Showing papers by "Shigeo Mori published in 2002"
TL;DR: An unusual coexistence of the CO/OO and FM metallic states with micrometer size below a MI transition temperature of 60 K is found, providing direct evidence of the phase separation found in CMR manganites.
Abstract: Magnetic domain structure in manganites was investigated by Lorentz electron microscopy, in order to understand some unusual physical properties, such as a colossal magnetoresistance (CMR) effect and a metal-to-insulator (MI) transition. In particular, we examined the spatial distribution of the charge/orbital ordered (CO/OO) insulator state and the ferromagnetic (FM) metallic state in phase-separated manganites, (La 5 / 8 - x Pr x )Ca 3 / 8 MnO 3 for x = 0.375, by obtaining both the dark-field and Lorentz images. We found an unusual coexistence of the CO/OO and FM metallic states with micrometer size below a MI transition temperature of 60 K. Our experimental findings provide direct evidence of the phase separation found in CMR manganites.
22 citations
TL;DR: In this article, the coexistence of the magnetic clusters in terms of intrinsic change separation was investigated by means of small-angle neutron scattering (SANS) and Lorentz micrograph experiments, and it was found that ferromagnetic microclusters of the order of ∼10 nm are invaded in the antiferromagnetic matrix with the G-type spin structure.
Abstract: Microscopic magnetic structures of Tb 1- x Ca x MnO 3 ( x ∼1) have been investigated by means of small-angle neutron scattering (SANS) and Lorentz micrograph experiments. We have found that ferromagnetic microclusters of the order of ∼10 nm are invaded in the antiferromagnetic matrix with the G-type spin structure. We have interpreted the coexistence of the magnetic clusters in terms of intrinsic change separation.
10 citations
TL;DR: In this article, a numerical simulation of a vertically held metal-halide lamp (Hg/Na/Sc system) was presented, driven by an ac current of 60 Hz.
Abstract: Numerical simulation of a vertically held metal-halide lamp (Hg/Na/Sc system) is presented. The lamp was driven by an ac current of 60 Hz. The model took convection and diffusion of various species into account. A method for rapid calculation of optically thick radiation power was developed. Density of scandium ions and sodium ions has a minimum on the central axis due to radial ambipolar diffusion. Density of metallic atoms and ions and metal iodine molecules decreases with increasing axial distance from the bottom of the tube. This tendency was explained by convection and diffusion. The density of scandium ions depends on the direction of the current; the density was greater at upward current than at downward current.
10 citations
TL;DR: In this article, the impurity effect on the charge and orbital ordered (CO/OO) state in doped manganites has been studied by the transmission electron microscopy (TEM), in addition to the electric and magnetic measurements.
Abstract: Impurity effect on the charge and orbital ordered (CO/OO) state in doped manganites has been studied by the transmission electron microscopy (TEM), in addition to the electric and magnetic measurements. In the Cr-doped manganites (Nd 0.5 Ca 0.5 Mn 1- y Cr y O 3 ), the CO/OO state characterized by the incommensurate wave vector is still realized as the microdomains with the size of 10–30 nm even at lower temperature of 20 K. On the other hand, the Sc-doped manganites (Nd 0.5 Ca 0.5 Mn 1- y Sc y O 3 ) clearly show an incommensurate to commensurate structural phase transition accompanying the formation of the long-ranged CO/OO state around 60 K. From our experimental findings, it is suggested that the substituted Cr 3+ and Sc 3+ ions serve as the spin impurity and hole vacancy, respectively.
7 citations