Competing Dielectric Phases and Detailed Balance in Thin Film Manganites

Mixed-valence manganites exhibit a rich variety of crystallographic, electronic, and magnetic phases that compete in phase-separated ground states. We present frequency-dependent measurements of the complex capacitance of thin La$_{1-y}$Pr$_{y}$Ca$_{0.33}$MnO$_{3}$ films together with an analysis that enables the simultaneous characterization of the competing paramagnetic insulating and the charge-ordered insulating phases. Resistance measurements in thin films are incapable of distinguishing these phases. Our analysis provides the individual time-scales and relative amplitudes of each phase at fixed temperatures in the range 100K-300K, allowing the determination of the activation energies and transition temperatures of each phase. Analysis of the time-scales and the relative proportions of each phase uncover a detailed balance equation describing the dynamic conversion between the phases during the polarization process. The competition of these dielectric phases is also studied as a function of external strain and magnetic field, demonstrating tunable dielectric constants and magnetic anisotropy in their transition temperatures.