Small polaronic transport in oxygen-deficient La0.7Ca0.3MnO3-δ thin films -: art. no. 214427

By adjusting the oxygen contents in high-quality epitaxial La0.7Ca0.3MnO3-delta (LCMO) thin films, samples with different ferromagnetic and insulator-metal (I-M) transitions have been used to perform a series of measurements. Resistivity data of epitaxial oxygen-deficient LCMO films above the Curie temperature show activated behavior given by the small polaron model. In the region of the I-M transition temperatures T-P > 240 K, the T-P demonstrates a roughly linear dependence with an effective activation energy of E-hop in the small polaron expression. The remarkable well-fitted data and the correlation of E-hop with the I-M transition indicate the importance of polaronic transport in magnanites. The observed relationship between E-hop and T-P should be more essential in physics.