67Ca0.33MnO3 [41]. A dubbed CMR, this effect arises because the applied magnetic field drives a phase transition from an insulating paramagnet to a spin-aligned metal. Thus, as Jonker and van Santen reduced the temperature to reach the conducting spin-aligned phase, Jin and his colleagues applied a magnetic field. Recently, Woodward et al. performed a neutron diffraction study of Nd0.5Sr0.5MnO3 and found that this material first became FM at 250 K, partially transforming to an A-type AFM phase at approximately 220 K, followed by a transformation of a substantial fraction to a CE-type AFM phase at

approximately 150 K [42]. Their experimental results indicate that three phases (FM metallic and CE-AFM charge-ordered phases along with an A-type AFM phase) coexist at low temperatures, and the size scale of the Erlotinib ic50 inhomogeneities is at least in the mesoscopic range (a few hundred nanometres or more). Sub-micrometersized phase separation find more involving FM and charge-ordered AFM domains with a typical size of about 0.2 μm was found in La0.625-y Pr y Ca0.375MnO3 by transmission electron microscopy (TEM) [5]. At the same time, by using scanning tunneling spectroscopy (STM), Fäth et al. also found the evidence of electronic inhomogeneities in La0.7Ca0.3MnO3 below the FM

transition temperature with a mesoscopic scale of about 0.2 μm, where the FM metallic domains are interspersed in insulating regions [43]. Mesoscopic phase separation with the length scale between 30 and 200 nm, arising from the comparable energies of the ferromagnetic metallic and antiferromagnetic insulating states, is just one extreme in the perovskite manganites [5]. Normally, the EPS with phases of different

charge densities is expected to give rise to nanometer scale clusters because large phase separated domains would break up into small pieces due to the Coulomb interactions. For example, Mori et al. reported a nanoscopic length scale of the electronic inhomogeneity of in thin films of the hole-doped side of (La,Ca)MnO3 by high-resolution TEM [44]. Similarly, in Bi0.25Ca0.75MnO3, Renner et al. also found nanoscopic charge-ordered and metallic domains which were correlated with the structural distortions [45]. Generally, microscopically homogeneous clusters are usually in the diameter size of 1 to 2 nm dispersed in an insulating or charge-localized matrix. For example, recently, De Teresa et al. [46] reported on the experimental evidence for the existence of nanoscopic phase segregation in the manganite compounds of (La1-x A x )2/3Ca1/3MnO3 (A = Y or Tb), in which the spontaneous formation of localized magnetic clusters with size of ~1.2 nm above the ferromagnetic ordering temperature was revealed by a combination of volume thermal expansion, magnetic susceptibility, and small-angle neutron scattering measurements.