Symmetry and Nonstoichiometry as Possible Origin of Ferromagnetism in Nanoscale oxides

We show through density functional theory calculations that extended magnetic states can inherently occur in oxides as the size of the crystals is reduced down to the nanometer scale even when they do not explicitly include intrinsic defects. This is because in nanoscale systems crystallographically perfect crystallites paradoxically result in nonstoichiometric compositions owing to the finite number of constituting atoms. In these structurally perfect but stoichiometrically imperfect nanocrystallites, the spin-triplet state is found to be more stable than the spin-singlet state, giving rise to an extended spin distribution that expands over the entire crystal. According to this picture, long-range magnetic order arises from the combined effect of crystal symmetry and nonstoichiometry that can coexist exclusively in nanoscale systems. The idea can also give reasonable explanations for the unprecedented ferromagnetic features observed commonly in nanoscale oxides, including ubiquity, anisotropy, and diluteness.Comment: 12 pages, 4 figure

ワガクニ ノ キギョウ ケイエイ ノ カダイ ト テンボウ ソシキ ノ シテン オ チュウシン ニ

This paper attempted to analyze the issues and prospects of Japanese corporate management, mainly from the organization\u27s point of view. First of all, I reviewed the present situation of Japanese corporate management from a global perspective, the political and economic reality of the world, the progress of the IT revolution, and stated the difficult reality surrounding Japanese companies and the difficulties standing in the future. Next, we introduced three successful cases of corporate innovation, and summarized management issues of Japanese companies from three viewpoints: (1) paradox of success, (2) management perspective, (3) organizational perspective - “big company disease”. Finally, From a viewpoint of continuity and stability to risk taking and change，we discussed the change of corporate view, management reform, diversification of organizational view, new organizational view, and dynamism of strategy and organization. As an essential supplement, we pointed out the nature and limitations of the corporation

Metal-catalyst-free growth of silica nanowires and carbon nanotubes using Ge nanostructures

The use of Ge nanostructures is investigated for the metal-catalyst-free growth of silica nanowires and carbon nanotubes (CNTs). Silica nanowires with diameters of 10-50 nm and lengths of ? 1 ?m were grown from SiGe islands, Ge dots, and Ge nanoparticles. High-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) reveal that the nanowires grow from oxide nanoparticles on the sample surface. We propose that the growth mechanism is thermal diffusion of oxide through the GeO2 nanostructures. CNTs with diameters 0.6-2.5 nm and lengths of less than a few ?m were similarly grown by chemical vapor deposition from different types of Ge nanostructures. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. HRTEM images reveal that the CNTs also grow from oxide nanoparticles, comprising a mixture of GeO2 and SiO2

Growth of Carbon Nanotubes on HfO2 towards Highly Sensitive Nano-Sensors

Carbon nanotube (CNT) growth on HfO2 is reported for the first time. The process uses a combination of Ge and Fe nanoparticles and achieves an increase in CNT density from 0.15 to 6.2 mm length/mm2 compared with Fe nanoparticles alone. The synthesized CNTs are assessed by the fabrication of back-gate CNT field-effect transistors with Al source/drain contacts for nano-sensor applications. The devices exhibit excellent p-type behavior with an Ion=Ioff ratio of 105 and a steep sub-threshold slope of 130 mV/dec

Photochemical Reactions of Ge-Related Centers in Germanosilicate Glass Preparted by Sol-Gel Process (SOLID STATE CHEMISTRY-Amorphous Materials)

Germanosilicate glasses are prepared by a sol-gel method and the UV-photosensitivity of glasses is investigated by optical absorption, ESR, and photoluminescence measurements. Large changes in optical absorption are observed for the sol-gel-derived glass by the ultraviolet laser irradiation; a decrease in 5-eV band and increases in absorption around 4.5 and > 5.7 eV. Photoluminescence intensity under 248- nm excitation decreases with an increase in laser fluence and also with decrease in the 5-eV band. This result strongly implies the novel photochemical reaction from Ge2+ to Ge E' induced by excimer laser irradiation