Percolation transitions tuned by temperature, magnetic field, and time in a phase-separated manganite

Abstract

In some hole-doped manganites, the application of various external perturbations can destabilize ${\mathrm{Mn}}^{3+}/{\mathrm{Mn}}^{4+}$ ordering and favor ferromagnetic interactions, resulting in large resistivity decreases connected with significant magnetization increases. The present paper reports on studies of such phenomena, carried out in ${\mathrm{Pr}}_{0.63}{\mathrm{Ca}}_{0.37}{\mathrm{MnO}}_{3},$ as a function of temperature, magnetic field, or time. Combining in each case magnetization and resistivity measurements, it is shown that the insulator-metal transitions induced by these three parameters can be well described by the same percolation law $\ensuremath{\sigma}\ensuremath{\propto}(f\ensuremath{-}{f}_{c}{)}^{s},$ relating electric conductivity $(\ensuremath{\sigma})$ to the ferromagnetic fraction $(f).$