Frequency-dependent capacitance measurements and transport measurements tuned to reveal system impedance have been performed on epitaxial thin films of ${\mathrm{Pr}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_3.$ These reflect strong dielectric response features correlated to the various ordering transition temperatures in the system, namely, ∼220 K (charge ordering), ∼130 K (antiferromagnetic ordering), and ∼117 K (spin canting). An equally strong feature is also seen at ∼125 K, which does not correspond to any reported transition. The enhanced dielectric response at the transitions is attributed to the nonequilibrium transport and slow carrier reorganization dynamics defined by polaronic hopping and magnetic frustration.

• Received 12 June 2000

DOI:https://doi.org/10.1103/PhysRevB.62.R11961