Evidence for the immobile bipolaron formation in the paramagnetic state of the magnetoresistive manganites

Abstract

Recent research suggests that the charge carriers in the paramagnetic state of the magnetoresistive manganites are small polarons. Here we report studies of the oxygen-isotope effects on the intrinsic resistivity and thermoelectric power in several ferromagnetic manganites. The precise measurements of these isotope effects allow us to make a quantitative data analysis. Our results do not support a simple small-polaron model, but rather provide compelling evidence for the presence of small immobile bipolarons, i.e., pairs of small polarons. Since the bipolarons in the manganites are immobile, the present result alone appears not to give a positive support to the bipolaronic superconductivity theory for the copper-based perovskites.

arXiv comment6 pages, 5 figures, monor corrections

References in corpus (6)

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• Dynamic Jahn-Teller Effect and Colossal Magnetoresistance in $L{a}_{1-x}{A}_{x}Mn{O}_3$
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Cited by in corpus (5)

• Extrinsic Magnetotransport Phenomena in Ferromagnetic Oxides
• Phase coexistence and resistivity near the ferromagnetic transition of manganites
• Polaronic excitations in CMR manganite films
• Unusual temperature dependence of the oxygen-isotope effect on the exchange-energy of $L{a}_{1-x}C{a}_{x}Mn{O}_3$ at high temperatures
• Direct Correlation between 1/f-magneto-noise and magnetoresistance in La0.7Sr0.3MnO3 and (La0.5Pr0.2)Ba0.3MnO3 manganites