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The two-dimensional organic superconductor $\ensuremath{\lambda}\ensuremath{-}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ exhibits pronounced charge fluctuations below $T\ensuremath{\approx}150$ K, in contrast to the sibling compound $\ensuremath{\kappa}\ensuremath{-}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ that remains metallic down to milli-Kelvin. Infrared spectroscopy reveals only minor splitting in the vibrational features of the latter compound, common to other strongly dimerized $\ensuremath{\kappa}$-type salts. When the organic molecules are arranged in the $\ensuremath{\lambda}$-type pattern, however, a strong vibrational ${\ensuremath{\nu}}_{27}({b}_{1u})$ mode is present that forms a narrow doublet. Most important, when cooling $\ensuremath{\lambda}\ensuremath{-}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ below 150 K, two weak side modes appear due to charge disproportionation that amounts to $2\ensuremath{\delta}=0.14e$. In analogy to the ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-type organic conductors, we propose that charge fluctuations play an important role in emerging of unconventional superconductivity in $\ensuremath{\lambda}\ensuremath{-}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ at ${T}_{c}=4.7$ K. We discuss the possibility of a charge-density wave that coexists with the proposed spin-density-wave state.

In this work, the thermodynamic properties of the organic superconductor $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ are investigated to study a high-field superconducting state known as the putative Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. We observed a small thermodynamic anomaly in the field ${H}_{\mathrm{FFLO}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}10$ T, which corresponds to the Pauli limiting field ${H}_{\mathrm{P}}$. This anomaly probably originates from a transition from a uniform superconducting state to the FFLO state. ${H}_{\mathrm{FFLO}}$ does not show a strong-field angular dependence due to a quasi-isotropic paramagnetic effect in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$. The thermodynamic anomaly at ${H}_{\mathrm{FFLO}}$ is smeared out. and the low-temperature upper critical field ${H}_{\mathrm{c}2}$ changes significantly if fields are not parallel to the conducting plane, even for a deviation of $\ensuremath{\sim}0.{5}^{\ensuremath{\circ}}$. This behavior indicates that the high-field state is very unstable, as it is influenced by the strongly anisotropic orbital effect. Our results are consistent with the theoretical predictions on the FFLO state and show that the high-field superconductivity is probably an FFLO state in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ from a thermodynamic point of view.

We performed $^{13}\mathrm{C}$ NMR measurements on an organic superconductor $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{B}\mathrm{E}\mathrm{T}\mathrm{S})}_{2}\mathrm{Ga}{\mathrm{Cl}}_{4}$ [BETS: bis(ethylenedithio)tetraselenafulvalene] to investigate the pressure effect on the spin density wave (SDW) fluctuations at low temperatures, which were observed at ambient pressure. We found that the spin-lattice relaxation rate divided by temperature $(1/{T}_{1}T)$ is significantly enhanced at low temperatures at 3 kbar, implying enhancement of the SDW fluctuation. When further pressure is applied, increase in $1/{T}_{1}T$ at low temperatures is suppressed and $1/{T}_{1}T$ becomes temperature independent, indicating the Fermi liquid state. Moreover, we revealed that the Korringa factor under pressure becomes double compared to its value at ambient pressure, suggesting a significant change in electron correlation. We discuss the effect of the SDW fluctuation and the electron correlation on the unconventional superconductivity.

We performed angular and temperature-dependent electron-spin-resonance measurements in the quasi-two-dimensional organic conductor $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{I}$. The interlayer spin diffusion is much weaker compared to the Cl and Br analogs, which are antiferromagnetic insulator and paramagnetic metal, respectively; $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{CN})}_{2}]\mathrm{I}$ behaves insulating when cooled below $T=200\phantom{\rule{4pt}{0ex}}\mathrm{K}$. A spin gap ($\mathrm{\ensuremath{\Delta}}\ensuremath{\approx}18\phantom{\rule{4pt}{0ex}}\mathrm{K}$) opens at low temperatures leading to a spin-singlet state. Due to intrinsic disorder a substantial number of spins ($\ensuremath{\sim}1%$) remains unpaired. We observe additional signals below $T=4\phantom{\rule{4pt}{0ex}}\mathrm{K}$ with a pronounced anisotropy indicating the presence of local magnetic moments coupled to some fraction of those unpaired spins.

For the unconventional organic superconductor $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ [BETS = bis(ethylenedithio) tetraselenafulvalene], the importance of both spin and charge degrees of freedom has been discussed based on the broadening of the NMR linewidth due to charge disproportionation and the occurrence of a spin-density-wave phase near the superconducting phase. NMR with the nuclear spin of $1/2$, previously used for studying organic conductors, is an effective method for revealing electronic states microscopically; however, it cannot distinguish between charge and spin anomalies. To resolve this problem, in this paper, we performed $^{69,71}\mathrm{Ga}$-NMR measurements, which enabled us to study both charge and spin dynamics using different gyromagnetic ratios and quadrupole moments between two isotopes. The spin-lattice relaxation rate is dominated by electric-field gradient fluctuations originating from molecular dynamics above 150 K and, below this temperature, it is dominated by spin fluctuations derived from the $\ensuremath{\pi}$ electrons of BETS layers. This change in the relaxation mechanism is considered to be due to the development of interactions between ${\mathrm{GaCl}}_{4}$ ions and BETS layers upon freezing of the molecular motion by cooling. Below 150 K, the contribution of spin fluctuations monotonically increases, and no increase in the charge fluctuation was observed, suggesting that the spin degree of freedom plays a major role in low-temperature physical properties. Our findings will aid theoretical studies on superconducting properties.

We performed $^{13}\mathrm{C}$-NMR measurements on an organic superconductor $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ to investigate the superconducting (SC) gap symmetry, where BETS stands for bis(ethylenedithio)tetraselenafulvalene. As the temperature approaches 0 K, the Knight shift in the SC state decreases; the nuclear spin-lattice relaxation rate $1/{T}_{1}$ shows cubic temperature dependence below the SC transition temperature ${T}_{c}$ without a coherence peak. These results can be understood in terms of $d$-wave superconductivity. Moreover, an increase in $1/{T}_{1}T$ at lower temperatures was observed just above ${T}_{c}$; this behavior can be interpreted as an effect of spin-density-wave (SDW) fluctuation. We suggest that the $d$-wave superconductivity of $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ originates from SDW fluctuation.

We have performed $^{13}\mathrm{C}$ NMR measurements on $\ensuremath{\lambda}\ensuremath{-}{(\mathrm{BEDT}\ensuremath{-}\mathrm{STF})}_{2}{\mathrm{FeCl}}_{4}$ to reveal the mechanism of unconventional paramagneticlike behavior observed in $\ensuremath{\lambda}$-type molecular $\ensuremath{\pi}\ensuremath{-}d$ systems. $^{13}\mathrm{C}$ NMR spectra and nuclear spin-lattice relaxation rate $1/{T}_{1}$ revealed that the $\ensuremath{\pi}$ and $3d$ electron systems undergo an antiferromagnetic transition simultaneously at 16 K with the assistance of the $\ensuremath{\pi}\ensuremath{-}d$ interaction. We found that the sublattice magnetizations of the $\ensuremath{\pi}$ and $3d$ spins show different temperature dependence below ${T}_{\mathrm{N}}$, which is derived from the magnetic coupling between the two sublattice systems with different magnetic natures. We discuss the relationship between the two different magnetization processes and the unconventional magnetic behavior in $\ensuremath{\lambda}$-type molecular $\ensuremath{\pi}\ensuremath{-}d$ system.

Optical studies of the density wave (DW) salt of $\ensuremath{\alpha}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{KHg}(\mathrm{SCN})}_{4}$ revealed a pseudogap due to a charge fluctuation below ${T}^{*}\ensuremath{\simeq}$ 200 K. Moreover, $^{13}\mathrm{C}$-NMR studies of the DW salt of $\ensuremath{\alpha}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{RbHg}(\mathrm{SCN})}_{4}$ and of the superconductivity (SC) salt of $\ensuremath{\alpha}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{NH}}_{4}\mathrm{Hg}{(\mathrm{SCN})}_{4}$ suggested that the NMR line width of the A site increased and the charge disproportionation in the A column developed below ${T}^{*}$. These phenomena may be due to the development of a horizontal stripe modulation of the local charge density. However, whether the horizontal stripe modulation develops or not and the relationships among ${T}^{*}$ anomalies, the pseudogap, and line broadening, were unclear. In this study, $^{13}\mathrm{C}$-NMR measurements were obtained of the metallic salt of $\ensuremath{\alpha}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{TlHg}(\mathrm{SeCN})}_{4}$, and its electronic structure was compared with those of the DW and SC salts. The NMR line width of the A site and ${\ensuremath{\chi}}_{\mathrm{B}}/{\ensuremath{\chi}}_{\mathrm{C}}$ in Rb(SCN) and $\mathrm{NH}{}_{4}$(SCN) increased and deviated from that in Tl(SeCN) below ${T}^{*}$, suggesting the development of the instability of horizontal stripe modulation in Rb(SCN) and $\mathrm{NH}{}_{4}$(SCN) and that ${T}^{*}$ anomalies could be due to the instability.

The physical properties of the organic conductor $\ensuremath{\kappa}\text{\ensuremath{-}}(\mathrm{BEDT}\text{\ensuremath{-}}{\mathrm{TTF})}_{2}{\mathrm{Cu}[\mathrm{N}(\mathrm{CN})}_{2}]\mathrm{I}$ $(\ensuremath{\kappa}\text{\ensuremath{-}}\mathrm{I})$ are inconsistent with the universal phase diagram of isostructural $\ensuremath{\kappa}$-Br and $\ensuremath{\kappa}$-Cl. To systematically understand $\ensuremath{\kappa}$-type salts, we measured and compared $^{13}\mathrm{C}$ NMR spectra of $\ensuremath{\kappa}$-I, $\ensuremath{\kappa}$-Br, and $\ensuremath{\kappa}$-Cl. The $\ensuremath{\kappa}$-I spectra manifested abrupt line broadening below 40 K due to the development of electronic inhomogeneity and an increase in the spin-lattice relaxation rate divided by temperature $1/{T}_{1}T$ down to the lowest temperature, suggesting an enhanced antiferromagnetic (AF) fluctuation. These results imply that AF fluctuation without long-range order in $\ensuremath{\kappa}$-I is induced by electronic inhomogeneity, which disturbs the development of coherency. Consequently, $\ensuremath{\kappa}$-I is an insulator with AF fluctuation at low temperature similar to x-ray-irradiated $\ensuremath{\kappa}$-Cl. We suggest that not only pressure but also disorder is a key parameter in the physical properties of $\ensuremath{\kappa}$-type salts.

An electron paramagnetic resonance study for an organic superconductor ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{4}[({\mathrm{H}}_{3}\mathrm{O})\mathrm{Ga}{({\mathrm{C}}_{2}{\mathrm{O}}_{4})}_{3}]\phantom{\rule{0.16em}{0ex}}\ifmmode\cdot\else\textperiodcentered\fi{}\phantom{\rule{0.16em}{0ex}}{\mathrm{C}}_{6}{\mathrm{H}}_{5}{\mathrm{NO}}_{2}$ reveals that superconductivity coexists uniformly with the charge ordered state in one material. In the charge ordered state, the interplane spin exchange is gapped, while the in-plane conductivity is not significantly modified. This anisotropic behavior is explained by an exotic charge ordered state, in which molecular-site-selective carrier localization coexists with conducting carriers on other molecules. The relationship between superconductivity and this conductive charge ordered state is investigated.

Elucidation of the mechanism by which the shape of bones is formed is essential for understanding vertebrate development. Bones support the body of vertebrates by withstanding external loads, such as those imposed by gravity and muscle tension. Many studies have reported that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that bone shape adapts to external load. In fact, by simulating this relationship through topology optimization, the internal trabecular structure of bones can be successfully reproduced, thereby facilitating the study of bone diseases. In contrast, there have been few attempts to simulate the external structure of bones, which determines vertebrate morphology. However, the external shape of bones may be reproduced through topology optimization because cells of the same type form both the internal and external structures of bones. Here, we constructed a three-dimensional topology optimization model to attempt the reproduction of the external shape of teleost vertebrae. In teleosts, the internal structure of the vertebral bodies is invariable, exhibiting an hourglass shape, whereas the lateral structure supporting the internal structure differs among species. Based on the anatomical observations, we applied different external loads to the hourglass-shaped part. The simulations produced a variety of three-dimensional structures, some of which exhibited several structural features similar to those of actual teleost vertebrae. In addition, by adjusting the geometric parameters, such as the width of the hourglass shape, we reproduced the variation in the teleost vertebrae shapes. These results suggest that a simulation using topology optimization can successfully reproduce the external shapes of teleost vertebrae. By applying our topology optimization model to various bones of vertebrates, we can understand how the external shape of bones adapts to external loads., Author summary In this paper, we developed a computational method to investigate the relationship between three-dimensional bone shape and external loads imposed on bones. Many studies report that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that the shape of bones adapts to external load. However, it remains unclear whether this hypothesis can explain the shape of bones. Here, we constructed a three-dimensional mathematical model that imitates the cellular activities of bone formation to attempt the reproduction of the shape of teleost vertebrae. In teleosts, the shape of the vertebrae differs among the species. We set the multiple types of external load conditions in the simulations and compared the simulation results with different teleost vertebrae. The produced structures that can resist the deformation of the surrounding tissues exhibited multiple structural features similar to the vertebrae of several teleost species. This result shows that the formation of bone shape can be explained by the adaptation to external load.

We have performed $^{1}\mathrm{H}$ NMR and $^{13}\mathrm{C}$ NMR measurements to investigate the coupling between molecular dynamics and the electronic state of ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)${}_{2}{\mathrm{ICl}}_{2}$. From the $^{1}\mathrm{H}$ NMR measurements, we observed a frequency-dependent anomaly in the nuclear spin-lattice relaxation rate $^{1}\mathrm{T}_{1}^{\ensuremath{-}1}$ that originates from the slowing down of the ethylene motion. In the $^{13}\mathrm{C}$ NMR measurements, we found an anomaly in the linewidth of the NMR spectra at around 150 K, which is attributed to a nuclear spin-spin relaxation rate $(^{13}\mathrm{T}_{2})$ anomaly. The magnitudes of the anomalies in the linewidth and in $^{13}\mathrm{T}_{2}^{\ensuremath{-}1}$ are related to the hyperfine coupling constant. These results suggest that the ethylene motion modulates the molecular orbital of the BEDT-TTF molecules and gives rise to a difference in the orbital energy between the ``staggered'' and ``eclipsed'' conformations. We propose that significant coupling exists between the ethylene motion and the electronic state of the molecular dimer and that the ethylene dynamics can trigger the emergence of charge degrees of freedom inside the dimers and cause the dielectric anomaly in ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)${}_{2}{\mathrm{ICl}}_{2}$.

We performed $^{13}\mathrm{C}$ NMR measurements on the unconventional organic superconductor $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ to clarify its electronic properties in the paramagnetic state. We found that the spin-lattice relaxation rate divided by temperature $1/{T}_{1}T$ shows Curie-like enhancement above 55 K that arises from an antiferromagnetic fluctuation. In addition, we found additional enhancement of $1/{T}_{1}T$ below 10 K, where the Knight shift decreases and the linewidth of NMR spectra is broadened. The result could be understood by the magnetic fluctuation induced by the nesting of the Fermi surface. We discovered that $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BETS})}_{2}{\mathrm{GaCl}}_{4}$ salt inherently exhibits the two different types of magnetic fluctuations.

We present the results of $^{13}\mathrm{C}$ NMR experiments in an organic superconductor with localized Fe spins ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}{(\text{BEDT-}\mathrm{TTF})}_{4}[({\mathrm{H}}_{3}\mathrm{O})\mathrm{Fe}{({\mathrm{C}}_{2}{\mathrm{O}}_{4})}_{3}]\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{C}}_{6}{\mathrm{H}}_{5}\mathrm{Br}$. We reveal the antiferromagnetic coupling between Fe $d$ spins and $\ensuremath{\pi}$ spins, which creates an exchange field antiparallel to the external field direction at the $\ensuremath{\pi}$ electrons. In addition to the static effects of Fe spins, we show from the nuclear spin-lattice relaxation rate measurement that the magnetic fluctuations generated by Fe spins are suppressed at low temperatures and high magnetic fields. These conditions are suitable to stabilize the field-induced superconductivity by the field compensation mechanism. After the suppression of Fe-spin dynamics by a magnetic field of 19 T, we observed the underlying $\ensuremath{\pi}$-electron contribution. We discuss a possible anomaly in the $\ensuremath{\pi}$-electron system.

We performed $^{13}\mathrm{C}$-NMR experiment and measured spin-lattice relaxation rate divided by temperature $1/{T}_{1}T$ near the superconducting (SC) transition temperature ${T}_{c}$ in $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu[N(CN)${}_{2}$]Br ($\ensuremath{\kappa}$-Br salt), and $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu(NCS)${}_{2}$ ($\ensuremath{\kappa}$-NCS salt). We observed the reduction of $1/{T}_{1}T$ starting at the temperature higher than ${T}_{c}$ in $\ensuremath{\kappa}$-Br salt. Microscopic observation of the quasiparticle density of states in the fluctuating SC state revealed the effects of short-range Cooper pairs induced in the normal state to the quasiparticle density of states. We also performed systematic measurements in the fields both parallel and perpendicular to the conduction plane in $\ensuremath{\kappa}$-Br and $\ensuremath{\kappa}$-NCS salts, and confirmed that the reduction of $1/{T}_{1}T$ above ${T}_{c}$ is observed only in $\ensuremath{\kappa}$-Br salt regardless of the external field orientation.

In recent years, concern has been raised about the charge fluctuation of the superconducting transition in the loosely dimerized molecular conductors. Not only the observation of the charge fluctuation is of considerably important but also the understanding of the mechanism of the fluctuation. We have observed degree of charge fluctuation of several β''-type ET salts. The β''-type ET salt is one of the best model compounds because the direction of the largest inter-site Coulomb interaction is perpendicular to that of the largest transfer integral. This structural property allows us to examine the role of inter-site Coulomb interaction from the viewpoint of the inter-molecular distance. The difference in the molecular charges between the charge rich site and the charge poor sites, Δρ, is correlated with the conducting behavior; the superconducting materials have the small but finite Δρ, whereas Δρ of the insulating (metallic) materials is large (almost zero). After the analysis of the configuration in the inter-molecular distances, we have found that the degree of fluctuation, Δρ, is attributed to the number of the most stable charge distribution(s), NS, and the number of the energy levels of the allowed charge distribution, NA. The superconducting materials belong to the condition of N ≥2 and N ge;2. Indeed, this condition contributes to the fluctuation of the molecular charges. © 2010 Elsevier B.V. All rights reserved.

The electronic specific heat of partially deuterated organic conductors $\ensuremath{\kappa}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{Cu}[\mathrm{N}(\mathrm{CN})}_{2}]\mathrm{B}\mathrm{r},$ [where BEDT-TTF denotes bis(ethylenedithio)tetrathiafulvalene], which are situated around the critical boundary of a metal-insulator transition in two dimensions, are studied. It was found that when the system has access to the $M\ensuremath{-}I$ boundary with the progressive deuteration of BEDT-TTF molecules, the normal-state \ensuremath{\gamma} term diminishes. The absence of mass enhancement is marked as a basis for the future study of electronic features related to the nature of superconductivity and also on the universality and variation of a possible Mott transition in two-dimensional systems.

Zero-field μSR measurements on the antiferromagnetic Mott insulator β ′-(BEDT-TTF) 2 ICl 2 were performed in order to study the microscopic magnetic properties of this organics. The volume fraction of the antiferromagnetic phase was found to be temperature independent. Muon precession frequency, which is proportional to the magnitude of the magnetic moment at the dimer of two BEDT-TTF molecules, does not follow the simple model based on the mean-field approximation.

Quasi-one-dimensional organic conductors (TMT$C$F)${}_{2}$$X$ have various electric and magnetic properties. Although theoretical and experimental studies have suggested that (TMTTF)${}_{2}$Br has the properties of commensurate antiferromagnetism, details of the magnetic structure of this compound are unclear. Two types of antiferromagnetism are expected, one due to a localized electron and the other to the nesting of the Fermi surface. We therefore assessed the antiferromagnetic structure of (TMTTF)${}_{2}$Br using ${}^{13}$C NMR. Site assignment of the observed antiferromagnetic spectrum confirmed that there were two magnetic molecular sites, with staggered moments and amplitude of 0.11${\ensuremath{\mu}}_{B}$/molecule, as well as nonmagnetic molecular sites. A commensurate structure with antiferromagnetic ordering of ($\ensuremath{\uparrow}\ensuremath{\circ}\ensuremath{\downarrow}\ensuremath{\circ}$) along a one-dimensional chain would be expected as the freezing of antiferromagnetic fluctuations in the charge-ordered phase of the (TMTTF)${}_{2}$AsF${}_{6}$ salt. The presence of a nodal site is strongly suggestive of the nesting type antiferromagnetism. The fine structure of the antiferromagnetic spectrum suggests superlattice along the interchain direction. We could not observe line broadening due to the charge order above the antiferromagnetic transition.

A spin-density-wave (SDW) for $(\mathrm{TMTSF})_{2}\mathrm{PF}_{6}$ has been reported to appear below ${T}_{\mathrm{SDW}}$ ($\ensuremath{\simeq}12\text{ }\text{ }\mathrm{K}$), with a subphase transition at ${T}^{*}$ ($\ensuremath{\simeq}4\text{ }\text{ }\mathrm{K}$). To determine the structure of the subphase, we synthesized $(\mathrm{TMTSF})_{2}\mathrm{PF}_{6}$, in which one side of the central carbon bond in each TMTSF molecule was replaced by $^{13}\mathrm{C}$, and utilized this compound in $^{13}\mathrm{C}$ nuclear magnetic resonance measurements. Below ${T}_{\mathrm{SDW}}$, the spectrum became broad and ${T}_{1}^{\ensuremath{-}1}$ decreased, in agreement with previous results. Below ${T}^{*}$, fine structures emerged in the center of the spectrum and ${T}_{1}^{\ensuremath{-}1}$ decreased exponentially. These phenomena were attributed to the emergence of commensurability at ${T}^{*}$.

To explore the connection between $\ensuremath{\alpha}$-(BEDT$\ensuremath{-}$TTF)${}_{2}$I${}_{3}$ and $\ensuremath{\alpha}$-(BEDT$\ensuremath{-}$TTF)${}_{2}$$M$Hg(SCN)${}_{4}$ ($M=\text{K}$, Rb, Tl and NH${}_{4}$) and to resolve the difference between band picture and charge fluctuation of $\ensuremath{\alpha}$-(BEDT$\ensuremath{-}$TTF)${}_{2}$$M$Hg(SCN)${}_{4}$, we utilized ${}^{13}$C-NMR to examine $\ensuremath{\alpha}$-(BEDT$\ensuremath{-}$TTF)${}_{2}$RbHg(SCN)${}_{4}$ under the conditions with a large hyperfine coupling constant at each site. The temperature dependence of site susceptibility showed the development of spin disproportionation as observed in $\ensuremath{\alpha}$-(BEDT$\ensuremath{-}$TTF)${}_{2}$I${}_{3}$. We found that the linewidth of the A site only increased as temperature decreased from 200 to 100 K, a change associated with the development of lattice modulation. These findings indicate that density-wave modulation occurs during charge disproportionation instability.

The possibility of controlling traffic dynamics by applying high-frequency time modulation of traffic flow parameters is studied. It is shown that the region of the car density where the uniform (free) flow is unstable changes in the presence of time modulation compared with the unmodulated case. This region shrinks when the speed-up of cars does not exceed some critical value and expands in the opposite case. The flux of the time-modulated flow is an increasing function of the amplitude of the modulation for traffic flows whose density is larger than 1/h where h is the safety distance in the nonmodulated case, while it is a decreasing function in the opposite case. In other words, the safety distance time modulation facilitates car propagation in the case when the mean distance between cars in the congestive traffic is less than h and hinders it when the neighboring cars in the flow are well separated. A link between a microscopic description and the macroscopic fundamental diagram is established.

To investigate the superconducting (SC) state near a charge instability, we performed ^{13}C NMR experiments on the molecular superconductor beta"-(BEDT-TTF)_{4}[(H_{3}O)Ga(C_{2}O_{4})_{3}]C_{6}H_{5}NO_{2}, which exhibits a charge anomaly at 100 K. The Knight shift which we measured in the SC state down to 1.5 K demonstrates that Cooper pairs are in spin-singlet state. Measurements of the nuclear spin-lattice relaxation time reveal strong electron-electron correlations in the normal state. The resistivity increase observed below 10 K indicates that the enhanced fluctuation has an electric origin. We discuss the possibility of charge-fluctuation-induced superconductivity., 5 pages, 4 figures

In the temperature-pressure phase diagram of the organic superconductor (TMTSF)${}_{2}$PF${}_{6}$ (TMTSF: tetramethyltetraselenafulvalene), the superconducting phase and the spin-density-wave (SDW) phase are adjacent to each other. This salt exhibits non-Fermi-liquid (NFL) behavior and superconductivity under pressure. Its superconductive property does not exist at higher pressures where Fermi-liquid (FL) behavior is exhibited. In order to investigate the origin of NFL behavior, systematic $^{13}\mathrm{C}$-NMR measurement of this salt has been assessed under pressure in a wide temperature range. At low temperatures, $({T}_{1}T){}^{\ensuremath{-}1}$ increases, and this increase is suppressed by the increasing pressure. These results suggest that applying pressure alters the electron system from the NFL to the FL state, and that antiferromagnetic fluctuations contribute to the origin of NFL behavior. The connection between the emergence of FL behavior and the disappearance of superconductivity suggests that the SDW fluctuation relates to the mechanism of the superconductivity in (TMTSF)${}_{2}$PF${}_{6}$.

${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-(BEDT$\ensuremath{-}$TTF)${}_{3}$Cl${}_{2}$$\ifmmode\cdot\else\textperiodcentered\fi{}$2H${}_{2}$O [BEDT$\ensuremath{-}$TTF: $\underline{\mathrm{b}}$is-($\underline{\mathrm{e}}$thylene$\underline{\mathrm{d}}$i$\underline{\mathrm{t}}$hio)$\underline{\mathrm{t}}$etra$\underline{\mathrm{t}}$hia$\underline{\mathrm{f}}$ulvalene] is superconductive under pressures, whereas the salt exhibits metal-insulator (MI) transition under ambient pressure. The insulator phase in the salt was examined using the charge density wave (CDW) phase that was obtained from band calculation. The charge-ordered (CO) state was recently proposed as the insulator phase of the salt, and the mechanism of superconductivity intermediated by charge fluctuation was suggested. We accessed ${}^{13}$C-NMR on ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-(BEDT$\ensuremath{-}$TTF)${}_{3}$Cl${}_{2}$$\ifmmode\cdot\else\textperiodcentered\fi{}$2H${}_{2}$O at ambient pressure and under pressure up to 1.6 GPa. At ambient pressure, the NMR spectrum changed at approximately 100 K. Three isolated peaks appeared at low temperatures, suggesting that the CO state exists below 100 K, and spin-gap behavior was observed. By analyzing the chemical shift, the charges on the three sites were estimated as $\ensuremath{\sim}$+0.4$e$, $\ensuremath{\sim}$+0.6$e$, and $\ensuremath{\sim}$+1.0$e$. The ratio of peak intensity and unsymmetrical peak position suggest the CO state with some symmetry breaking. When pressure is applied, the splitting of the NMR peaks in the CO state is reduced. The salt finally exhibits superconductivity at 1.6 GPa, spin-gap behavior observed at ${({T}_{1}T)}^{\ensuremath{-}1}$ below 1.3 GPa suddenly disappears, whereas the NMR spectrum predicts that charge disproportionation coexists with superconductivity. The suppression of the spin-singlet formation observed in ${({T}_{1}T)}^{\ensuremath{-}1}$ at 1.6 GPa suggests the metallic state with the charge disproportionation and the CO instability with some symmetry breaking.

$\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu(NCS)${}_{2}$ [BEDT-TTF: bis-(ethylenedithio)-tetrathiafulvalene] behaves as a semiconductor at high temperatures, whereas it behaves as a Fermi liquid just above the superconducting transition temperature. To reveal the cause of this behavior, we experimented on $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu(NCS)${}_{2}$, in which one side of the central C$=$C in the BEDT-TTF molecules is substituted with $^{13}\mathrm{C}$ nuclei. We perfomed $^{13}\mathrm{C}$-nuclear magnetic resonance (NMR) spectroscopy on this salt and measured the temperature dependence of its spectral linewidths and its spin-spin relaxation time $T$${}_{2}$. We found anomalies in its linewidths and $T$${}_{2}$, which we connected to the ethylene motion within the salt. Compared with the $^{13}\mathrm{C}$-NMR measurements of $\ensuremath{\kappa}$-(BEDT-TTF-$d$8)${}_{2}$Cu(NCS)${}_{2}$, we obtained the experimental evidence of the connection between the ethylene motion and the conduction electrons. Considering this connection, we examined the semiconductive behavior of $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu(NCS)${}_{2}$ at high temperatures. The contribution of ethylene motion to the electronic state is thought to be a common feature of BEDT-TTF salts.

An organic salt, $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{4}{\text{Hg}}_{2.89}{\text{Br}}_{8}$ exhibits superconductivity at 4.3 K under ambient pressure suggesting non-Fermi-liquid (NFL) behavior just above ${T}_{c}$. Whereas most organic superconductors are controlled by the bandwidth in the half-filled electron system, this salt realizes a carrier doping away from the half-filled electron system as well as high-${T}_{c}$ cuprates. In order to investigate the origin of NFL behavior, we assessed $^{13}\text{C}$-NMR measurements in this salt and observed the antiferromagnetic fluctuation as same as in an organic antiferromagnet $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}\text{Cu}[\text{N}{(\text{CN})}_{2}]\text{Cl}$ with the gap structure. Application of pressure suppresses ${({T}_{1}T)}^{\ensuremath{-}1}$ and shifts its maximum to lower temperatures with ${({T}_{1}T)}^{\ensuremath{-}1}$ becoming constant above 2 GPa. These results suggest that applying pressure alters the electron system from NFL to FL state and that antiferromagnetic fluctuations contribute to the origin of NFL behavior.

A π–d hybrid electronic system, (DMe-DCNQI)2Cu, where the π orbital of the organic molecule, DMe-DCNQI, is strongly hybridized with the dxy orbital of Cu, has been studied by 15 N and 13 C NMR at three sites. The analysis of Knight shift, K, and local spin susceptibilities in the π and d orbitals was carried out separately. The π and d spin susceptibilities were found to be quite different in magnitude and temperature dependence. Moreover, the Knight shift was separated into those of two constituent bands; a one-dimensional π band and a three-dimensional π–d band. The relative weight of the band susceptibilities is strongly temperature dependent.

Among quasi-two-dimensional organic conductors, ${(\text{BEDT-TTF})}_{2}X$, what form the two column structure of $\ensuremath{\alpha}$ or $\ensuremath{\theta}$ is thought to show a charge-ordering insulating state. The ${\ensuremath{\alpha}}^{\ensuremath{'}}$ modification is the other candidate for a charge-ordering state. To determine the existence of a charge-ordering state and electron magnetism in the ${\ensuremath{\alpha}}^{\ensuremath{'}}$ phase, which has a symmetry that differs from that of the $\ensuremath{\alpha}$ and $\ensuremath{\theta}$ phases, we utilized $^{13}\text{C}\text{-NMR}$ to examine ${\ensuremath{\alpha}}^{\ensuremath{'}}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\text{IBr}}_{2}$ in which one side of the central carbon on the BEDT-TTF molecule is substituted with $^{13}\text{C}$ nuclei. We observed changes in its spectrum at 200 K. The angular dependence of the NMR shift at 15 K indicated that the charge-ordering pattern is intracolumn disproportionation and the ratio of charge disproportionation on the spin-poor site and spin-rich sites is almost 1:0. The angle dependence of NMR spectrum at 60 K suggests that the hyperfine coupling tensor in the paramagnetic charge-ordering state is determined not only by the charge density of on-site molecules but also by the contribution of off-site molecules. The change in hyperfine coupling tensor must be taken into account in NMR studies of the paramagnetic CO state.

In order to investigate the nature of the insulator phase of $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{C}\mathrm{N})}_{3}$ [where BEDT-TTF represents bis(ethylenedithio)terathiofulvalene] and why this salt is a superconductor under pressure but not under ambient pressure, we examined the $^{13}\mathrm{C}$ NMR spectra and spin lattice relaxation rate of $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{C}\mathrm{N})}_{3}$ under pressure. The spin susceptibility evaluated from the Knight shift decreased with increase in pressure, and line broadening was suppressed above a critical pressure. The temperature dependence of ${({T}_{1}T)}^{\ensuremath{-}1}$ for $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{C}\mathrm{N})}_{3}$ above a critical pressure was that for $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$, where $X$ was $\mathrm{Cu}[\mathrm{N}{(\mathrm{C}\mathrm{N})}_{2}]\mathrm{Br}$ or $\mathrm{Cu}{(\mathrm{N}\mathrm{C}\mathrm{S})}_{2}$. These results suggest that the electronic structure of $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{C}\mathrm{N})}_{3}$ under pressure is similar to that of other $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ salts. The results support our model that electron inhomogeneity and hopping conduction, which are common features of semiconductivity in $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ at high temperatures, are responsible for the insulator phase in $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{C}\mathrm{N})}_{3}$. The electron inhomogeneity suppresses the semiconductor-metal transformation and superconductivity observed in other $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ salts.

We present the temperature-dependent infrared and Raman spectra of ${\ensuremath{\beta}}^{\ensuremath{''}}\text{\ensuremath{-}}{(\mathrm{ET})}_{3}{X}_{2}$ ($X=\mathrm{H}\mathrm{S}{\mathrm{O}}_{4}$ and $\mathrm{Cl}{\mathrm{O}}_{4}$; $\mathrm{ET}=\mathrm{bis}$-ethylenedithio-tetrathiafulvalene) compounds which undergo a metal-insulator transition. The infrared-active ${v}_{27}$ mode discontinuously split into two bands at the metal-insulator transition temperature of $127\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in the $X=\mathrm{H}\mathrm{S}{\mathrm{O}}_{4}$ salt, whereas, the corresponding mode continuously changed across the metal-insulator transition temperature of $\ensuremath{\sim}170\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in the $X=\mathrm{Cl}{\mathrm{O}}_{4}$ salt. In both compounds, the charge-sensitive ${v}_{27}$ mode split into two in the insulating phase. This drastic spectral change indicates that the metal-insulator transition originated in the charge ordering. Employing the frequencies of the split ${v}_{27}$ bands, the site charges are estimated to be $+{0.3}_{4}$ and $+{0.8}_{1}$ for $X=\mathrm{H}\mathrm{S}{\mathrm{O}}_{4}$ and $+{0.3}_{6}$ and $+{0.8}_{1}$ for $X=\mathrm{Cl}{\mathrm{O}}_{4}$. We also estimated the site charges using the Raman-active ${v}_{2}$ mode and obtained consistent results. Examining the selection rule of the ${v}_{3}$ mode, we reached the conclusion that the unit cell with space group $P1$ has a pseudoinversion center in the charge-ordered phase. Based on the symmetry, we propose a charge-ordering pattern for the $X=\mathrm{H}\mathrm{S}{\mathrm{O}}_{4}$ and $X=\mathrm{Cl}{\mathrm{O}}_{4}$ salts, which is quite different from that of the $X=\mathrm{Re}{\mathrm{O}}_{4}$ salt reported previously. We qualitatively discuss the differences in the charge-ordering pattern considering the anisotropic intersite Coulomb interaction.

A $^{13}\mathrm{C}$-NMR study on nondeuterated and partially deuterated $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{C}\mathrm{N})}_{2}]\mathrm{Br}$ is reported, where BEDT-TTF is bis(ethylenedithio)tetra-thiafulvalene. By using a BEDT-TTF molecule with $^{13}\mathrm{C}$ as one of its central carbons, we could estimate the density of states from the Knight shift and the spin-lattice relaxation rate. Although the reduced mass effect predicted from the specific-heat measurement was not observed in the $^{13}\mathrm{C}$-NMR spectrum, a metal-to-antiferromagnetic phase transition was observed with a phase separation at around $18\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ on the half-deuterated $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{C}\mathrm{N})}_{2}]\mathrm{Br}$ under a high magnetic field. No such transition occurred in the half-deuterated salt under a zero or low field. These results point to a first-order field-induced metal-insulator transition. These findings can explain the complex phenomena observed near the phase boundary under a high magnetic field.

$\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ salts exhibit a wide range of properties from superconductivity to magnetic ordering. The phase diagram of this system has been understood as the competition between anti-ferromagnetic insulating behavior and superconductivity. The $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ system has been well explained using a parameter, U/W, as well as the high ${T}_{c}$ cuprates. $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{CN})}_{3}$, however, behaved as an insulator without magnetic ordering. This salt cannot be described by the phase diagram described by the competition between superconductivity and magnetism. It is interesting to explore the nature of this insulating phase with an eye toward understanding the universal phase diagram of the $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ system. Magnetic frustration due to the triangular spin lattice has recently been reported for $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{Cu}}_{2}{(\mathrm{CN})}_{3}$ from $^{1}\mathrm{H}$-nuclear magnetic resonance (NMR) study. To investigate the insulating properties of this salt, we characterized it using $^{13}\mathrm{C}\text{\ensuremath{-}}\mathrm{NMR}$. In contrast to previous $^{1}\mathrm{H}\text{\ensuremath{-}}\mathrm{NMR}$ studies, at low temperatures, we observed line broadenings that were proportional to the hyperfine coupling constants, which suggested inhomogeous electron localization. We also observed antiferromagnetic fluctuations which, as is the case with other salts, intensified with decreasing temperature. To understand the electronic properties of $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}X$ system, in addition to the U/W, the electron localization effect from the relatively narrow bandwidth is important.

This paper deals with the formulation that can analyze vibration noise problems practically in the flexible multibody systems. Many kinds of formulations have been proposed on the flexible multibody systems so far. They are categorized into several groups according to their purposes and coordinate systems. The floating frame of reference formulation is at present the most popular method for general purpose simulations among them. The formulation uses Cartesian coordinates for the position of a body, Euler angles or Euler parameters for the orientations, and modal coordinates for the elastic degrees of freedom. The equations of motion with these different kinds of coordinates are complicated because of coupling between rigid body motion and elastic vibration. On the other hand, the linear theory of elasto-dynamics appears to be simple and could be practical for some limited uses. But it neglects the effect of the elastic deformation on the rigid body motion. In many cases, the effect is significant and essential. In this paper, we propose a new formulation with rigid body modes and a local observer frame (LOF) for large amplitude rigid body motion, and with elastic modes for small amplitude elastic vibration. The LOF is updated properly to compensate the gap between rigid body motion and the LOF motion. The new formulation makes the coupling terms as simple as possible without any loss of the effect of the elastic deformation on the rigid body motion and gives the uniform description in each modal coordinate.

We assessed the infrared-absorption spectra and $^{13}\text{C}$-NMR measurements in a layered organic salt, ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)(TCNQ), which exhibits antiferromagnetic transitions at 20 and 3 K. The former originates from the spin in the bis-(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) layers, while the latter originates from the localized spin in the tetracyanoquinodimethane (TCNQ) layers. Using infrared-absorption spectroscopy, we estimated the degree of charge transfer, $\ensuremath{\rho}$, between BEDT-TTF and TCNQ as 0.5. Using $^{13}\text{C}$-NMR spectroscopy, we observed an exchange field at the BEDT-TTF site, which is produced by the localized spins of TCNQ dimers. Using the obtained value of $\ensuremath{\rho}$ and the molecular arrangement of ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)(TCNQ), which is similar to that of the highest ${T}_{c}$ organic superconductor, ${\ensuremath{\beta}}^{\ensuremath{'}}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\text{ICl}}_{2}$, we concluded that the absence of the pressure-induced superconductivity in ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)(TCNQ) results from the presence of this exchange field. The exchange interaction, $J$, and the exchange field, ${H}_{ex}$, were estimated as $\ensuremath{-}12\text{ }\text{K}$ and $\ensuremath{-}19\text{ }\text{T}/{\ensuremath{\mu}}_{B}$ on the TCNQ dimer unit, respectively. These findings suggest that superconductivity may arise in ${\ensuremath{\beta}}^{\ensuremath{'}}$-(BEDT-TTF)(TCNQ) by the application of an external field of 19 T under high pressure.

A follow-the-leader model of traffic flow on a closed loop is considered in the framework of the extended optimal velocity (OV) model where the driver reacts to both the following and the preceding car. Periodic wave train solutions that describe the formation of traffic congestion patterns are found analytically. Their velocity and amplitude are determined from a perturbation approach based on collective coordinates with the discrete modified Korteweg-de Vries equation as the zero order equation. This contains the standard OV model as a special case. The analytical results are in excellent agreement with numerical solutions.

The phase transition found in the electrical resistivity of α'-(BEDT-TTF)2IBr2 was investigated by observing the charge-sensitive phonon modes of BEDT-TTF. The low-temperature phase was elucidated to be a charge-ordered state with large amplitude. The pattern of charge-order was a horizontal or diagonal stripe, which requires the breaking of inversion symmetry. The breaking of symmetry was confirmed by observing the asymmetric stretching mode of IBr2-. The symmetry breaking occurs primarily at -200 K rather continuously. It was proposed in the high-temperature phase that the nearly localized charges are dynamically fluctuating individually or collectively with a fluctuation rate much slower than 55 cm-1.