  We report the detailed study of dielectric response of Pr(0.6)Ca(0.4)MnO(3)
(PCMO), member of manganite family showing colossal magnetoresistance.
Measurements have been performed on four polycrystalline samples and four
single crystals, allowing us to compare and extract the essence of dielectric
response in the material. High frequency dielectric function is found to be 30,
as expected for the perovskite material. Dielectric relaxation is found in
frequency window of 20Hz-1MHz at temperatures of 50-200K that yields to
colossal low-frequency dielectric function, i.e. static dielectric constant.
Static dielectric constant is always colossal, but varies considerably in
different samples from 1000 until 100000. The measured data can be simulated
very well by blocking (surface barrier) capacitance in series with sample
resistance. This indicates that the large dielectric constant in PCMO arises
from the Schottky barriers at electrical contacts. Measurements in magnetic
field and with d.c. bias support this interpretation. Weak anomaly at the
charge ordering temperature can also be attributed to interplay of sample and
contact resistance. We comment our results in the framework of related studies
by other groups.
