Although both granular gases (GG) and molecular gases (MG) are characterized by random motions of their constituents, phenomena not possible for MG, such as clustering and Maxwell’s demon are reported in GG. The origin of these intriguing phenomena is the dissipative collisions in GG which are coupled to the local density of the GG in a spatially extended or compartmentalized system. Systems with two or more types of grains are especially interesting because the asymmetry in the dissipative collisions between different types of grains can lead to oscillations and even more interesting dynamics. In this article, flux models with different granular temperatures for different types of grains are studied to understand and explore these phenomena.

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This article gives an overview of recent theoretical and experimental findings concerning the hydrodynamic interaction between liquid-embedded particles in various confined geometries. A simple unifying description emerges, which accounts for the various findings based on the effect of confinement on conserved fields of the embedding liquid. It shows, in particular, that the hydrodynamic interaction under confinement remains long-ranged, decaying algebraically with inter-particle distance, except for the case of confinement in a rigid linear channel.

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Liquid crystal colloids are composite materials made up of colloidal particles and liquid crystalline host fluids. After introducing various specific properties of liquid crystal collloids that are absent in conventional colloidal systems, we review our studies, based mainly on computer simulations using Landau–de Gennes theory, to elicudate those properties of liquid crystal colloids. We first present our attempts to investigate the orientational profiles and defect structures of a nematic liquid crystal around one colloidal particle. We successfully reproduce two configurations observed experimentally when strong homeotropic anchoring is imposed at the particle surface; one is a configuration with a hedgehog defect, and in the other, the particle is encircled by a ring defect referred to as a Saturn ring. Next we focus on the interaction between particles mediated by the elastic distortions of the host nematic liquid crystal. We calculate the interaction between particles carrying a hedgehog, and that between particles connected by a birefringent region called a bubble-gum. The properties of those interactions obtained numerically have been recently verified experimentally in a quantitative manner. We also review some of the important and attractive features of liquid crystal colloids not mentioned in the main part of the present paper.

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We review our recent studies on glassy dynamics and glass transition of polymer thin films using neutron and X-ray reflectivity and inelastic neutron techniques. In the last decade extensive studies have been performed on polymer thin films to reveal very interesting but unusual properties such as reduction in the glass transition temperature T_g with film thickness and negative thermal expansivity for thin films below about 25 nm, and often some contradictory experimental results have been reported. It is believed that a key to solve the controversial situation is to disclose heterogeneous structure or multi-layer structure in polymer thin films. In the review, therefore, we summarize our recent experimental results by neutron and X-ray reflectivity and inelastic neutron scattering, focusing on the dynamic heterogeneity in polymer thin films.

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Soft matter such as liquid crystals, polymer solutions and colloidal dispersions are complex fluids that exhibit viscoelasticity. Their macroscopic mechanical properties have been studied intensively in the field of rheology. Recently, the structures and dynamics of soft matter at micro- and nanoscale have attracted considerable attention from researchers. The study of microrheology, which deals with the mechanical properties of soft matter at the mesoscopic scale, has made remarkable progress owing to theoretical and technical developments. In this review, we present the basic methods of microrheology and their practical applications to soft matter. We also stress the importance of these methods for understanding fundamental physical problems in nonequilibrium systems at the mesoscopic scale.

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Inspite of the fluid nature and low elastic modulus, membranes play a crucial role in maintaining the structural integrity of the cell. Recent experiments have challenged the passive nature of the membrane as proposed by the classical fluid mosaic model. Experiments indicate that biomembranes of eukaryotic cells may be laterally organized into small nanoscopic domains, called rafts, which are rich in sphingomyelin and cholesterol. It is largely believed that this in-plane organization is essential for a variety of physiological functions such as signaling, recruitment of specific proteins and endocytosis. However, elucidation of the fundamental issues including the mechanisms leading to the formation of lipid rafts, their stability, and their size remain difficult. This has reiterated the importance of understanding the equilibrium phase behavior and the kinetics of fluid multicomponent lipid membranes before attempts are made to find the effects of more complex mechanisms that may be involved in the formation and stability of lipid rafts. Current increase in interest in the domain formation in multicomponent membranes also stems from the experiments demonstrating fluid–fluid coexistence in mixtures of lipids and cholesterol and the success of several computational models in predicting their behavior. Here we review time dependent Ginzburg Landau model, dynamical triangulation Monte Carlo, and dissipative particle dynamics which are some of the methods that are commonly employed.

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Recent developments in lipid membrane models for simulations are reviewed. To reduce computational costs, various coarse-grained molecular models have been proposed. Among them, implicit solvent (solvent-free) molecular models are relatively more coarse-grained and efficient for simulating large bilayer membranes. On a μm scale, the molecular details are typically negligible and the membrane can be described as a continuous curved surface. The theoretical models for fluid and elastic membranes with mesh or meshless discretizations are presented. As examples of applications, the dynamics of vesicles in flows, vesicle formation, and membrane fusion are presented.

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Various types of supertough polymer gels capable of high recoverable deformability and/or with high shear/compressive moduli are investigated by small-angle neutron scattering (SANS) and mechanical measurements. These gels have unique structures, such as sliding cross-links (slide-ring gels), plane cross-links by clay platelets (nanocomposite gels; NC gels), and tetrahedral networks (tetra-PEG gels). One of the common features of these gels is that frozen inhomogeneities inherent to polymer gels are negligible. This fact, observed by SANS measurements, indicates that cross-links are introduced very effectively. Hence, the mechanical properties of these gels are expected to be well predicted by the theories of rubber elasticity. In this review, we discuss the relationship between the structure and mechanical properties of supertough polymer gels. Furthermore, we address the necessary conditions for high-performance polymer gels in the analogy of rubber.

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It is well known that polymeric systems exhibit a wide variety of self-organized structures such as droplet-dispersed and bicontinuous structures in polymer blends, spheres, cylinders, lamellae, and gyroid ones in diblock copolymer systems. Various numerical methods have been developed to investigate the static and dynamic properties of self-organized structures that appear in polymeric systems. Among others, it has been recognized that the self-consistent field theory and density functional theory have a prominent potential to predict the phase behaviors of polymeric systems. In the present review, the self-consistent field theory and recently developed linear mean field theory as an extension of the density functional theory are introduced.

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Spatially uniform electric fields have been used to induce instabilities in liquids and polymers, and to orient and deform ordered phases of block-copolymers. Here we discuss the demixing phase transition occurring in liquid mixtures when they are subject to spatially nonuniform fields. Above the critical value of potential, a phase-separation transition occurs, and two coexisting phases appear separated by a sharp interface. Analytical and numerical composition profiles are given, and the interface location as a function of charge or voltage is found. The possible influence of demixing on the stability of suspensions and on inter-colloid interaction is discussed.

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Block copolymer phases are a fertile ground in which to investigate both equilibrium and nonequilibrium properties of mesophases (phases that exhibit partial broken symmetries, intermediate between a completely disordered fluid and a perfectly order crystal). We focus here on two particular phases: a lamellar phase (of smectic symmetry, solid like in one direction and fluid in the two other directions), and a columnar phase (a hexagonal solid in two dimensions, and fluid in the third dimension). Starting from a mesoscopic model of the copolymer, we present the amplitude equations of motion for tilt and twist grain boundaries, and the resulting equations of motion for slightly distorted boundaries. We also examine the assumptions underlying the separation of scales in the derivation of the amplitude equations, and analyze corrections to the equations due to the coupling to the O(1) variation of the order parameter in the vicinity of the boundaries. These corrections can lead to defect pinning. The effect of pinning on defect motion depends on whether the bifurcation originating the mesophase is super or sub critical.

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We report pure noise-induced pattern formations in a homeotropically aligned nematic liquid crystal. Williams domains and stripe patterns are induced by colored and white noises, respectively, and the Fredericks transition is also found, which has no dependence on correlation time of the external noise. Furthermore, threshold behavior in the presence of a regular (sinusoidal) field superposed with the noise was investigated to understand the intrinsic role of the noise on the mechanisms driving noise-induced patterns and transitions.

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According to Fermi’s golden rule, the radiative decay rate of excitons in a thin film becomes higher with increasing film thickness because of the increment of the interaction volume between excitons and photons. However, for a thick film, the decay rate is inversely proportional to the film thickness, because the excitons behave as polaritons and the decay time is proportional to the time of flight. This contradiction reflects a breakdown of Fermi’s golden rule in the exciton–photon interaction. We have revealed the breakdown condition by a rigorous calculation method that connects the two radiative decay schemes.

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The results of synchrotron X-ray diffraction by the coupled dimer compound SrCu₂(BO₃)₂ subjected to a pulsed high magnetic field are reported. We find the lattice constant, a, contracts with increasing magnetic field. This change in the lattice constant scales with the magnetization change. We argue that the nearest neighbor exchange interaction between Cu²⁺ spins is an antiferromagnetic one through an oxygen and its strength depends on the bond angle Cu²⁺–O²⁻–Cu²⁺. The bond length between the Cu ions in a triplet becomes shorter to make the bond angle smaller and to diminish the antiferromagnetic exchange interaction. We propose this mechanism as a main source of the lattice contraction.

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Electrical resistivities, Hall coefficients, and thermoelectric powers have been measured for polycrystalline samples of LaFe_1−yCo_yAsO_1−xF_x (x=0.11) with various values of y. The results show that there exists a clear distinction of these transport behaviors between the superconducting and nonsuperconducting metallic regions of y divided by the boundary value y_c∼0.05. We have found that the behaviors in both regions are very similar to those of high-T_c Cu oxides in the corresponding phases. If they reflect, as in the case of Cu oxides, the effects of strong magnetic fluctuations, the energy scale of the fluctuations is considered to be smaller than that of the high-T_c Cu oxides by a factor of ∼1⁄2. Arguments on the electronic nature and superconducting symmetry are presented on the basis of the observed small rate of the T_c suppression caused by Co doping.

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Magnetic properties of the spin-1/2 kagome-like compound volborthite are studied using a high-quality polycrystalline sample. It is evidenced from magnetization and specific heat measurements that the spins on the kagome lattice still fluctuate at low temperature, down to T=60 mK that corresponds to 1/1500 of the nearest-neighbor antiferromagnetic interaction, exhibiting neither a conventional long-range order nor a spin gap. In contrast, ⁵¹V NMR experiments revealed a sharp peak at 1 K in relaxation rate, which indicates that a certain exotic order occurs. Surprisingly, we have observed three “steps” in magnetization as a function of magnetic field, suggesting that at least four liquid-like or other quantum states exist under magnetic fields.

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The parent compound of the Fe oxypnictide superconductor, LaFeAsO, has been studied by pulsed neutron powder inelastic scattering measurement. The inelastic scattering intensity along the Q-axis at T=140 K exhibits a prominent asymmetric peak ascribed to the (π,π,l) magnetic rod, suggesting the two-dimensionality of the spin density wave above the magnetic transition temperature. It persists even in the tetragonal phase up to room temperature, which is well above the magnetic transition temperature, corresponding to two antiferromagnetic sublattices or domains with a strong effective antiferromagnetic interaction J₂ between next-nearest-neighbour Fe magnetic moments in a single Fe square lattice.

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We have performed a variational Monte Carlo simulation on a two-dimensional t–t′–t″–U Hubbard model with a Bi-2212-type band to examine the stability of a 4×4 checkerboard state, which has been observed recently by scanning tunneling microscopy (STM) in Bi-2212 and Na-CCOC. The condensation energies of inhomogeneous magnetic and charge-ordered states at 1/8 hole doping are calculated. We found that the coexistent state of bond-centered four-period diagonal and vertical spin-checkerboard structures characterized by a multi-Q set is stabilized and composed of 4×4 period checkerboarded spin modulation. This state can be understood as an incommensurate spin density wave enhanced by Fermi surface nesting, which appears in the precursory peaks of spin susceptibility at ∼(π,π⁄2), (π⁄2,π), and (π⁄2,π⁄2).

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The weak itinerant ferromagnet UIr is studied by magnetization and magnetostriction. Critical behavior, which surprisingly extends up to several Tesla, is observed at the Curie temperature T_C\\simeq45 K and is analyzed using Arrott and Maxwell relations. Critical exponents are found that do not match with any of the well-known universality classes. The low-temperature magnetization M_s\\simeq0.5 μ_B below 3 T rises towards higher fields and converges asymptotically around 50 T with the magnetization at T_C. From the magnetostriction and magnetization data, we extract the uniaxial pressure dependences of T_C, using a new method presented here, and of M_s. These results may serve as a basis for understanding spin fluctuations in anisotropic itinerant ferromagnets.

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The normal-state spin dynamics of the recently discovered iron-pnictide superconductors is discussed by calculating the spin structure factor S(q,ω) in an itinerant five-band model within random phase approximation (RPA). Owing to the characteristic Fermi surface structure of iron pnictide, a column-like response is found at (π,0) in extended Brillouin zone in the undoped case, which is consistent with the recent neutron scattering experiment. This indicates that the localized spin model is not necessary to explain the spin dynamics of this system. We also study NMR 1⁄T₁T in the same footing calculation and show that the itinerant model can capture the magnetic property of iron-pnictide superconductors.

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We derive the thermal conductivities of one-dimensional harmonic and anharmonic lattices with self-consistent heat baths from the single-mode relaxation time (SMRT) approximation. For harmonic lattice, we obtain the same result as previous works. However, our approach is heuristic and reveals phonon picture explicitly within the heat transport process. The results for harmonic and anharmonic lattices are compared with numerical calculations from Green–Kubo formula. The consistency between derivation and simulation strongly supports that effective (renormalized) phonons are energy carriers in anharmonic lattices although there exist some other excitations such as solitons and breathers.

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We systematically calculate the total reaction cross sections of oxygen isotopes, ^15–24O, on a ¹²C target at high energies using the Glauber theory. The oxygen isotopes are described with Slater determinants generated from a phenomenological mean-field potential. The agreement between theoretical and experimental results is generally good, but a sharp increase of the reaction cross sections from ²¹O to ²³O remains unresolved. To examine the sensitivity of the diffraction pattern of elastic scattering to the nuclear surface, we study the differential elastic-scattering cross sections of proton-^20,21,23O at the incident energy of 300 MeV by calculating the full Glauber amplitude.

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This paper investigates the evolution of granular temperatures for the oscillation of a bidisperse granular mixture in a vertically vibrated two-compartment container. The oscillation describes a periodic switch of light-particle cluster, followed by heavy-particle cluster, from one compartment to the other. We divide one half of a period of granular oscillation into L1-, L2-, and H-stages, depending on which type of particle is jumping over the barrier between the two compartments. The particle tracking velocimetry technique is used to measure particle velocities, from which the granular temperatures of each type of particles in each compartment are obtained. This study demonstrates that a temperature driven mechanism alone cannot explain the phenomenon of granular oscillation. In the H-stage (L2-stage), the difference in temperatures for heavy particles (light particles) between the two compartments is able to drive the particle flow; however, temperature mechanism is not valid in the L1-stage. The granular oscillation is then analyzed by a flux model, which confirms the temperature mechanism in the H- and L2-stages, and suggests that concentration difference could be an alternative factor to drive the light-particle flow in the L1-stage. In addition, a molecular dynamics simulation is also performed to study the evolution of granular oscillation.

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We analyze the existence of small amplitude solitons on the background of a continuous wave in negative index materials by establishing an interesting connection between the modified nonlinear Schrödinger equation and Korteweg–de Vries equation. It is shown that the dynamical equation for modulated short pulses admits a novel small amplitude soliton solution analytically and which propagate in the negative index medium. We also examine the influence of nonlinear dispersion terms over the modulation instability windows arising in a modified nonlinear Schrödinger equation pertaining to negative index materials using well established semi-analytics called linear stability analysis. Gain spectrum investigation has been carried out for both anomalous and normal dispersion regimes.

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Statistical and stochastic properties of the stacking sequences of SiC nanowires are investigated to reveal the rule by which the successively growing layers stack. We show that the stacking sequences exhibit multiscaling. We also observe marked stacking property changes when a cubic segment becomes as long as 5–8 Si–C double layers: long segments tend to follow a power law, while short segments have an exponential distribution.

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An anomalously soft bulk solid with a parabolic acoustic-phonon dispersion relation of ω=ak² type is extensively investigated qualitatively and quantitatively from a microscopic point of view. The peculiar dispersion relation leads us to a characteristic spectral dimension, a mechanical instability and a thermal instability, and the sound wave obeys a special wave equation in the long-wavelength limit. When the instabilities are suppressed by a cutoff frequency or a suitable unharmonicity, acoustic phonons exhibit many peculiar features. A significant localization character is numerically observed in the low-frequency region of acoustic phonons when we introduce disorder into the solid. It is clarified that the localization is qualitatively stronger in force-constant-disordered systems than in mass-disordered systems.

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We present the anomalies at ∼200 K in electrical resistivity, transmittance and reflectance in the far-infrared region, and the magnetic susceptibility of α′-(BEDT-TTF)₂IBr₂ [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene]. This phase transition is investigated by infrared, Raman, and far-infrared spectroscopies. Through the spectroscopic investigation, we found that the positive charges on BEDT-TTF molecules are strongly localized owing to a strong Coulomb interaction in both low-temperature (LT) and high-temperature (HT) phases. We show the spectroscopic data that suggest the charge order in the LT phase and the charge disorder in the HT phase. The phase transition at ∼200 K in α′-(BEDT-TTF)₂IBr₂ is the charge order–disorder phase transition not accompanied by structural changes. On the basis of the localized picture, we qualitatively interpreted the experimental results above and below the phase transition. The effect of hydrostatic pressure was investigated by electrical resistivity measurement and Raman spectroscopy. The charge-ordered state is successively suppressed by applying hydrostatic pressures of up to 1.2 GPa. The resistivity and Raman spectrum qualitatively change above 1.4 GPa. We speculate that the phase transition changes the character from a charge order–disorder to a metal–insulator.

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Orbital hybridization and Fermi surface of Ca_2−xSr_xRuO₄ in metallic phases (0.2≤x≤2) are studied by using first-principles electronic-structure calculations with spin–orbit coupling (SOC). The SOC effect appears almost negligible in the electronic structure near the Fermi energy in Sr₂RuO₄, while it turns out to be significant in Ca_2−xSr_xRuO₄ (x=0.5 and 0.2) because of coupling with symmetry lowering due to rotation and tilt of RuO₆ octahedron. Calculated Fermi-surface topology for Ca_2−xSr_xRuO₄ (x=0.5 and 0.2) is reasonably consistent with recent angle-resolved photo-emission spectroscopy measurements.

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The itinerant quasi-ferromagnetic metal MnSi has been studied by detailed thermal expansion measurements under pressures and magnetic fields. A sudden decrease of the volume at the critical pressure P_c∼1.6 GPa has been observed and is in good agreement with the pressure variation of the volume fraction of the spiral magnetic ordering. This confirms that the magnetic order disappears by a first order phase transition. The energy change estimated by the volume discontinuity on crossing P_c is of similar order as the Zeeman energy of the transition from the spiral ground state to a polarized paramagnetic one under magnetic field. In contrast to the strong pressure dependence of the transition temperature, the characteristic fields are weakly pressure dependent, indicating that the strength of the ferromagnetic and the Dzyaloshinskii–Moriya interactions do not change drastically around P_c. The evaluated results of the thermal expansion coefficient and the magnetostriction are analyzed thermodynamically. The Sommerfeld coefficient of the linear temperature term of the specific heat is enhanced just below P_c. The magnetic field-temperature phase diagrams in the ordered and paramagnetic phases are also compared. Comparison is made with other heavy fermion compounds with first order phase transition at 0 K.

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From our study of the evolution of charge ordering in Bi_0.5Ca_0.5−xSr_xMnO₃ (x=0–0.5) with chemical pressure, we found the detailed nature of two distinct charge ordering schemes, associated with the structural change from Pnma- to Imma-type symmetry at x=0.2–0.25. Charge ordering for x=0–0.2 (Pnma) is consistent with the checkerboard-type pattern, commonly observed in half-doped manganites. On the other hand, a large tolerance factor for x=0.25–0.5 (Imma) stabilizes a double-stripe charge ordering scheme. These findings indicate the bicritical nature of two competing charge ordered states and provide further insight towards understanding the dominant charge ordering mechanism in half-doped manganites.

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We study theoretically the superconductivity in NpPd₅Al₂, the first neptunium-based heavy-fermion superconductor discovered recently. We calculate the dynamical susceptibility and estimate the occurrence of superconductivity in NpPd₅Al₂, in terms of the fluctuation-exchange approximation (FLEX) on a Hubbard model with tight-binding dispersion consistent with the band calculation. We show that the feature of band structures in NpPd₅Al₂ enhances nearly antiferromagnetic spin fluctuations, giving rise to a superconducting state with the d_x²−y² symmetry.

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We calculated the electronic and lattice properties of 10H-BN and 10H-AlN which are sp³-bonded compounds. The 10H polytype has various 18 structures. Possible symmetries and hexagonalities [H (%)] in them are P6₃mc and P3m1, and 20, 40, 60, and 80%, respectively. Four structures in the 10H polytype are considered in this study. Their stacking sequences (ABC notation) are ABCABCBACB (P6₃mc, H=20%), ABCABCABAB (P3m1, H=40%), ABCBCACBCB (P6₃mc, H=60%), and ABCBCBCBCB (P3m1, H=80%). Their lattice properties were optimized automatically by the first-principles molecular dynamics (FPMD) method. The calculated total energies of 10H-BN are in the order of ABCABCBACB (20%) < ABCABCABAB (40%) < ABCBCACBCB (60%) < ABCBCBCBCB (80%). The calculated total energies of 10H-AlN are in the order of ABCBCBCBCB (80%) < ABCBCACBCB (60%) < ABCABCABAB (40%) < ABCABCBACB (20%). Values in parentheses are hexagonalities (%). The most stable structures in the calculated 10H-BN and 10H-AlN are ABCABCBACB and ABCBCBCBCB, respectively. The total energy of the BN polytype increases with increasing hexagonality. In contrast, the total energy of the AlN polytype decreases with increasing hexagonality. This trend is consistent with the our previous results of 2H–6H-BN(AlN) polytypes. We calculated the electronic band structures, the band gap values, the valence band maximum (VBM), and conduction band minimum (CBM) of the above four structures in 10H-BN and 10H-AlN, respectively. Their electronic band structures are non-metallic and band gaps are indirect.

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We investigate the two-photon absorption (TPA) spectrum in Mott insulators on the basis of dynamical cluster approximation. The nonlocal correlation is found to be important in enhancing the dimensionality dependence of the TPA spectrum. The dependence of the TPA spectrum on Coulomb interaction is modified compared with that of the dynamical mean field theory, which is also caused by a nonlocal correlation through a one-particle spectrum. We compare several degrees of nonlocality by adjusting the cluster momentum. The iterated perturbation theory is adopted as an impurity solver, and then a comparison with the noncrossing approximation is presented. It is confirmed that the predominant optical process in Mott insulators is different from that of conventional semiconductors, and small Mott insulating gaps are favorable for obtaining a large TPA spectrum.

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We present the results of high-resolution measurements of the thermal expansion and magnetostriction of the cubic filled skutterudite compound PrFe₄P₁₂. The temperature dependence of the thermal expansion ΔL(T)⁄L for the three main symmetry directions are nearly identical below T_A, in accordance with a recently proposed scalar order parameter for the A-phase. In the field-angle dependence of the transverse thermal expansion ΔL(θ)⁄L along the [001] direction (θ is the angle between the [100] direction and the orientation of a magnetic field within the (001) plane), we find clear twofold oscillation. On the basis of mean-field analyses, we show that the observed twofold oscillation can be interpreted as the the crystal field effect for the cubic T_h symmetry. Our results suggest that the crystal field scheme consists of a Γ₁ ground state and a Γ₄⁽¹⁾ first-excited state, in both the non-ordered and A-phases.

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We investigate the characteristics of itinerant to localized transition of f electrons in heavy fermion systems in terms of the generalized Ginzburg–Landau (GL) theory based on the Kondo lattice model, in which the static thermal fluctuations of Kondo bosons are taken into account by the mean mode–mode coupling approximation. For a finite gradient term in the GL expansion corresponding with heavy fermions, we obtain a first-order phase transition from the mean-field heavy-fermion state at low temperatures (T) and low magnetic fields (H) to the asymptotically free local moment regime at high T and high H. The asymptotic freedom of the local moments at high T is represented by a gradual logarithmic function of lnT similarly to the impurity Kondo problem, whereas that at high H by a relatively sharp function of H⁻¹ different from lnH, giving rise to a metamagnetism similar to the experimental results of heavy fermion materials.

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Single crystals of Ru₇B₃ were grown by the Czochralski puling method in a tetra-arc furnace. The compound crystallizes in a Th₇Fe₃-type structure (hexagonal, space group: P6₃mc), which has no inversion symmetry along the c-axis. Measurements in magnetic fields indicate type-II superconductivity with upper critical fields of H_c2(0)\\simeq17.2 kOe for H||[001] and 15.8 kOe for H||[100], respectively. The coherence length ξ(0)_GL, penetration depth λ(0)_GL, and Ginzburg–Landau (GL) parameter κ(0) obtained from these values are 144 Å, 3110 Å, and 21.6 for H||[100], and 138 Å, 3520 Å, and 25.5 for H||[001], respectively. Specific heat measurements reveal that Ru₇B₃ is a weak-coupling superconductor with an isotropic superconducting gap.

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The small-angle neutron scattering measurement of Pd nanoparticles was performed to investigate their intraparticle magnetic structures. The magnetic scattering from the magnetization of the samples was observed using the polarized neutron. The nuclear scattering indicated that the Pd nanoparticles can be regarded as spherical particles, and the magnetic scattering is explained based on the shell model that the particle is composed of magnetic core and shell. The magnetic moment of the core was larger than that of the shell. These results suggest that the spontaneous magnetization of the Pd nanoparticles mainly exists in the core region.

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We grew high-quality single crystals of NpAl₄, together with UAl₄, by the Al-flux method and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization and de Haas–van Alphen (dHvA) effect. NpAl₄ is an antiferromagnet with the Néel temperature T_N=49 K. The corresponding magnetic moment is most likely directed along the [010] direction in the orthorhombic crystal structure. The large magnetic entropy at T_N and the Curie–Weiss behavior suggest the localized nature of 5f-electrons with the 5f⁴ configuration. The detected dHvA frequencies in NpAl₄ are small, indicating that the small magnetic Brillouin zone is formed in the antiferromagnetic state. On the other hand, the large Fermi surfaces are observed in a paramagnet UAl₄. The detected cyclotron mass is relatively large, ranging from 3.4 to 23m₀, which is consistent with the electronic specific heat coefficient γ=89 mJ/(K²·mol).

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We theoretically investigate how the photoexcited states change across the phase boundary between the charge density wave (CDW) and the spin density wave (SDW) states in the one-dimensional (1D) and the two-dimensional (2D) Pariser–Parr–Pople models in the strong interaction case. In the 1D case, the CDW (singlet spin pair) droplet states dominate light absorption spectrum in the SDW (CDW) ground state region near the phase boundary. These photoexcited states exhibit crossover behavior across the phase boundary, that is, the density of the CDW region gradually increases across the phase boundary from the SDW to the CDW ground state region. On the contrary, in the 2D case, the bound holon–doublon (singlet spin) pair state dominates the light absorption spectrum, and the quantum fluctuations of the CDW or the singlet spin pair domain are negligible in the dominant photoexcited state even near the phase boundary. As a result, the transition occurs in the dominant photoexcited state at the ground state phase boundary.

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The Griffiths inequalities for Ising spin glasses are proved on the Nishimori line with various bond randomnesses including Gaussian and ±J bond randomnesses. The proof for Ising systems with Gaussian bond randomness has already been carried out by Morita et al., which uses not only the gauge theory but also the properties of the Gaussian distribution, so that it cannot be directly applied to the systems with other bond randomnesses. The present proof essentially uses only the gauge theory, so that it does not depend on the detailed properties of the probability distribution of random interactions. Thus, the results obtained from the inequalities for Ising systems with Gaussian bond randomness also hold for those with various bond randomnesses, particularly ±J bond randomness.

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In the system we consider, a pair of large hard spheres, whose surface separation is fixed at a prescribed value, is immersed in a binary mixture comprising small and medium hard spheres. The density profiles of the medium and small spheres near the large spheres are calculated using the three-dimensional integral equation theory. When the surface separation equals the medium-sphere diameter, a medium sphere is held between the large spheres in contact with both of their surfaces. This is represented by an extremely sharp, high peak in the reduced density profile of medium spheres. It is found that the profile can be reproduced by the Kirkwood superposition approximation using the reduced density profile of medium spheres around a single large sphere, which is calculated using the radial-symmetric integral equation theory. The small spheres are excluded by the medium sphere held as described above, and the thermal pressure due to the small spheres acting on each large-sphere surface becomes highly asymmetrical. This asymmetry induces a strongly attractive force between the large spheres. The exclusion of the small spheres by the medium sphere is exhibited in the reduced density profile of the small spheres.

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We use resonant X-ray emission spectroscopy and model calculations to quantify the ligand: heme-Fe energy structure of aqueous myoglobins. For reduced (Fe²⁺) and oxidized (Fe³⁺) states, the removal or addition of an electron primarily involves charge changes on the ligand-site, and not the Fe-site. The results indicate a finite positive/negative charge-transfer energy Δ between the heme-Fe 3d and ligand valence electronic states for Fe²⁺/Fe³⁺. Thus, the energy difference between the ligand and Fe 3d states (+Δ or −Δ) determines the charge properties of myoglobins. The study provides a reliable method for characterizing ligand-metal binding of biological systems in solution.

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