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| Format: | Artículo científico |
| Sprache: | en |
| Veröffentlicht: |
Sociedade Brasileira de Física
2014
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| Online-Zugang: | https://www.redalyc.org/articulo.oa?id=46431147002 |
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Inhaltsangabe:
- The Non-Adiabatic Polaron Model Revisited Fabian E. N. Ramirez José Antonio Souza Física, Astronomía y Matemáticas Manganites Small polaron Transport mechanism Electrical resistivity Abstract We revisit Holstein’s polaron model to derive an extension of the expression for the thermal dependence of the electrical resistivity in the non-adiabatic small-polaron regime. Our analysis relaxes Holstein’s assumption that the vibrational-mode energies ωk are much smaller than the thermal energy kB T and substitutes a fifth-order expansion in powers of ωk /kB T for the linear approximation in the expression for the quasiparticle hopping probability in the original treatment. The resulting expression for the electri- cal resistivity has the form ρ(T ) = ρ0 T 3/2 exp(Ea /kB T − C/T 3 + D/T 5 ), where C and D are constants related to the molecule–electron interaction energy, or alternatively to the polaron binding energy, and the dispersion relation of the vibrational normal modes. We show that experimen- tal data for the La1−x Cax MnO3 (x = 0.30, 0.34, 0.40, and 0.45) manganite system, which are poorly fitted by the conventional non-adiabatic model, are remarkably well described by the more accurate expression. Our results sug- gest that, under conditions favoring high resistivity, the higher-order terms associated with the constants C and D in the above expression should taken into account in compar- isons between theoretical and experimental results for the temperature-dependent transport properties of transition- metal oxides. 2014 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46431147002 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.4 Vol.44