Correlation of large dielectric response with the ordering transitions inPr0.67Ca0.33MnO3

Abstract

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, \ensuremath{\sim}220 K (charge ordering), \ensuremath{\sim}130 K (antiferromagnetic ordering), and \ensuremath{\sim}117 K (spin canting). An equally strong feature is also seen at \ensuremath{\sim}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.