Phase separation and ferromagnetic microdomains in doped manganites

Manganites with the perovskite structure exhibit a variety of unusual physical properties such as a colossal magnetroresistance (CMR) and a metal to insulator (MI) transition. Recent theoretical and experimental studies pointed out that the spatial inhomogeneous state of magnetic, electric and/or lattice systems, which is characterized as phase separation, is important to understand unusual physical properties in the doped-manganites.[l] Recently it was found that, by substituting Cr ions for the Mn ones in doped-manganites, the long-ranged charge and orbital ordered (CO) state becomes short-ranged one and new ferromagnetic (FM) metallic state is induced.[2] In addition, Kimura et al. found that the impurity-doped manganites (Ndo.sCao.SMnl-yCry03) show characteristic physical properties similar with relaxor ferroelectrics such as Pb(NbI/3Mg2l3)03. [3] These anomalous properties found in the impurity-doped manganites have close relation to spatially inhomogeneous state of the FM state and the CO one. Here we reported structural change related to the anomalous properties found in the impurity-doped manganites.[4] In particular, we investigated the microstructure related to both the CO state and the FM one with a spatial resolution of ~nm by means of both the transmission electron microscopy and low-temperature Lorentz microscopy. The magnetic and electric properties in the impurity-doped Ndo.sCao.SMn03 were shown i