Polaron relaxation related to localized charge carriers in Pr 1-xCaxMnO3

Abstract

Low-temperature (23 ≤ T ≤ 150 K) dielectric properties of Pr 1-xCaxMnO3 (PCMO) (0.1 ≤ x ≤ 0.9) were investigated systematically. A thermally activated relaxation was found in both charge-ordered and no-charge-ordered samples with localized charge carriers, but it was not detected in samples with free carriers. The dielectric behaviour can be well described based on the Jonscher's power law or 'universal dielectric response'. Our results strongly support the point that the dielectric properties of PCMO are associated with the hopping motions of polaronic carriers among the localized centres. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.