[en] We analyze the three-dimensional axial next-nearest-neighbor Ising model composed of two kinds of alternately stacked ferromagnetic layers with different intralayer interactions by using Monte Carlo (MC) simulation. The detailed analyses of the magnetization and the spin correlations perpendicular to the stacked direction, assure and clarify the existence and the nature of the paramagnetic layers in some modulated phases with wave numbers, 1/4, 1/8, 3/16. This is the first MC confirmation of the partially disordered states which have been predicted by previous molecular field calculation and/or observed in materials such as CsCoCl₃, CuFeO₂ and CeSb

[en] We consider an extended 3-d axial next-nearest-neighbor Ising model, which is composed of two kinds of alternately stacked ferromagnetic layers with different intralayer interactions. Monte Carlo simulation is performed on L³ simple cubic lattice (L=20-80). Since a minimum of the fourth-order energy cumulant(V_L), which corresponds to phase transition to partially disordered phase, reaches the value very close to ((2)/(3)) as L→∞, we conclude that this phase transition is second order. From the finite-size scaling analysis of V_L and specific heat, we estimate the critical exponents

[en] The magnetization of spin S(=((1)/(2)) and 1) Ising systems with bilinear and four-site four-spin interactions has been investigated by making use of the Monte Carlo simulation. In low-temperature region, the magnetization curves show an anomalous inverse inclination and decrease (increase) with the decrease (increase) of temperature within a certain exchange ratio range. The relation between the value of the magnetization at zero-temperature and the spin structure expected for the ground state is discussed

[en] The magnetization, the specific heat and the Curie temperature of the Ising spin system with two-spin and four-spin interactions have been investigated by making use of the Monte Carlo simulation. In low temperature region, the magnetization and the specific heat curves show different characteristic behaviors for the three-site four-spin interaction and the four-site four-spin interaction

[en] Hokkaido Electric Power Company. Inc is constructing 3-loop PWR named TOMARI-3 at TOMARI-mura, Hokkaido. Although basic design is almost same as existent 3-loop PWR, there are some improvements in thermal hydraulic design for a plant performance. Core bypass flow is increased to keep equipment integrity for a long time. Plant safety is confirmed by DNB analysis with this change. (author)

[en] The lichen Trapelia involuta from uraniferous spoil heaps in Cornwall, England, growing directly on the secondary uranium minerals, metazeunerite and metatorbernite, was examined by field-emission scanning electron microscopy and transmission electron microscopy to assess the effect of Trapelia on uranium migration. We observed metazeunerite, sericite and scorodite as well as unidentified Fe-, Pb/As-, Fe/As-, Al/P-, Pb-bearing minerals concentrated in the lichen exciple and medulla. In addition, metazeunerite also occurred in the epithecium. The chemistries, sizes, and occurrences of the above minerals in the lichen suggest that fixation of U as well as Pb, As, Fe, and Al is dependent on lichen physiological processes. We suggest Trapelia accumulates these elements from groundwater and precipitates the above minerals within specific tissues. Our results indicate that some lichens retard uranium migration by accumulating uranium from groundwater and forming uranium-bearing minerals within their tissues. Copyright (2001) Material Research Society

[en] Core-shell GaN nanowires are expected to be building blocks of future light emitting devices. Here we apply off-axis electron holography to map the electrostatic potential distributions in such nanowires. To access the cross-section of selected individual nanowires, focused ion beam (FIB) milling is used. Furthermore, to assess the influence of FIB damage, the dopant potential measured from an intact NW is compared with a FIB prepared one. It is shown that in addition to the built-in potential between the p-type shell and unintentionally n-type under-layer there is a potential barrier between the core and under-layer which are both unintentionally n-type doped

[en] The spin fluctuation effect on the appearance of plural compensation temperatures in ferrimagnet is studied for a simple mixed ferro-ferrimagnetic ternary alloy model of the type AX(X=B_pC_1-p) on a decorated lattice consisting of three kinds of magnetic ions A, B and C. The combination of molecular field approximation, decorated-iteration transformation and the Monte Carlo simulation enabled us to discuss systematically the effect of inclusion of spin fluctuation and also showed a possibility to discuss the effect of spin fluctuation and that of concentration distribution separately

[en] We use density functional theory to explore the effect on calculations of semiconductor mean inner potentials of the presence of reconstructions, changes in lattice spacing and adsorbates on the surfaces of parallel-sided thin specimens. We also use electron holography to illustrate several factors that affect experimental measurements of mean inner potentials of semiconductor nanowires.

[en] In order to investigate the reproducibility of measurements of transmission electron microscope detector modulation transfer functions (MTFs) we measure the MTF of a charge-coupled device (CCD) camera using five different methods. MTFs derived from a sharp edge, a circular aperture and electron holographic interference fringes are found to agree closely with one other. The difficulty of obtaining accurate measurements of MTFs and the potential of using focused electron probes to make direct measurements of MTFs is discussed. We highlight the sensitivity of image contrast after deconvolution to small differences in the measured MTF. - Highlights: ► The modulation transfer function (MTF) of a CCD camera is measured using five different methods. ► Only methods that involve the use of a sharp aperture or holographic interference fringes work well. ► The use of a focused spot promises to be the best method in the future if it can be focused small enough. ► Apparently small errors in the measurement of the MTF can have a large effect on deconvoluted images. ► MTFs must be measured accurately if images are to be compared quantitatively with simulations