2000/08/02 by Guo-meng Zhao, D. J. Kang, Zhao, Guo-meng +11
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.cond-mat/0008029
4 pages, 4 figures
arxiv created 2000/08/02 · arxiv updated 2009/11/30
Oxygen-isotope effects on the intrinsic resistivity have been studied in high-quality epitaxial thin films of La0.75Ca0.25MnO3 and Nd0.7Sr0.3MnO3. We found that the residual resistivity ρo increases by about 15(3)% upon replacing 16O by 18O. This provides strong evidence for the presence of small or intermediate-size polarons in the metallic ferromagnetic state. Furthermore, the temperature dependent part of the resistivity at low temperatures consists of an AT4.5 term contributed from 2-magnon scattering, and a Bωs/\sinh2(ℏωs/2kBT) term which arises from scattering by a soft optical phonon mode. The absolute magnitudes of the coefficient A and the phonon frequency ℏωs for both isotope samples are in quantitative agreement with theoretical predictions.