Electrical transport in the ferromagnetic state of manganites: Small-polaron metallic conduction at low temperatures

Abstract

We report measurements of the resistivity in the ferromagnetic state of epitaxial thin films of La_{1-x}Ca_{x}MnO_{3} and the low temperature specific heat of a polycrystalline La_{0.8}Ca_{0.2}MnO_{3}. The resistivity below 100 K can be well fitted by ρ- ρ_{o} = E ω_{s}/sinh^{2}(\hbar ω_{s}/2k_{B}T) with \hbar ω_{s}/k_{B} \simeq 100 K and E being a constant. Such behavior is consistent with small-polaron coherent motion which involves a relaxation due to a soft optical phonon mode. The specific heat data also suggest the existence of such a phonon mode. The present results thus provide evidence for small-polaron metallic conduction in the ferromagnetic state of manganites.

4 pages, 4 figures, submitted to PRL

References in corpus (5)

• Carrier Density Collapse and Colossal Magnetoresistance in Doped Manganites
• Mobile small polaron
• Polaron Absorption in a Perovskite Manganite La0.7Ca0.3MnO3
• The Essential Interactions in Oxides and Spectral Weight Transfer in Doped Manganites
• Temperature dependent scattering rate and optical mass of ferromagnetic metallic manganites

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