# Showing papers in "Journal of the Physical Society of Japan in 1982"

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TL;DR: In this article, the low temperature mobility of a two-dimensional system at a GaAs/Al x Ga 1-x As heterojunction was calculated in a twodimensional system.

Abstract: The low temperature mobility is calculated in a two-dimensional system at a GaAs/Al x Ga 1- x As heterojunction. Scattering mechanisms are assumed to be the Coulomb scattering from ionized donors in the Al x Ga 1- x As layer, interface roughness, and scattering caused by alloy disorder present in the Al x Ga 1- x As layer. The calculated mobility for the Coulomb scattering explains recent experimental results. The interface roughness and the alloy scattering can play a role at high electron concentrations (∼10 12 cm -2 ).

288 citations

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TL;DR: In this paper, the authors measured the resistivity and the Hall coefficient of 2 H metallic transition-metal dichalcogenides between 4.2 K and 300 K in order to investigate the carrier scattering mechanisms in a CDW system.

Abstract: Detailed measurements of the resistivity and the Hall coefficient have been made on high-quality single crystals of 2 H metallic transition-metal dichalcogenides between 4.2 K and 300 K, in order to investigate the carrier scattering mechanisms in a CDW system. The resistivity of 2 H -NbS 2 , which has no CDW transition, shows normal behavior. On the other hand, in 2 H -TaSe 2 which has the highest CDW transition temperature ( T o =122 K) of 2 H family, several anomalous features are observed. The temperature dependence of the resistivity in 2 H -TaSe 2 is ∼ T 5 ( T T o ). The results were analyzed by including a “new” scattering mechanism due to phase fluctuations of the CDW (electron-phason scattering, phase disorder scattering). The analysis suggests that McMillan's phonon entropy model is more appropriate in 2 H -TaSe 2 than the conventional model.

261 citations

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TL;DR: In this article, a standardized formulation for the lineshape problem was introduced, and the effect of lattice vibrations on the exciton absorption was used in a Monte Carlo calculation of the density of exciton states and the absorption spectra in the regime of weak scattering.

Abstract: A standardized formulation is introduced for the lineshape problem–the effect of lattice vibrations on the exciton absorption, and used in a Monte-Carlo calculation of the density of exciton states and the absorption spectra in the regime of weak scattering. For the direct edge, we obtain the asymmetric lineshape with a strongly decaying low-energy side while the high-energy side can be approximated by a life-time broadened Lorentzian. The linewidth is found to depend on temperature as T 2/3 , T 1 and T 3/2 for one-, two-, and three-dimensional lattices in agreement with renormalized perturbation theory in one and two dimensions. The discrepancy of the perturbational result ( T 2 ) in three dimensions is ascribed to the density of states which is most sensitive to disorder in this case. The shift of the absorption peak is found to be linear in T for low T , the origin of its sublinear behaviour for higher T is clarified.

209 citations

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TL;DR: In this paper, the subband structure of a two-dimensional electron system at a GaAs/Al x Ga 1-x As heterojunction interface is calculated, where many-body exchange and correlation effects are taken into account.

Abstract: The subband structure of a two-dimensional electron system at a GaAs/Al x Ga 1- x As heterojunction interface is calculated. Many-body exchange and correlation effects are taken into account in the local density-functional approximation. They are shown to be unimportant but not negligibly small. Spectra of light scatterings are also calculated. Results are in reasonable agreement with existing experiments.

203 citations

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TL;DR: In this paper, the effects of localization on two-dimensional superconductors have been investigated by taking into account quantum corrections to the theory of dirty superconductions in the order of ( e F τ 0 ) -1 where e F and τ 0 are the Fermi energy and the relaxation time of an electron, respectively.

Abstract: Effects of localization on two-dimensional superconductors have been investigated by taking into account quantum corrections to the theory of dirty superconductors in the order of ( e F τ 0 ) -1 where e F and τ 0 are the Fermi energy and the relaxation time of an electron, respectively. The mean field superconducting transition temperature is seen to be reduced by localization. This is because the Coulomb repulsive interaction is enhanced and the density of states of electrons is depressed in dirty systems. Recent experiments by Kobayashi et al. on granular films of tin are discussed in this context.

195 citations

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TL;DR: In this paper, it is shown that the coupled KdV equation introduced by the present authors is a special case of the four-reduced KP hierarchy which is included in the general theory of τ functions.

Abstract: It is shown that the coupled KdV equation introduced by the present authors is a special case of the four-reduced KP hierarchy which is included in the general theory of τ functions. From the fact it is also shown that the soliton solutions can be derived from those of the KP equation. Moreover, the existence of infinitely many conserved quantities are proved by means of the linear scheme giving the coupled KdV equation.

173 citations

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TL;DR: In this paper, the inverse scattering method was used to find the multiple-pole solutions of the Modified Korteweg-de Vries equation, i.e., the solutions which correspond to multiple-poles of the reflection coefficient, which describe a weak bound state of solitons and antisolitons.

Abstract: New types of solutions of completely integrable nonlinear evolution equations are found using the inverse scattering method. For the Modified Korteweg-de Vries equation the multiple-pole solutions, i.e., the solutions which correspond to multiple-pole of the reflection coefficient are investigated. Double-pole soltuion and triple-pole solution are obtained explicitly. It is shown that those solutions describe a weak-bound state of solitons and antisolitons.

157 citations

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TL;DR: In this article, the magnetic structure and weak ferromagnetic magnetism of Mn 3 Sn were studied by polarized neutron diffraction at room temperature and it was shown that the spin structure has a triangular configuration of inverse geometry in the c-plane and the triangle rotates opposite to the rotation of the c -plane field component.

Abstract: The magnetic structure and weak ferromagnetism of Mn 3 Sn were studied by polarized neutron diffraction at room temperature. The flipping ratio was measured for a number of Bragg reflections by rotating the crystal about the scattering vector under a magnetic field of 8 kOe applied perpendicular to the scattering vector. It was found that the spin structure has a triangular configuration of inverse geometry in the c -plane and the triangle rotates opposite to the rotation of the c -plane field component. From the analysis of the anisotropy energy it was shown that the triangle of inverse geometry is stabilized by the Dzyaloshinski-Moriya interaction and the weak ferromagnetic moment appears from the mechanism that each spin in the inverse triangle tilts slightly toward its easy axis. It was also shown that the weak ferromagnetic moment rotates just opposite to the rotation of the triangle.

150 citations

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TL;DR: A quasi one-dimensional Hubbard model embodying features of (TMTSF) 2 PF 6 etc was studied in this article, where the SDW gap equation derived by a variational method was solved.

Abstract: A quasi one-dimensional Hubbard model embodying features of (TMTSF) 2 PF 6 etc. was studied. The SDW gap equation derived by a variational method is solved. The gap parameter is derived at OK and at finite temperatures as a function of the transverse electron transfer energy t '. The SDW transition proves to be of the second order. The upper and lower bands separated by the SDW gap start to overlap due to finite value of t ' when the gap becomes smaller than the magnitude of modulation of band extrema. The temperature dividing the SDW phase into semiconducting and semimetallic phases is also obtained. Physical properties such as state density, magnetoresistivity, conductivity, susceptibility etc. are briefly described. Experimental observations agree qualitatively well with the above results, if we take t '∼300 k B and assume appropriate pressure dependence of t '.

144 citations

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TL;DR: In this article, the authors analyzed the low-energy tail of the exciton absorption spectra calculated numerically on the standard model of exciton-phonon interaction and established the empirical Urbach rule in its exponential decay.

Abstract: We analyze the low-energy tail of the exciton absorption spectra calculated numerically on the standard model of exciton-phonon interaction. The empirical Urbach rule is established in its exponential decay for several orders of magnitude with a decay constant proportional to inverse temperature T -1 in two and three dimesnions and to T -2/3 in one dimension. A posteriori, the exponential tail is unambiguously ascribed to the “momentarily localized” excitons by considering the behaviour of the average oscillator strength per state. We introduce the steepness index s which relates the steepness coefficient σ and the exciton-phonon coupling constant g through σ= s / g . Our calculated values of 1.24 for square and 1.50 for simple cubic lattices enable us to correlate experimental observations on Urbach behaviour and self-trapping consistently.

144 citations

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TL;DR: In this article, the energy band structure of black phosphorus was calculated by using self-consistent pseudopotential method and the resulting band structure has the direct minimum gap at the point Z in the Brillouin zone in agreement with the result of the tight-binding approach.

Abstract: The energy band structure of black phosphorus is calculated by using self-consistent pseudopotential method. The resulting band structure has the direct minimum gap at the point Z in the Brillouin zone in agreement with the result of the tight-binding approach. Effective electron and hole masses and the level shift of the band edge by pressure are calculated from the bands obtained. The pressure dependence of the energy gap is in good agreement with experiment, but the anisotropy of the effective masses contradicts that of the electrical conductivity measured for the single crystal. The nature of the optical absorption edge is discussed in terms of the calculated band structure.

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TL;DR: In this article, the effects of intra-state correlation on the variable range hopping were investigated in the absence and presence of a magnetic field, and the intrastate correlation was found to have a linear dependence on the magnetic field in lower magnetic fields.

Abstract: Effects of intra-state correlation on the variable range hopping are investigated in the absence and presence of a magnetic field. In the absence of a magnetic field, Mott's expression for the resistivity, ρ∝exp [ T 0 / T ] 1/4 , still holds in its temperature dependence. However, the prefactor T 0 now depends on two types of localization lengths brought about by the intra-state correlation. Magnetoresistance is found to be positive due to the intra-state correlation. It shows a linear dependence on a magnetic field in lower magnetic fields and saturates above a certain magnetic field.

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TL;DR: In this article, a new type of differential-difference equation is proposed as an extension of Volterra equation, and one-and two-soliton solutions to this equation are obtained by using Hirota's method.

Abstract: A new type of differential-difference equation is proposed as an extension of Volterra equation. One- and 2-soliton solutions to this equation is obtained by using Hirota's method. N-soliton solution is also conjectured.

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TL;DR: In this paper, the Galerkin method was used to solve the eigenvalue problem of the critical Rayleigh number for a horizontal magnetic fluid layer confined between two ferromagnetic boundaries and heated from below in the presence of a vertical magnetic field.

Abstract: The linear instability is investigated for a horizontal magnetic fluid layer confined between two ferromagnetic boundaries and heated from below in the presence of a vertical magnetic field Galerkin method is used for solving the disturbance equations The resultant eigenvalue problem is solved numerically The critical Rayleigh number varies with the magnetic number, N , as R a c =1067(1- N / N 0 ), where N 0 is a function of M 3 , a measure of the nonlinear magnetization of fluid, and decreases from 1417 to 1067 as M 3 increases from 0 to ∞ The linear relation between R a c and N is proved analytically for very large values of M 3 It is concluded that the magnetization of the boundaries and the non-linearity of fluid magnetization both reduces R a c , and that the effects of magnetic force and buoyancy compensate each other

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Osaka University

^{1}TL;DR: In this paper, the magnetization and magnetoresistance of itinerant electron helical magnet MnSi was studied down to 0.45 K and the existence of two new phases were suggested.

Abstract: Magnetization and magnetoresistance of itinerant electron helical magnet MnSi has been studied down to 0.45 K. A large negative magnetoresistance is observed especially around Neel temperature T N in accord with the theoretical expectation. Below 1 K, however, a positive magnetoresistance is found and it is attributed to the normal magnetoresistance due to impurity scattering. Anomalous peaks in the magnetization and magnetoresistance are observed just below T N between about 1.0 and 2.2 kOe and the existence of two new phases are suggested.

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Kyoto University

^{1}TL;DR: An integrable spin model on the one-dimensional lattice is obtained from the differential-difference nonlinear Schrodinger equation by introducing the concept of gauge equivalence as mentioned in this paper.

Abstract: An integrable spin model on the one-dimensional lattice is obtained from the differential-difference nonlinear Schrodinger equation by introducing the concept of gauge equivalence. The Hamiltonian for this spin model is expressed as \begin{aligned} H{=}-2\sum_{n}{\log}(1+\textbf{\itshape S}_{n}\cdot \textbf{\itshape S}_{n+1}) \end{aligned} where the spins S n are classical three-dimensional unit vectors.

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TL;DR: The magneto-volume effect of the weak itinerant ferromagnet MnSi has been studied by measuring both the thermal expansion over a wide range of temperature and the forced volume megnetostriction at different temperatures as discussed by the authors.

Abstract: The magneto-volume effect of the weak itinerant ferromagnet MnSi has been studied by measuring both the thermal expansion over a wide range of temperature and the forced volume megnetostriction at different temperatures. The forced magnetostriction at 4.2 K as well as the magnetic thermal expansion at 10 kOe, Δω m ( H , T ) can well be described by a formula Δω m ( H , T )= K C Δ[ M ST ( H , T ) 2 ] with K C =1.5×10 -10 (mol/emu) 2 where Δ[ M ST ( H , T ) 2 ] is the change of square of magnetization by polarization of the d band. The spontaneous magnetostriction at 0 K, Δω m (0,0) is related to the spontaneous magnetization M (0,0) by \(\Delta\omega_{\text{m}}(0,0){\doteqdot}(2/5)KC\ M(0,0)^{2}\) with the same K C . Furthermore magneto-v olume effect becomes positive above T c . All of these features agree satisfactorily with those predicted by Moriya and Usami based on spin fluctuation theory.

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TL;DR: In this paper, the average oscillator strength per state (AOSPS) is defined as the ratio of the exciton absorption lineshape and the density of exciton states at a given energy.

Abstract: We introduce the average oscillator strength per state (AOSPS) as the ratio of the exciton absorption lineshape and the density of exciton states at a given energy. The numerical investigation of the AOSPS spectra and their dependence on temperature and dimensionality shows contrasting behaviour on the two sides of the absorption peak. Unambiguously we can ascribe the high-energy side to indirect transitions and the low-energy tails to momentarily localized states with giant oscillator strength. The calculated spectra of the participation ratio lend further support to this viewpoint.

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TL;DR: In this paper, the crystal structure of antiferroelectric PbZrO 3 has been studied at room temperature by adopting X-ray and neutron profile analysis methods, and a considerable refinement of the structure has been made on a previous model which has generally been accepted in these 20 years.

Abstract: Crystal structure of antiferroelectric PbZrO 3 has been studied at room temperature by adopting X-ray and neutron profile analysis methods. A considerable refinement of the structure has been made on a previous model which has generally been accepted in these 20 years. In contrast to the old model which has a large spontaneous polarization, present model has no polarization at all, and the interatomic distances are reasonable magnitude. Several contradictions having been noticed between the dielectric properties and the structural nature are now completely resolved.

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TL;DR: In this article, the phase transition in {N(CH 3 ) 4 } 2 XBr 4 (X: Zn, Co, Cu) was stuided by dielectric measurements.

Abstract: The phase transitions in {N(CH 3 ) 4 } 2 XBr 4 (X: Zn, Co, Cu) were stuided by dielectric measurements. A phase transition which accompanied with a break on the dielectric constant vs temperature curve was found at 13.5°C and 13.8°C for {N(CH 3 ) 4 } 2 ZnBr 4 and {N(CH 3 ) 4 } 2 CoBr 4 , respectively. In {N(CH 3 ) 4 } 2 CuBr 4 three phase transitions were found at -1°C, -31°C, and -36°C on cooling. In the temperature range between -31°C and -36°C the crystal shows ferroelectricity along the pseudo-hexagonal c -direction. The spontaneous polarization is about 7×10 -8 C cm -2 .

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TL;DR: In this article, it was shown that the modulation wave vector exhibits remarkable thermal hysteresis over a wide temperature range including the incommensurate-commensurate transition point in the mixed crystal system.

Abstract: The modulation wavevector \(k_{z}{=}(\frac{1}{3}{-}\delta)c^{*}\) exhibits remarkable thermal hysteresis over a wide temperature range including the incommensurate-commensurate transition point in the mixed crystal system (Rb 1- x K x ) 2 ZnCl 4 with x =0, 0.005, 0.02, 0.28, 0.92, 0.997 and 1. This hysteresis seems to correspond to the thermal hysteresis observed in the dielectric constant and to support the proposal by Hamano et al . that the pinning of the modulation wave by defects causes the hysteresis. In the Rb rich case ( x ≦0.02), the parameter δ has a tendency to be fixed to the value realized at the normal-incommensurate transition point. In the K rich case ( x =0.997), it decreases monotonically with decreasing temperature, with a plateau in a middle range of the incommensurate phase. In the middle range of x , δ is pinned to a constant value down to low temperature.

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TL;DR: In this paper, the electronic structure of disordered Ni-Pd alloys is investigated by means of the KKR method which is combined with the CPA and the local spin-density approximation.

Abstract: The electronic structure of disordered Ni–Pd alloys is investigated by means of the KKR method which is combined with the CPA and the local-spin-density approximation. Good overall agreements with the measurements are obtained for the magnetic moment distribution and for the hyperfine field at Ni nucleus. The origins of the large magnetic moment at Ni site (∼1.2 µ B ) and the positive hyperfine field on the Ni nucleus, both in Pd-rich region, are discussed in the light of the present calculation which can reproduce them quantitatively.

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TL;DR: Using an effective Hamiltonian to describe the dynamics of the center coordinates of the cyclotron motion, the structure of the tail states of the Landau subbands is discussed in this paper.

Abstract: Using an effective Hamiltonian to describe the dynamics of the center coordinates of the cyclotron motion, the structure of the tail states of the Landau subbands is discussed Eigenvalue problem is explicitly solved in the case of a single Gaussian-type potential The eigenfunctions do not depend on the range of the potential while the eigenvalues do The contribution of the tail states to the dynamical conductivity is shown to be proportional to D ( E F ) 2 ω 2 In ω in the low frequency limit with D ( E F ) the density of states at the Fermi energy E F

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TL;DR: In this article, it was shown that the Schrodinger equation and the Heisenberg ferromagnet equation can be transformed into the same bilinear form with the Pohlmeyer-Lund-Regge-Getmanov equation.

Abstract: Transformations of soliton equations into the bilinear forms involving four dependent variables are discussed. It is found that both nonlinear Schrodinger equation and classical Heisenberg ferromagnet equation are transformed into the same bilinear from, while the equation \begin{aligned} \phi_{xt}{=}\phi(1-|\phi_{t}|^{2})^{1/2} \end{aligned} shares the same bilinear form with the Pohlmeyer-Lund-Regge-Getmanov equation. Transformations of the complex sine-Gordon equation and the Landau-Lifshitz equation into the bilinear forms are also described.

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TL;DR: In this paper, the frequency of transverse (TO) and longitudinal (LO) modes of the infrared active species have been obtained from the observed reflectivities, and the TO-LO splitting supplies a criterion for the ionic character.

Abstract: The infrared transmission and reflection spectra of Co II Co III 2 O 4 , CoAl 2 O 4 , ZnFe 2 O 4 and MnFe 2 O 4 and the single crystal Raman spectra of Co II Co III 2 O 4 and CoAl 2 O 4 have been measured. The frequencies of the transverse (TO) and longitudinal (LO) modes of the infrared active species have been obtained from the observed reflectivities. The TO-LO splitting supplies a criterion for the ionic character. The lattice dynamical analysis of the optically active vibrations has been made for Co II Co III 2 O 4 , CoAl 2 O 4 and ZnFe 2 O 4 , in which the rigid ion model for the long-range Coulomb potential and the central force field for the short-range potential have been used. The obtained short-range potential constants have been discussed, in relation to the bond character.

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TL;DR: In this article, the optical properties of alkaline-earth chalcogenides, including the frequency of transverse and longitudinal optical phonons and related dispersion parameters are analyzed.

Abstract: Single crystals of alkaline-earth chalcogenides, CaS, CaSe, SrS, SrSe, BaS and BaSe, have been prepared by the floating-zone method using a Xe-arc image furnace. Details of the crystal growth technique are described. As the first report of our studies on the optical properties of these IIa-VIb compounds, the infrared reflection spectra due to the optical phonons are presented. From a dispersion analysis of the spectra, the frequencies of transverse and longitudinal optical phonons and related dispersion parameters are determined. Discussions are made on the effective charges and the chemical trend of these binary compounds.

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TL;DR: In this paper, the magnetic structure of a weak ferromagnetic Mn 3 Sn has been studied by polarized neutron diffraction at room temperature, and large flipping ratios were observed for the 100 and 110 reflections under application of a magnetic field in the c -plane perpendicular to the scattering vector.

Abstract: The magnetic structure of a weak ferromagnetic Mn 3 Sn has been studied by polarized neutron diffraction at room temperature. Large flipping ratios were observed for the 100 and 110 reflections under application of a magnetic field in the c -plane perpendicular to the scattering vector. The spin structure deduced from the h 0 l and h h l reflections has a triangular configuration but the spin plane is not determined. For applied field parallel to [010] the spin-A is parallel to [010], but for applied field parallel to [\bar110] the spin-B is antiparallel to [\bar110]. The magnetic form factor of the Mn atom agrees with the calculated Mn 2+ form factor and the magnetic moment is 1.78 µ B /Mn.

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TL;DR: In this paper, the crystallographic parameters of compounds MnAs 1-x P x (0≦ x ≦ 0.275) were determined as a function of temperature between about 100 and 600 K. Simple analysis of the experimental results revealed the way in which the spin value of Mn atoms and the exchange interaction between them depend on the crystal voluem (or lattice parameter).

Abstract: The crystallographic parameters of compounds MnAs 1- x P x (0≦ x ≦0.275) are determined as a function of temperature between about 100 and 600 K. It is found that these crystals except for MnAs take a MnP type structure in low temperature side and transform to a NiAs type at critical temperatures. These structural transitions are of second kind and accompanied with very large dilation (∼10%) of crystal volume. In order to see the relationship between the structural and magnetic properties, the temperature variation of magnetic susceptibilities of the compounds is also measured. Simple analysis of the experimental results, based on the Curie-Weiss law, reveals the way in which the spin value of Mn atoms and the exchange interaction between them depend on the crystal voluem (or lattice parameter).

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TL;DR: In this paper, the dielectric constant along the ferroelectric b -axis and spontaneous polarization have been measured for CsH 2(1- x ) D 2 x PO 4 (x = 0∼0.98) over wide temperature ranges.

Abstract: The dielectric constant along the ferroelectric b -axis and the spontaneous polarization have been measured for CsH 2(1- x ) D 2 x PO 4 ( x =0∼0.98) over wide temperature ranges. The temperature dependences of the dielectric constant in the paraelectric phase are well described on the basis of the quasi-one-dimensional Ising model except in the vicinity of the Curie temperatures, 0K\({\leq}T{-}T_{\text{c}}{\lesssim}20\) K, for all the specimens with different amounts of x . The saturated value of the spontaneous polarization increases with increasing x . The observed results are discussed in terms of the quasi-one-dimensional model.

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Kyoto University

^{1}TL;DR: In this paper, it was shown that two inverse scattering formalisms by Ablowitz, Kaup, Newell and Segur are connected through a gauge tranformation and a transformation of the space and time coordinates depending on a dependent variable.

Abstract: It is shown that two inverse scattering formalisms by Ablowitz, Kaup, Newell and Segur and by Wadati, Konno and Ichikawa are connected through a gauge tranformation and a transformation of the space and time coordinates depending on a dependent variable. One-soliton solutions of equations associated with the W-K-I scheme are also examined.