Strong oxygen-isotope effect on the intrinsic resistivity in the ferromagnetic state of manganites - art. no. 060402

Oxygen-isotope effects on the intrinsic resistivity have been studied in hi gh-quality epitaxial thin films of La0.75Ca0.25MnO3 and Nd0.7Sr0.3MnO3. We found that the residual resistivity rho (o) increases by about 15(3)% upon replacing O-16 by O-18. Furthermore, the temperature dependent part of the resistivity at low temperatures consists of an A T-4.5 term contributed fro m two-magnon scattering, and a B omega (s)/sinh(2)((h) over bar omega (s)/2 k(B)T) term which arises from scattering by a soft optical phonon mode. The absolute magnitudes of the coefficient A and the phonon energy (h) over ba r omega (s) for both isotope samples are in quantitative agreement with the oretical predictions.