Showing papers in "Journal of the Physical Society of Japan in 1977"
TL;DR: In this article, a nonlinear partial difference equation which reduces to the sine-Gordon equation in the continuum limit is obtained and solved by the method of dependent variable transformation, and the Backlund transformation and the inverse scattering form for this equation are presented.
Abstract: A nonlinear partial difference equation which reduces to the sine-Gordon equation in the continuum limit, is obtained and solved by the method of dependent variable transformation. N -soliton solutions, the Backlund transformation and the inverse scattering form for this equation are presented.
388 citations
TL;DR: In this article, a nonlinear partial difference equation which approximates the Korteweg-de Vries equation in the weakly nonlinear and continuum limit is obtained, and N-soliton solutions, the Backlund transformation and the inverse scattering transform are presented.
Abstract: A systematic method for isolating certain nonlinear partial difference equations that exhibit solitons is proposed. A nonlinear partial difference equation which approximates the Korteweg-de Vries equation in the weakly nonlinear and continuum limit, is obtained. N-soliton solutions, the Backlund transformation and the inverse scattering transform for this equation are presented.
373 citations
TL;DR: In this article, it was shown that if electrons of a plasma have two different temperatures, there exists an electron acoustic mode when the number of high-temperature electrons is smaller than that of low-temperat...
Abstract: It is shown that if electrons of a plasma have two different temperatures, there exists an electron acoustic mode. When the number of high-temperature electrons is smaller than that of low-temperat...
264 citations
TL;DR: In this article, the magnetic properties of a triangular Ising lattice with antiferromagnetic nearest neighbor interaction and ferromagnetic second neighbor interaction were investigated at finite-temperature.
Abstract: Molecular field approximation is applied to a triangular Ising lattice with antiferromagnetic nearest neighbor interaction J and ferromagnetic second neighbor interaction J ' to study the magnetic behavior at finite temperatures. In the range of 0> J '/ J >-0.8, with increasing temperature the system is found to have a second-order transition from a ferrimagnetic state to an antiferromagnetic state in which one of three sublattices is completely disordered. Another second-order transition occurs in the ferrimagnetic state. Magnetic structure factor, free energy, magnetic specific heat, differential magnetic susceptibility as well as sub-lattice magnetization are calculated numerically with parameter J '/ J . Critical magnetic field of first-order transition from antiferromagnetic state to ferrimagnetic state is also evaluated. Discussion is given in connection with magnetic ordering in CsCoCl 3 and CsCoBr 3 .
247 citations
TL;DR: In this paper, the broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p-type Si at zero temperature.
Abstract: The broadening of Landau levels and the transport quantities, such as the transverse and Hall conductivity and cyclotron resonance linewidth, are calculated in an inversion layer on the (100) surface of p -type Si at zero temperature. Main scattering mechanisms are assumed to be charged impurity scattering and surface roughness scattering. A new expression for the surface roughness scattering is obtained. The self-consistent Born approximation is employed for the effect of scattering, and the random phase approximation for the screening. Because of the singular density of states the screening depends on the position of the Fermi level and becomes weak when it lies at the tail region of each Landau level. Scattering potentials become strong and of slowly varying type in this case. Except such a special case, overall features agree with the results obtained for short-ranged scatterers.
188 citations
TL;DR: In this article, a Backlund transformation in bilinear forms is presented for a higher order Korteweg-de Vries equation, which is a natural extension of the Korte-de-Vries equation written in a bilinearly form.
Abstract: A Backlund transformation in bilinear forms is presented for a higher order Korteweg-de Vries equation, which is a natural extension of the Korteweg-de Vries equation written in a bilinear form. The Backlund transformation in ordinary forms and the inverse scattering scheme are given for this higher order equation. Also, the first eleven of the infinity of conservation quantities for this equation are derived from the Backlung transformation.
170 citations
TL;DR: It has been found that Rb 2 ZnCl 4 shows phase transitions at about -81 and 29°C, respectively, and is ferroelectric in a direction below -81°C as mentioned in this paper.
Abstract: It has been found that Rb 2 ZnCl 4 shows phase transitions at about -81 and 29°C, respectively and is ferroelectric in the a direction below -81°C.
146 citations
TL;DR: In this article, a general theory of transient light scattering was developed on the basis of the stochastic theory of intermediate state interaction, and the transient behaviors of various components of the second orde...
Abstract: A general theory of transient light scattering is developed on the basis of our stochastic theory of intermediate state interaction. The transient behaviors of various components of the second orde...
139 citations
TL;DR: In this article, the electronic band structure of the first-stage potassium-graphite intercalation compound C 8 K was calculated by a semi-empirical tight-binding scheme.
Abstract: The electronic band structure of the first-stage potassium-graphite intercalation compound C 8 K was calculated by a semi-empirical tight-binding scheme. The calculated Fermi surfaces can be classified into two distinct types. One is potassium-like and nearly isotropic; the other is carbon-like and of cylindrical shape. In addition, the cylindrical portions show nesting property, which is likely to induce charge-density-wave instability. The isotropic portions of the Fermi surfaces are responsible for the large reduction of anisotropy in conductivity of C 8 K relative to graphite. The calculated density of states has a peak around the Fermi level and is in good agreement with the observed density of states derived from the specific heat measurements.
133 citations
TL;DR: In this paper, the magnetic properties of hexagonal Fe 2 P single crystal are studied by the measurements of magnetization, susceptibility, thermal expansion and electrical resistivity along the principal crystallographic axes.
Abstract: The magnetic properties of hexagonal Fe 2 P single crystal are studied by the measurements of magnetization, susceptibility, thermal expansion and electrical resistivity along the principal crystallographic axes. It is found that the saturation magnetization per molecule and the Curie temperature are 2.94 µ B and 208.6 K, respectively, and the anisotropy constant K 1 is 2.32×10 7 erg/cm 3 at 4.2 K, which is considerably larger than the values in 3d-transition compounds. The thermal expansion and the electrical resistivity show discontinuous changes at the Curie temperature indicating that the ferromagnetic to paramagnetic transition of Fe 2 P is accompanied by the first-order transition due to magnetoelastic effects. The exchange striction obtained from the measurement of thermal expansion is discussed on the basis of the theory of Bean and Rodbell.
120 citations
TL;DR: In this paper, a domain-like structure of the I-CDW state is realized as the fundamental wave vector of the 1T-TaS 2 state approaches to the commensurate (3×1) wave vector, which is consistent with the recent X-ray photoemission experiment by Hughes and Pollak.
Abstract: The incommensurate (I) states of the triple charge density waves (CDW) in 1T-TaS 2 are studied in details by taking into account a sufficiently large number of harmonics. A domain-like structure of the I-CDW state is shown to be realized as the fundamental wave vector of the I state approaches to the commensurate (“3×1” superstructure) wave vector; the domain boundary is characterized generally by a change of the phase and amplitude of the CDW, and inside the domain an approximately commensurate CDW is stabilized. The nature of the commensurability energy and the coexistence of three CDW's are reflected in the pattern of the domain-like structure. The successive first-order transitions in 1T-TaS 2 are discussed in this connection. The presence of a domain-like structure, which our theory predicts for the nearly commensurate phase of 1T-TaS 2 , is consistent with the recent X-ray photoemission experiment by Hughes and Pollak.
TL;DR: In this article, a detailed theoretical analysis of non-Ohmic transport of electrons on the liquid 4 He surface is given, where the correct form of the electron-ripplon scattering as well as the electron 4 He gas scattering is taken into account.
Abstract: Detailed theoretical analysis of non-Ohmic transport of electrons on the liquid 4 He surface is given. The correct form of the electron-ripplon scattering as well as the electron- 4 He gas scattering is taken into account. A characteristic electric field at which electron mobility deviates from the Ohmic value is estimated as a function of temperature and the holding field on the basis of the electron effective temperature approximation.
TL;DR: In this article, the electron localization in the Anderson model of disordered two dimensional square lattices is investigated numerically in the case of large systems composed of 10 4 sites, where the Anderson transition at the band center and the localization near the mobility edge are recognized.
Abstract: The electron localization is investigated numerically in the Anderson model of disordered two dimensional square lattices. The spatial behaviors of wavefunctions are examined for large systems composed of 10 4 sites. Computations are carried out to see the Anderson transition at the band center and to see the localization near the mobility edge. Sharp transition at the band center is recognized and the electron localization is clearly visualized. The spatial decay rate of localized wavefunction is evaluated in the localized region and its dependence on energy or the degree of disorder is determined.
TL;DR: In this paper, the energy band structures of Gd-pnictides, GdX(X=N, P, As and Sb), known to show a transition from a semiconductor to a metal in the series from GdN to GdSb, are calculated using the APW method.
Abstract: Energy band structures of Gd-pnictides, GdX(X=N, P, As and Sb), known to show a transition from a semiconductor to a metal in the series from GdN to GdSb, are calculated using the APW method It is found that the energy bands depend sensitively on a choice of the one-electron potential Then, the calculation is carried out self-consistently The calculated bands account qualitatively well for the observed trend of the conducting properties through the pnictides The density of states agrees reasonably well with experimental results The Fermi surface of metallic pnictides is calculated both for paramagnetic and ferromagnetic states It consists of simple closed electron and hole surfaces Relativistic effects are investigated using first-order perturbation theory They do not affect seriously nonrelativistic bands
TL;DR: In this paper, the electrical resistivity of antiferromagnetic metals is discussed on the basis of the two band model and the general expression in terms of the dynamical susceptibility is obtained.
Abstract: The electrical resistivity of antiferromagnetic metals is discussed on the basis of the two band model. The general expression in terms of the dynamical susceptibility is obtained. The resistivity is studied by using the self-consistent renormalization theory of spin fluctuations. The resistivity at low temperatures is proportional to T 2 and its coefficient diverges as |α-1| -1/2 as one approaches the critical boundary of antiferromagnetism. It is pointed out that in the ordered phase the effect of the gap in the conduction band is important. Especially, this effect plays a crucial role in the temperature dependence of the contribution of the spin waves. It is proportional to T 5 and T 2 at the temperatures lower and higher, respectively, than the gap energy. At high temperatures the resistivity is significantly suppressed from that calculated by using RPA results for the spin fluctuations and can have a tendency towards saturation.
TL;DR: In this article, a formulation based upon the extended zone scheme is presented with the main interest in the valley splitting in an n -channel (100) inversion layer of Si.
Abstract: The theories based upon the multi-valley effective mass equation proposed by Twose are criticized and it is concluded that they can not explain the observed valley splittings. In order to treat valley splittings correctly, a formulation based upon the extended zone scheme is presented with the main interest in the valley splitting in an n -channel (100) inversion layer of Si.
TL;DR: In this article, the electronic structures of water and ice are investigated by means of XPS, UPS, and VUV absorption spectroscopy, and it is suggested that ice is essentially a kind of molecular crystal.
Abstract: Electronic structures of water and ice are investigated by means of XPS, UPS and VUV absorption spectroscopy. All the bands found in the XPS spectra of ice show a fairly good agreement with the electronic band structure theoretically calculated for cubic ice using molecular tight binding approximation. From the UPS spectra the vacuum level of ice is found at 10.5 eV above the top of the valence band, and a conduction band level of high density of states at 3.5 eV above the vacuum level. In VUV spectra D 2 O ice film shows a well separated absorption band at 8.75 eV, whose shape is almost independent of temperature, and it is suggested that ice is essentially a kind of molecular crystal. The absorption coefficients in the tail regions of the fundamental absorption bands of water and ice show nearly exponential dependence on the photon energy, and they seem to be well expressed as the tail of a Gaussian band.
TL;DR: In this paper, the properties of a mixture of two anisotropic antiferro-magnets with different easy axes have been analyzed both in mean field approximation and in the method of distribution function.
Abstract: Thermal and magnetic properties of a mixture of two anisotropic antiferro-magnets with different easy axes have been analyzed both in mean field approximation and in the method of distribution function. A new phase called OAF phase is found within a certain range of concentration. In OAF phase, the spin of each species of ion on a sublattice has each own axis of sublattice magnetization tilting oblique to the easy axes of the pure systems. As temperature increases, OAF phase makes a transition into the antiferromagnetic phase and then to the paramagnetic phase successively. It is expected that these transitions are detected by measurements of specific heats for a powder sample and of susceptibilities for a single crystal. It is also pointed out that magnetization processes show some characteristic features of OAF phase.
TL;DR: In this paper, the de Haas-van Alphen (dHvA) effect in LaB 6 single crystal has been studied in detail using the field modulation technique and the electron density calculated from the Fermi surface is 1.39×10 22 cm -3 which corresponds to just one electron per unit cell.
Abstract: The de Haas-van Alphen (dHvA) effect in LaB 6 single crystal has been studied in detail using the field modulation technique. Observed dHvA frequencies in the (010) and (1\bar10) planes range from the order of 10 6 to 10 8 gauss. The angular dependence of the dHvA frequencies and the disappearance of the oscillation in some angular regions indicate that the Fermi surface of LaB 6 consists of a multiply connected surface, large pieces of which are centered at the point X (or M) in the simple cubic Brillouin zone. The electron density calculated from the Fermi surface is 1.39×10 22 cm -3 which corresponds to just one electron per unit cell.
TL;DR: In this paper, an experimental study was carried out on the interaction of two vortex rings moving in air side by side along their parallel axes and the behavior of two rings was observed by a flow visualization method and the three-dimensional structure of the cross-linking of the two vortex filaments was studied.
Abstract: Experimental studies were carried out on the interaction of two vortex rings moving in air side by side along their parallel axes. The behavior of two rings was observed by a flow visualization method and the three-dimensional structure of the cross-linking of the two vortex filaments was studied. This phenomena were classified into three patterns, depending on the initial speeds of two rings. (1) At lower speed, two rings merge into one distorted ring. (2) At higher speed, it splits into two rings again after merging, (3) At still higher speed, they merge, split and merge again into one ring before they diffuse away. Theory of virtual momentum was examined in the case of this interaction of two vortex rings.
TL;DR: X-ray diffraction experiments of a single crystal of magnetite at 84 K were carried out to investigate the crystal symmetry below the transition temperature as discussed by the authors, and a new lattice deformation which makes crystal symmetry lower than rhom-bolaedral was clarified.
Abstract: X-ray diffraction experiments of a single crystal of magnetite at 84 K were carried out to investigate the crystal symmetry below the transition temperature. A new lattice deformation which makes the crystal symmetry lower than rhom-bolaedral was clarified. The extra reflections which appear in the low temperature phase were observed for the first time with X-ray diffraction. The extinction of (4, 4, \(\pm\frac{1}{2}\)) reflections, which was found by Iizumi and Shirane by means of neutron diffraction, was also confirmed. All the experimental results can be explained reasonably by assuming that the low temperature phase of magnetite has monoclinic symmetry, and the space group is either C s 4 - C c or C 2 h 6 - C 2/ c .
TL;DR: In this paper, a new soft-mode, belonging to the B 2 representation, has been observed by means of Raman scattering experiment in the ferroelectric phase below T 3 (93 K) of K 2 SeO 4.
Abstract: In the ferroelectric phase below T 3 (93 K) of K 2 SeO 4 a new soft-mode, belonging to the B 2 representation, has been observed by means of Raman scattering experiment. This mode is different from the soft A 1 mode previously reported to soften as T 2 (129.5 K) was approached from below. The frequency of this newly observed mode is abotut 13.2 cm -1 at 9.8 K, and decreases as the temperature increases. The observed result is discussed in connection with the successive phase transitions in the K 2 SeO 4 crystal.
TL;DR: In this article, it was observed for Fe 3 O 4 that the presence of residual stresses lowers the so-called Verwey temperature, T v, considerably, broadens the temperature-width of the anomalous specific heat at T v and decreases the discontinuous conductivity change at T V.
Abstract: It was observed for Fe 3 O 4 that the presence of residual stresses lowers the so-called Verwey temperature, T v , considerably, broadens the temperature-width of the anomalous specific heat at T v , produces another additional peak and decreases the discontinuous conductivity change at T v . The entropy change at the phase transition was determined to be 5.4 J /mole·deg but when the effect of short range order is included it becomes 9.6 which is much larger than the value expected for electron hopping under the Anderson's restriction. The anisotropic conductivity was measured below T v along the monoclinic axes a , b and c . The magnitude of conductivity was in the order of σ c >σ b >σ a in the range of T v > T >60 K, while it changed to σ b >σ a >σ c below 60 K. The conductivity along [\bar111], or the longest , was also measured by using a squeezed crystal in which a monoclinic single domain is realized. This direction was least conductive among four 's in the whole temperature range.
TL;DR: In this paper, two complementary pictures for the resonance Raman scattering are presented, corresponding to two different ways of decomposing the four-time correlation function of dipole moment for this second-order process into a pair of two-times correlation functions.
Abstract: Two complementary pictures for the resonance Raman scattering are presented, corresponding to two different ways of decomposing the four-time correlation function of dipole moment for this second-order process into a pair of two-time correlation functions. One is to take the auto-correlation of polarizability following the semi-classical picture for Raman scattering and expand it in powers of intra-system coupling; how the Raman spectra of higher orders approach the so-called luminescence is shown in the weak and strong coupling limits. Another is to study the correlation between absorption and emission processes; one can see how the relaxation of the strong coupled system after photoexcitation is reflected in the time-resolved emission spectra.
TL;DR: The effect of magnetic field on the transition curve of monoclinic TaSe 3 was found to be superconducting below 2.1 K as mentioned in this paper, which is anisotropic.
Abstract: Monoclinic TaSe 3 was found to be superconducting below 2.1 K. The effect of magnetic field on the transition curve is very anisotropic. One-dimensional behavior is expected.
TL;DR: The Raman spectra in potassium selenate single crystal were measured over the temperature range 77∼300 K and the relationship between the soft-mode and the phase transition was discussed in this paper.
Abstract: The Raman spectra in potassium selenate single crystal were measured over the temperature range 77∼300 K. The spectra contain components due to internal vibrations of selenate radicals in the frequency region 300∼900 cm -1 , and those due to external lattice vibrations in the region 0∼200 cm -1 . The soft-mode was observed whose frequency decreases as the transition point T 1 (129.5 K) is approached from below. On the basis of these results the relationship between the soft-mode and the phase transition is discussed.
TL;DR: In this paper, the magnetic susceptibility of vanadium was measured in the temperature range between 1.6 to 300 K and the C-W component of the susceptibility increases with the decrease of particle size as the inverse of average diameter, suggesting that the magnetic moment which revealed the Curie-Weiss type susceptibility originates from the surface region of the particle.
Abstract: Hyperfine particles (100 to 1000 A) of vanadium were prepared by the evaporation method and the magnetic susceptibility of these fine particles was measured in the temperature range between 1.6 to 300 K. The magnetic susceptibility of these fine particles was found to consist of two parts, one was the Pauli type which was also observed in the bulk state of the metal and the other was the Curie-Weiss type overlapping the temperature independent one. The C-W component of the susceptibility increases with the decrease of particle size as the inverse of average diameter, suggesting that the magnetic moment which revealed the Curie-Weiss type susceptibility originates from the surface region of the particle. Localization of 3d-electron at the surface of particle is a probable origin of the magnetic moment.
TL;DR: In this article, a molecular model is applied to explain the vibrational spectra of amorphous and crystalline GeSe 2 and it is shown that amorphus may have the same local order as crystalline geSe 2.
Abstract: Raman scattering and infrared absorption measurements have been performed on amorphous Ge x Se 1- x with 0≦ x ≦0.4 and crystalline GeSe 2 . Molecular model is applied to explain the vibrational spectra of amorphous GeSe 2 . Variation of Raman spectra in Ge x Se 1- x glasses with Ge composition shows that local order is not largely changed with the glass composition. The vibrational spectra, particularly infrared absorption spectra, of amorphous and crystalline GeSe 2 are very similar; suggesting that amorphous GeSe 2 may have the same local order as crystalline GeSe 2 .
TL;DR: In this article, the phase transitions of the charge density wave (CDW) state in 1T-TaS 2 were studied both theoretically and experimentally, and the positions and intensities of the fundamental and third-order harmonic frequencies were analyzed.
Abstract: The phase transitions of the charge density wave (CDW) state in 1T-TaS 2 are studied both theoretically and experimentally. The positions and intensities of the fundamental and third-order harmonic...