Shin‐ichi Ohkoshi 교수

We show the design and preparation of a novel type of magnet exhibiting two compensation temperatures; i.e., the spontaneous magnetization changes its sign twice with changing temperature. The key to obtaining this unusual behavior is the simultaneous incorporation of one antiferromagnetic and two different ferromagnetic interactions through the use of four different spin sources, as predicted by a calculation based on molecular field theory. As a prototype exemplifying this idea, we have prepar

The study of photoinduced phase-transition materials has implications for the fields of inorganic chemistry, solid-state chemistry, and materials science. Cyano-bridged bimetal assemblies are promising photomagnetic materials. Because cyano-bridged bimetal assemblies possess various absorption bands in the visible light region, their electronic and spin states can be controlled by visible light irradiation. Moreover, the selection of magnetic metal ions and organic ligands provide a way of contr

We have succeeded in controlling the saturation magnetization ${(I}_{S}),$ the Weiss temperature (\ensuremath{\theta}), and the coercive field ${(H}_{c})$ using compounds in the series $({\mathrm{Ni}}_{x}^{\mathrm{II}}{\mathrm{Mn}}_{1\ensuremath{-}x}^{\mathrm{II}}{)}_{1.5}{[\mathrm{Cr}}^{\mathrm{III}}(\mathrm{C}\mathrm{N}{)}_{6}]$ as model compounds. The key to this strategy is to manipulate both ferromagnetic $(J>0)$ and antiferromagnetic $(J<0)$ exchange interactions by incorporating the

Multiferroic material: RbI0.82MnII0.20MnIII0.80[FeII(CN)6]0.80[FeIII(CN)6]0.14⋅H2O (see picture; MnII red octahedra, FeIII red spheres, MnIII blue octahedra, FeII blue spheres, CN white lines, gaps are Fe vacancies; H2O omitted) displays both ferroelectricity, explained by a mixing of FeII, FeIII, Fe vacancies, MnII, and Jahn–Teller-distorted MnIII centers, and ferromagnetism, caused by a parallel ordering of the magnetic spins of MnIII.

This article describes the studies of a photomagnetic cyanide-bridged Cu-Mo bimetallic assembly, Cu(II)(2)[Mo(IV)(CN)(8)].8H(2)O (Cu(II), S = (1)/(2); Mo(IV), S = 0) (1), which has an intervalence transfer (IT) band from Mo(IV)-CN-Cu(II) to Mo(V)-CN-Cu(I) around 480 nm. Wide-angle X-ray scattering and X-ray spectroscopic studies provide precise information about the 3D connectivity and the local environment of the transition metal ions. Irradiating with blue light causes solid 1 to exhibit a spo

We observed high proton conductivities of 1.2 x 10(-3) and 1.6 x 10(-3) S cm(-1) on Co[Cr(CN)(6)](2/3).zH(2)O and V[Cr(CN)(6)](2/3).zH(2)O, respectively, and an interference effect between magnetic ordering and ionic conduction below the magnetic phase transition temperature.

We tried to design the magnet exhibiting magnetic pole (N and S) inversion by photostimuli. The magnetization of Fe1.5IICrIII(CN)6⋅7.5H2O was changed in a photon mode by visible light. A ferro-ferrimagnet (Fe0.40IIMn0.60II)1.5CrIII(CN)6⋅7.5H2O mixed by ferromagnetic (Fe–Cr system showing the change of magnetization by optical stimuli) site and ferrimagnetic (Mn–Cr system showing no optical response) site showed negative magnetization at the temperature lower than compensation temperature (Tcomp=

Restraining electromagnetic interference in the millimeter-wave region has been accomplished with a new electromagnetic absorber composed of ε-GaxFe2−xO3 (0.10≤x≤0.67) nanomagnets, which shows a ferromagnetic resonance in the range 35–147 GHz. The possibility that the ferromagnetic resonance can achieve a frequency of 190 GHz at x→0 is also suggested. See picture: Hc=coercive field; fr=ferromagnetic resonance frequency. Electromagnetic (EM) waves in the millimeter wave range (30–300 GHz) are beg

A three-dimensional magnetic material [{CoII(pyrimidine)(H2O)}2{CoII(H2O)2}{WV(CN)8}2](pyrimidine)2. 2H2O is prepared. This compound exhibits a charge-transfer-induced spin transition with a large thermal hysteresis loop of 90 K. Irradiating with light causes the low-temperature phase to exhibit a spontaneous magnetization with a Curie temperature of 40 K and a magnetic hysteresis loop with a coercive field of 12 000 G, which is the highest value reported for a photomagnet. The observed photoind

We show a novel magnetic phenomenon, “photoinduced magnetic pole inversion”, which occurs even in the absence of an external magnetic field. The key of this strategy is to control the compensation temperature by a pure photoprocess. Here, we combined two magnetic behaviors which were developed recently. One of them is the photoinduced change of magnetization for some of the Prussian blue analogues. The other is a so-called mixed ferro-ferrimagnetism in the system of ternary metal Prussian blue a