Ordering of polarons in Pr0.5Ca0.5MnO3

We report detailed dielectric investigations of Pr1−xCaxMnO3 (PCMO, x=0.5) ceramics, a member of the perovskite manganite family that exhibits a colossal magnetoresistance. Analysis of the electrical conductivity and dielectric constant data revealed that in the low temperature phase, below 42 K, small polarons are responsible for the charge transport in the system. This provides a new understanding of the phase diagrams in PCMO systems