insulator-metal transition temperature (TIM) were measured for films heat-treated at different temperatures, partial pressures of O2, and different times. The variations observed suggest a direct link between lattice parameter and TIM, as can be understood through their mutual dependence on the Mn4+/Mn3+ ratio. The measurements also suggest that film and powder samples crystallize Mn41-rich with respect to the Ca-substitution level, consistent with the larger lattice parameter and higher TIM observed following short heat treatments at high temperatures or long treatments at lower temperatures. Films refired in reducing conditions had the largest (200) d-spacing and slightly lower TIM, as expected from the 30% Ca-substitution level and consistent with the LCMO electronic/magnetic phase diagram constructed for bulk samples.
Published Version
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