Time-dependent phenomena in phase-separated electron-doped manganites

We present time-dependent behavior of the transport and magnetic properties in electron-doped manganites. The relaxation of the electrical resistivity (ρ) shows a clear correlation with the microscopic properties of the samples observed through transmission electron microscopy. Two different relaxation mechanisms could be distinguished in La0.23 Ca0.77 MnO3. One of them was found to be common to different electron-doped manganites and is associated with a defective formation of the charge-order (CO) phase. The second one is the result of the coexistence of the CO phase with a secondary charge-disordered (CD) phase. In this case, a low-temperature boundary between static and dynamic phase-separation regimes is determined by the appearance of a small ferromagnetic moment associated with the CD volume. These results show that kinematic constraints and magnetoelastic interactions are key ingredients for a proper understanding of phase-separated manganites.