Hiroko Tokoro 교수

Cyano-bridged bimetal assemblies demonstrate novel magnetic functionalities, particularly Prussian blue analogs, which have unique properties. In this perspective, we describe a charge-transfer phase transition, reversible photomagnetism, second harmonic generation and magnetization-induced second harmonic generation, ferroelectric ferromagnetism, humidity-sensitive magnetism, high ionic conductivity, and a coupling effect (which we named spin-ionics) between ionic conduction and magnetic orderi

We report on the photomagnetic effect in Rb0.91Mn1.05[Fe(CN)6]⋅0.6H2O ferromagnet. Magnetization of this system was reduced by irradiation with only one-shot of laser pulse (532 nm) at 3 K. This photodemagnetization was observed only when the laser power density (P) was above 9.3 mJ cm−2 pulse−1. The quantum yield was above one and reached 4.5 at P=43 mJ cm−2 pulse−1, showing that this phenomenon is driven by a cooperative effect such as the photoinduced domino effect. Infrared spectra before an

In a rubidium manganese hexacyanoferrate, RbMn[Fe(CN)(6)], the magnetic susceptibility (chi(M)) decreased at 225 K (=T(1/2)decreasing) and abruptly increased at 300 K (=T(1/2)increasing) in the cooling and warming processes, respectively. X-ray photoelectron spectroscopy and infrared spectroscopy indicated that the high-temperature (HT) and low-temperature (LT) phases were composed of Mn(II)-NC-Fe(III) and Mn(III)-NC-Fe(II), respectively. A structural change from cubic (F43m, a = 10.533 A) to te

The photoreversibility of a photoinduced phase transition was investigated in a rubidium manganese hexacyanoferrate, Rb0.88Mn[Fe(CN)6]0.96·0.5H2O. The present material shows a charge-transfer phase transition from the MnII−FeIII [high-temperature (HT)] phase to the MnIII−FeII [low-temperature (LT)] phase, and the LT phase shows ferromagnetism. Spectroscopic ellipsometry measurements of the dielectric constant suggest that the optical transitions in the LT and HT phases are a metal-to-metal charg

Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a

The phase transition from Fe(II)(S=0)–CN–Mn(III)(S=2) to Fe(III)(S=1∕2)–CN–Mn(II)(S=5∕2) in Rb0.98Mn1.01[Fe(CN)6]∙0.2H2O was observed at room temperature with a one-shot-laser-pulse (λ=532nm; pulse width: 6ns) irradiation. The quantum yield (Φ) depended on the laser power density (P) and Φ=38 was achieved with a 24mJcm−2pulse−1. In this photochemical reaction, only when the P value was above 6mJcm−2pulse−1 (Pth), the low-temperature phase was converted to the high-temperature phase. The threshol

The charge-transfer phase transition in ${\mathrm{Rb}}_{0.64}^{\mathrm{I}}{\mathrm{Mn}}^{\mathrm{II}}[{\mathrm{Fe}}^{\mathrm{III}}(\mathrm{CN}{)}_{6}{]}_{0.88}∙1.7{\mathrm{H}}_{2}\mathrm{O}$ exhibits a surprisingly large thermal hysteresis loop of $138\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, i.e., the phase transition temperatures are $165\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ $(={T}_{1∕2\ensuremath{\downarrow}})$ and $303\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ $(={T}_{1∕2\ensuremath{\uparrow}})$.

Abstract Epsilon iron oxide (ε-Fe2O3) is attracting global attention as a magnetic material with a large magnetic anisotropy. In this article, the optical properties of ε-Fe2O3 nanoparticles and the metal-substituted series of ε-MxFe2−xO3 (M = Ga, In, and Al) are studied over a wide frequency range from the millimeter-wave to terahertz-wave region, 30 GHz–30 THz, using terahertz time-domain, far-infrared, and Raman spectroscopies. To understand the spectroscopic data, first-principles calculatio

A zero thermal expansion (ZTE) material based on plate-shaped rubidium manganese hexacyanoferrate, Rb0.97Mn[Fe(CN)6]0.99·0.3H2O, is prepared using a polyethylene glycol monolaurate (PEGM) surfactant matrix. The prepared microcrystals show a charge transfer induced phase transition between the cubic MnII–NC–FeIII and tetragonal MnIII–NC–FeII phases. The MnIII–NC–FeII phase exhibits a small negative thermal expansion (NTE) along the aLT and cLT axes with a thermal expansion coefficient of α(aLT) =