Mesoscopic, Non-equilibrium Fluctuations of Inhomogeneous Electronic States in Manganites

By using dark-field real-space imaging technique of transmission electron microscopy (TEM), we have observed slow 200angstroms-scale fluctuations of charge-ordered (CO) phase in mixed-valent manganites under a strong electron beam irradiation. These unusual fluctuations of the CO phase are related to the switching-type fluctuations of electrical resistivity, which were found to be as large as several percents. Systematic analysis indicates that this slow dynamics with a time scale of the order of seconds originates from non-equilibrium processes, and a metastable, charge- "disordered" insulating phase, phase, plays an essential role in the observed fluctuations.