Percolation transitions tuned by temperature, magnetic field, and time in a phase-separated manganite - art. no. 064402

In some hole-doped manganites, the application of various external perturba tions can destabilize Mn3+/Mn4+ ordering and favor ferromagnetic interactio ns, resulting in large resistivity decreases connected with significant mag netization increases. The present paper reports on studies of such phenomen a, carried out in Pr0.63Ca0.37MnO3, as a function of temperature, magnetic field, or time. Combining in each case magnetization and resistivity measur ements, it is shown that the insulator-metal transitions induced by these t hree parameters can be well described by the same percolation law sigma pro portional to (f -f(c))(s), relating electric conductivity (sigma) to the fe rromagnetic fraction (f).