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Kazuhiro Nozaki, Naoaki Bekki
1984 Volume 53 Issue 5 Pages
1581-1582
Published: May 15, 1984
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It is shown that the 1-D generalized Ginzburg-Landau equation has a solitary wave solution, a hole solution and a shock-type solution. In the absence of a linear dispersion, we have another exact solution showing that the collision of two shock-type waves results in the formation of the hole.
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T. P. Pandya, L. M. Bali, (Ms) S. Roy
1984 Volume 53 Issue 5 Pages
1583-1586
Published: May 15, 1984
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Single particle dynamics in free electron laser is discussed with the help of Lorentz force equation. The treatment gives a small gain term “on resonance” where previously no gain was found by Colson.
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Yutaka Sasakura
1984 Volume 53 Issue 5 Pages
1587-1589
Published: May 15, 1984
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The instability of the heterogeneous rotating flow in an azimuthal magnetic field is investigated for the flute-mode disturbance. Both the density ρ
0 and the magnetic field intensity
H0⁄
r divided by the radial distance are assumed to have non-negative radial gradients. It is shown that the complex angular phase-velocity for any unstable flute-mode must lie within the semicircle in the upper half-plane which has
\sqrt(
b−
a)
2−4(
Va2⁄
r2)
mfor diameter. If the square of this expression is negative the rotating flow is stable. Here a and b are, respectively, the lower and the upper bound of angular velocity of the rotating flow,
Va(
r) is the Alfvén velocity and the suffix m means the minimum value.
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Reiji Sugaya, Hideki Fujita, Isamu Ogawa
1984 Volume 53 Issue 5 Pages
1590-1593
Published: May 15, 1984
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We have observed experimentally damping and growing of fast and slow space charge waves of an electron beam due to nonlinear Landau damping in an electron beam-plasma system by using spectrum analysis. The former with positive energy damps and the latter with negative energy grows by nonlinear interaction with the Trivelpiece-Gould mode and the electron beam. The lowest and higher modes of the Trivelpiece-Gould modes with respect to a radial wavelength grow by this nonlinear wave-particle interaction satisfying the resonant condition.
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Mitsuhiro Nambu
1984 Volume 53 Issue 5 Pages
1594-1597
Published: May 15, 1984
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The amplification condition of Langmuir wave in the presence of ion wave turbulence is obtained for the Maxwell distribution function of electrons. The physical mechanism responsible for the plasma maser theory is clarified based on high frequency nonlinear forces.
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Hikaru Terauchi, Satoshi Iida, Kazuhiro Tanabe, Hironobu Maeda, Morita ...
1984 Volume 53 Issue 5 Pages
1598-1601
Published: May 15, 1984
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From an EXAFS study of amorphous PbTiO
3 its local structure is determined. The Pb–O and Pb–Ti distances in the amorphous specimen are shorter than those of the ferroelectric PbTiO
3 crystal. The annealing effect of the locally distorted structure is discussed comparing the Raman spectra of the annealed amorphous specimen with those of crystalline PbTiO
3 under high pressure.
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Kazuo Gesi
1984 Volume 53 Issue 5 Pages
1602-1605
Published: May 15, 1984
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The pressure induced ferroelectric II to ferroelectric III phase transitions in Ca
2Sr(C
2H
5COO)
6 (DSP) and Ca
2Pb(C
2H
5COO)
6 (DLP) crystals were reinvestigated by polarizing microscope observation and dielectric constant measurements. The phase transitions were observed without passing through the first order phase boundaries to avoid possible effects of strains. At room temperature transitions from optically uniaxial to biaxial states were found at 0.68±0.10 GPa in DSP and 0.60±0.10 GPa in DLP. Dielectric constant measurements indicated that the transition in DLP corresponds to the II–III transition while that in DSP to a new pressure induced phase of IV. The results indicate that phase III in DLP is not isostructural with phase II in contrast to early expectation.
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Fumio Komori, Satoshi Okuma, Shun-ichi Kobayashi
1984 Volume 53 Issue 5 Pages
1606-1609
Published: May 15, 1984
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Electronic conduction in thick films of Cu and Au is studied. The localization and the interaction effects in three dimension are observed in 2000 A thick films. The crossover of the dimensionality between two and three with thickness and with temperature is discussed.
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Michio Naito, Hironori Nishihara, Shoji Tanaka
1984 Volume 53 Issue 5 Pages
1610-1613
Published: May 15, 1984
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The
181Ta nuclear quadrupole resonance (NQR) study of 1
T-TaS
2 has been made at 4.2 K in the frequency range from 75 MHz to 235 MHz in order to obtain detailed information on the superlattice structure in the commensurate charge density wave state. NQR signals from inequivalent Ta sites are divided into three groups, whose quadrupole frequencies and asymmetry parameters are definitely different from one another. These results are understood on the basis of the star-shaped cluster model including the effect of three-dimensional (3D) ordering of the CDW.
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Eiji Nakamura, Kohji Abe, Kiyoshi Deguchi
1984 Volume 53 Issue 5 Pages
1614-1616
Published: May 15, 1984
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An expression of the thermal expansion for the quasi-one-dimensional Ising model has been derived and applied to the experimental result of CsH
2PO
4 reported in the preceding paper. It is found that the anomalous spontaneous strain in CsH
2PO
4 is explained satisfactorily by the excess term in the thermal strain caused by the intrachain interaction.
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Katsuaki Sato
1984 Volume 53 Issue 5 Pages
1617-1620
Published: May 15, 1984
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Near-normal incidence reflectivity spectra of pyrite type compounds (FeS
2, CoS
2 and NiS
2) have been measured for photon energies between 0.2 and 4.4 eV. By using Kramers-Kronig relations, optical constants (
n and
k) and absorption coefficient have been calculated. Absorption spectra of FeS
2 and CoS
2 thus obtained are in good agreement with those directly measured on thin films. Absorption edge of NiS
2 is located around 0.3 eV, which is very close to 0.37 eV obtained from the absorption spectrum of a bulk crystal. Absorption spectra of FeS
2 and CoS
2 in the energy region of the measurements are interpreted in terms of the band to band transition from the occupied
t2g states to the unoccupied
eg states derived from the transition metal ions of these compounds.
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Katsuyuki Inabe, Shoichi Nakamura, Nozomu Takeuchi
1984 Volume 53 Issue 5 Pages
1621-1623
Published: May 15, 1984
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Photoacoustic (PA) signals due to the F centers formed by additive coloration are observed with a microphone-detection method. The result indicates that the PA signal is initially proportional to the optical absorption coefficient. Among several paths of de-excitation of the F centers, the non-radiative transition is considered to be mainly responsible for the PA signal. It is also confirmed that the saturation of the PA signal occurs at around the absorption coefficient refer to the optical thickness equivalent to the thermal thickness of the crystal.
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Akira Sugiyama
1984 Volume 53 Issue 5 Pages
1624-1633
Published: May 15, 1984
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A general and practical technique is proposed for lattice sum of long-range pair interaction potentials. As Ewald did, a pair potential is expressed by a sum of two terms; the one is a function of a vector
r in real crystal space and the other is that of a vector
q in reciprocal space and these functions converge rapidly to zero as
r→∞ and
q→∞, respectively.
The present method finds appropriate transforms by the use of usual mathematical tables of Fourier transforms. For coulomb potential, the method derives many practical variations of the traditional Ewald transform. For pair potentials discussed in the pseudopotential theory, the method gives transforms useful for rapid convergence of lattice sums. In addition the method gives a simple estimation of errors in lattice sums due to cut-off at a finite term.
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Masayoshi Tajiri, Mari Hagiwara
1984 Volume 53 Issue 5 Pages
1634-1642
Published: May 15, 1984
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The three-dimensional nonlinear Schrödinger (3D-NLS) equation is reduced first to the 2D-Klein-Gordon equation, secondly to the 1D-NLS equation and finally to the second Painlevé equation by similarity transformations. It is also shown that the 3D-NLS equation has N-soliton solutions which are not parallel propagating solutions.
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Isao Harada
1984 Volume 53 Issue 5 Pages
1643-1651
Published: May 15, 1984
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Exact results for the thermodynamic properties of the one-dimensional classical planar model with competing nearest-neighbor and next-nearest-neighbor interactions are presented. The calculations are performed by extending the numerical transfer-matrix method of the nearest-neighbor problem to allow for next-nearest-neighbor interactions. It is found that, for a certain range of values of the competing interactions, the system exhibits helical short-range order whose characteristic wave-number depends on temperature. The nature of the helical short-range order at low temperatures is discussed in connection with a domain wall between domains of opposing chirality of the helical state.
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Fumihiko Tanaka
1984 Volume 53 Issue 5 Pages
1652-1659
Published: May 15, 1984
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This paper derives a new model describing sterically interacting polymers in a solution, a finite fraction of which forms closed rings. The model is closely related to a magnetic partition function for classical spin model, but vanishing limit (
n→0) for the internal degrees of freedom is not assumed. For given average molecular weights and amounts of ring and chain fractions, the number of spin components is uniquely determined. The osmotic pressure and the single chain end-to-end distance are obtained in the case of an athermal solvent. The effect of ring formation is discussed.
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Kazuyosi Ikeda, Kunisuke Nisizima
1984 Volume 53 Issue 5 Pages
1660-1666
Published: May 15, 1984
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We describe
formal diagrams (with their
values) derived by the bending of
prototypes consisting of eight or less points connected together by bonds of equal length for the three-dimensional (simple cubic), the two-dimensional (square) and the one-dimensional lattice.
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Motohiko Nagano, Yoshikazu Hatano, Tadao Hara, Naoaki Hayashida, Setsu ...
1984 Volume 53 Issue 5 Pages
1667-1681
Published: May 15, 1984
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Lateral distribution of electrons is determined with scintillators of 50 and 3 mm thickness from the core to 500 m in the Akeno array. Lateral distribution can not be represented by the NKG function with a single age parameter. From size and depth dependence of age parameter and its fluctuation at fixed muon size, elongation rate and fluctuations in the depth of shower maximum are estimated and discussed.
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Norihiko Nakauchi
1984 Volume 53 Issue 5 Pages
1682-1691
Published: May 15, 1984
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Equations of energy spectra in homogeneous axisymmetric turbulence are formulated by applying the modified zero-fourth-cumulant approximation and numerically solved under the three different initial conditions: (A) three-dimensional anisotropic turbulence; (B) two-dimensional isotropic velocity fluctuations transverse to the direction of axisymmetry λ; (C) one directional homogeneous fluctuations parallel to λ. The results show that in the case (A) Herring’s over-relaxation is observed, and that in the case (B) an inverse energy cascade characteristic of two-dimensional isotropic turbulence is observed. Also, it is shown that for strongly anisotropic cases (B) and (C) an approach to isotropy is much slower than for less anisotropic case (A).
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Muhammad Umar Farooq, Sinzi Kuwabara
1984 Volume 53 Issue 5 Pages
1692-1701
Published: May 15, 1984
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An iterative-integral scheme based on transformation of the Navier-Stokes and continuity equations into integral equations is developed to the steady two-dimensional, viscous incompressible flows in terms of stream function and vorticity. Integral representations of the stream function and vorticity are obtained by use of Green’s functions. An integral equation for the boundary vorticity is derived with these representations. The recirculating flow, occuring inside a rectangular cavity by the steady movement of one of its walls, is computed. Numerical results are obtained for Reynolds numbers R of 0, 32, 64 and 100. This approach has the advantage of getting direct solutions at R=0 and rapid convergent solutions at other Reynolds numbers.
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Muhammad Umar Farooq, Sinzi Kuwabara
1984 Volume 53 Issue 5 Pages
1702-1711
Published: May 15, 1984
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A computational method for the solutions of the time-dependent Navier-Stokes equations in their stream function and vorticity formulation, is developed. Integral representations of stream function and vorticity and an integral equation for the time-dependent boundary vorticity, are obtained by use of Green’s functions. A two-dimensional flow in a rectangular cavity is considered, assuming that the fluid is at rest initially and the upper wall is set in motion at
t=0. The discretization procedure is applied to solving the integral equations. Numerical solutions of transient state reaching the steady one are presented for Reynolds numbers
R of 0, 100 and 200.
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Shoichi Wakiya
1984 Volume 53 Issue 5 Pages
1712-1717
Published: May 15, 1984
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An alternative representation of Pell and Payne’s solution for a torus in a uniform stream is given and using this the structure of flow near the hole of the torus is examined, particularly when the size of the hole is very small. When the hole radius is about 0.092 times the radius of a base circle making the torus by rotation, a vortex ring begins to grow on the axis of symmetry of the flow. As the hole size is decreased, such eddy regions form alternately on the torus and the symmetry axis.
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Shigenobu Itoh
1984 Volume 53 Issue 5 Pages
1718-1727
Published: May 15, 1984
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The permeability of a fibrous material is discussed. The material is assumed to be an assemblage of parallel infinite cylindrical rods fixed at random in space. A statistical formulation developed by Lundgren is applied to the system. When a conditional average is considered, a mean number of the rods in contact with a certain point decreases as the point approaches to a test rod. This particular region is called an intermediate layer. Here the permeability is determined as a function of the radius
a, and the volume fraction
c, of the rods by taking into account of the layer. Two typical cases, a longitudinal flow past the rods and a transverse one, are considered. The Galerkin method is used to obtain approximate solutions of these flows. We found that the permeability for the transverse flow through random array of rods is smaller than that through spheres for
c\gtrsim0.5.
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Masaki Takashima, Hiromitsu Hamabata
1984 Volume 53 Issue 5 Pages
1728-1736
Published: May 15, 1984
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Linear stability theory is applied to examine the effect of a horizontal ac electric field on the stability of natural convection which occurs in a dielectric fluid between two parallel vertical plates maintained at different temperatures. The power series method is used to obtain the eigenvalue equation which is then solved numerically. It is shown that when the electrical Rayleigh number
L (defined in the text) is less than about 2130 the electric field has no effect on the stability of natural convection, and that when
L exceeds this value the electric field and the natural convection flow are coupled strongly and they exhibit a complicated but interesting effect on the stability of the system. A rough criterion is given for applicability of the power series method to the present problem.
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Toshihisa Honma, Masafumi Kito, Ikuo Kaji, Ichiro Fukai
1984 Volume 53 Issue 5 Pages
1737-1745
Published: May 15, 1984
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In the toroidal coordinates, a stability analysis is presented for very low-aspect-ratio tokamaks with circular cross section which is described by a surface current model (SCM) of axisymmetric equilibria. The energy principle determining the stability of plasma is treated without any expansion of aspect ratio. Numerical results show that, owing to the occurrence of the non-axisymmetric (
n=1) unstable modes, there exists no MHD-stable ideal SCM spheromak characterized by zero external toroidal vacuum field. Instead, a stable spheromak-type plasma which comes to the ideal SCM spheromak is provided by the configuration with a very weak external toroidal field. Close to the spheromak regime (1.0<aspect ratio\lesssim1.1), the minimum safety factor and the critical β-values increase monotonically with aspect ratio decreasing from a large value, and curves of β
p versus β in the marginal stability approach to an ideal SCM spheromak line β
p=β.
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Shunjiro Shinohara, Nobuyuki Asakura, Masahiro Naito, Kenro Miyamoto
1984 Volume 53 Issue 5 Pages
1746-1752
Published: May 15, 1984
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Antenna loading resistance and electron heating effects of ICRF wave were investigated in TNT-A tokamak. Lodaing resistance increased with the mean plasma density and decreased with the input power. The effect of the distance between the plasma and antenna surface on loading resistance was studied and had good agreements with the calculated results. The increase in the soft Xray emissivity was larger in the presence of ion-ion hybrid and/or ion cyclotron resonance layer in the plasma than that in the absence of them. With the absorbed power up to two times of the ohmic power, the central electron temperature increased by 20%, the soft Xray emissivity increased by 80% and the mean plasma density decreased by 10%, while the total radiation loss increased slightly (by 15%).
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Tadatsugu Hatori, Yoshihiko Abe
1984 Volume 53 Issue 5 Pages
1753-1758
Published: May 15, 1984
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Self-consistent states of plasma interacting adiabatically with the high frequency fields are examined numerically, with special regards to rf-plugging of sheet plasma.
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Kimitaka Itoh, Sanae-Inoue Itoh, Takashi Tuda, Shinji Tokuda
1984 Volume 53 Issue 5 Pages
1759-1774
Published: May 15, 1984
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The kinetic theory of the global
n=1 instabilities of finite-pressure tokamak plasmas with circular cross-section is investigated in collisionless limit (
m,
n: poloidal and toroidal mode numbers). Wave-particle interactions and finite gyroradius effect are included. The radial-poloidal eigenmode equations are directly solved numerically. The
m=1 internal/tearing mode,
n=1 ballooning mode and
m=2 tearing mode are identified with a fixed boundary condition. The
m=1 internal mode turns out to be the collisionless tearing mode in low pressure regimes. The pressure driven ballooning mode is connected with the electrostatic-like ballooning mode. The toroidal coupling further stabilizes the
m=2 tearing mode, which is destabilized by the parallel current and can be stabilized by coupling with drift branch. Analytical studies are made by using the energy integral.
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Kêitsiro Aizu
1984 Volume 53 Issue 5 Pages
1775-1782
Published: May 15, 1984
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Although the transition sequence [prototypic phase→incommensurate nonferroelectric phase→commensurate ferroelectric phase] is more common, the transition [prototypic phase→incommensurate ferroelectric phase] is also possible. A thermodynamical theory of this transition is presented. Ammonium Rochelle salt is dealt with as an example. Not only the soft order parameters having wavevector (1/2, 0, 0) for translational transformations, but also a hard order parameter transformed like the (
y,
z) component of strain is taken into account. Their cooperation is important. It is found that, if the coefficients in the free energy function satisfy certain inequalities, the prototypic phase is changed to an incommensurate ferroelectric phase earlier than to any other ferroic phase.
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Kazuhide Tanaka, Yuh Yamada, Kenzo Kai, Kenji Suzuki
1984 Volume 53 Issue 5 Pages
1783-1789
Published: May 15, 1984
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Electronic states in Zr–Ni and Zr–Ni–D alloy glasses are studied over wide ranges of nickel and deuterium concentrations by measuring Zr Lβ
2,15 and Ni Lα
1,2 emission bands. Zirconium Lβ
2,15 is modified deep in the band while Ni Lα
1,2 undergoes a minor change near the Fermi edge. These spectra suggest that chemical bonding among constituent atoms affects the band structures of the glasses significantly. A sign of preference for Zr–D bonding to Ni–D bonding is observed and its effect on the band structure is discussed.
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Toshiro Tani, Shoji Tanaka
1984 Volume 53 Issue 5 Pages
1790-1796
Published: May 15, 1984
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The temperature dependence of Seebeck coefficient of 1T-TaS
2 is observed in the nearly-commensurate charge-density wave phase with simultaneous measurement of resistivity. Seebeck coefficient is mainly negative and shows complicated behaviors with large hysteresis. At about 280 K in the heating process, we found distinctive anomalies both in Seebeck coefficient and in resistivity, which may correspond to the new phase transition found in the thermal expansion measurement recently. The possible electronic structures in the nearly-commensurate phase are discussed on the basis of the Seebeck effect observations.
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Chang-Gen Jiang, Hidetoshi Namba, Michio Nagasaka, Nobuhiro Kosugi, Sh ...
1984 Volume 53 Issue 5 Pages
1797-1801
Published: May 15, 1984
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Ion-neutralization and ion-molecule reaction of N
+ with CO molecules adsorbed on Ni(100) and Cu(100) have been studied at the ion energy of 10 eV. In the N
+-CO/Ni(100) system, no product ion was observed and the ion-neutralization process was found to be dominant. In the N
+-CO/Cu(100) system, O
+ and CO
+ were detected and the ion-neutralization cross section was found to be much smaller than that in N
+ on CO/Ni(100). These results are explained by the different magnitude of the back donation in the chemisorption bond of CO on metals. This explanation is supported by observing the N
+ collision on CO/K/Cu(100).
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Kazuhiko Yamashita
1984 Volume 53 Issue 5 Pages
1802-1808
Published: May 15, 1984
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The explicit expression for the magnetic field, electric field, current density and charge density are presented in the transient superconducting system which has layered singularities. Time- and space-dependence of the magnetic field and the electric field in the superconductors with layered singularities to which external magnetic field is applied at
t=0 is estimated by means of the computer calculation and the computer graphics.
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Katsurou Hanzawa, Tadao Kasuya
1984 Volume 53 Issue 5 Pages
1809-1818
Published: May 15, 1984
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The existence of an antiferro-quadrupolar ordering in the intermediate temperature region in CeB
6 is suggested by a model calculation. CeB
6 has two transition temperatures,
Tm=3.3 K and
TN=2.3 K, enabling us to define three phases I, II and III in the sequence of decreasing temperature. The phase II shows unusual properties: A weak antiferromagnetism is induced and enhanced by the external magnetic field in the phase II, making the I–II phase boundary shift to the high-temperature side with increasing field. These properties can be explained by the present model based on the combined effect of the crystal field and the antiferro-quadrupolar interaction among 4f electrons on Ce
3+ ions. The molecular-field approximation with the two-sublattice model is used. Detailed comparison is made with experiment for various thermal and magnetic quantities.
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Hideoki Kadomatsu, Makio Kurisu, Hiroshi Fujiwara
1984 Volume 53 Issue 5 Pages
1819-1827
Published: May 15, 1984
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Measurements of electrical resistivity, ac magnetic susceptibility and magnetization of PrAg were carried under pressures up to 17 kbar, in a temperature range from 2.3 K to 300 K and in fields up to 20 kOe. At ambient pressure, the Néel point
TN and the Curie point
Tc are 10.6 K and 7.8 K, respectively. When pressure
p increases,
TN is almost constant, while
Tc increases largely, coincides with
TN around 7 kbar and is almost constant at pressure up to critical pressure
pc\simeq10 kbar, where structural transition
TM appears. At
pc,
TN and
Tc values become 13 K and 7 K, respectively. With further increasing
p,
TM increases and
Tc decreases drastically while
TN slightly decreases. The spontaneous magnetization increases almost linearly with increasing
p, reaches a maximum value near
pc and then decreases very rapidly above
pc.
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Fusayoshi J. Ohkawa
1984 Volume 53 Issue 5 Pages
1828-1836
Published: May 15, 1984
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A possibility is pointed out that two or more than two conduction bands play a role in metallic valence fluctuating systems; the dispersion relations of the conduction bands have the same sign of tangent in the proposed model. The separation between conduction bands is one of essential parameters characterizing the system; the effective mass of quasi-particles is an increasing function of the separation. A possibility is discussed that the density of states has a camel back structure around the chemical potential. There is also a peak around unrenormalized
f levels. The effect of dilution of
f sites, for example, the replacement of Ce atoms by La ones, on the resistivity is investigated. The residual resistivity is higher, as the separation between conduction bands is larger.
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Takaharu Abe
1984 Volume 53 Issue 5 Pages
1837-1846
Published: May 15, 1984
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The magnetization of (Y
1−xGd
x)Ni
3 (0≤
x≤0.05) at 6.2 kOe was studied in the temperature range between 4.2 and 295 K. The measurements indicate that the magnetic moments of the Gd ions and the itinerant electrons are coupled antiferromagnetically. The samples for
x≥0.033 have compensation points. The magnetization curve for each sample crosses with the curve for the host material at about 60 K. The observed magnetization is analyzed on the basis of the
s-
f exchange model. By the molecular field approximation applied to the temperature dependence of the magnetization, the value, −0.02 eV, is obtained for the
s-
f exchange integral
J. The amount of the induced moment due to Gd atoms extrapolated to
T=0 K is 1.3 μ
B per Gd atom. The existence of a new characteristic temperature
T* in the paramagnetic region is predicted theoretically. The experimental result agrees with the prediction.
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Masayuki Itoh, Hiroshi Yasuoka, Yutaka Ueda, K\={o}ji Kosuge
1984 Volume 53 Issue 5 Pages
1847-1856
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Using a single crystal of a substance showing the metal-insulator transition, V
6O
13, the microscopic magnetic properties in the metallic, insulating and antiferromagnetic states have been investigated by means of the pulsed NMR technique. In the metallic state the Knight shift and the nuclear-spin lattice relaxation time
T1 were measured in order to clarify the properties of spin fluctuations in the narrow
d-bands. It was found that
T1 has the temperature dependence as 1⁄
T1=α+β
T. The α term is attributed to the
d-spin fluctuations, while the β term is due to the Korringa process. At
Tt≈150 K, a half of the V
4+ sites takes singlet spin-pairs resulting in the decrease of the magnetic susceptibility. In the antiferromagnetic state, the magnetic structure was determined as such that the antiferromagnetic spin moments are parallel to the
b-axis.
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Mitsuhiro Motokawa, Akihiro Otsuka, Chiaki Uyeda, Muneyuki Date
1984 Volume 53 Issue 5 Pages
1857-1862
Published: May 15, 1984
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The shift and width of electron spin resonance line of TMMC are measured in a pulsed high magnetic field by using submillimeter wave of HCN laser (λ=0.337 mm or ν=891 GHz) between helium temperature and 110 K. The resonance field shifts by 4 kOe from
g=2 line in antiferromagnetic state. The shift shows a maximum as large as 6 kOe at 12 K and decreases as the temperature increases but is still 3 kOe even at 110 K. Such large shifts in the paramagnetic state are not explained.
The Néel temperature is determined to be 3.5 K at 322 kOe from the anomaly of linewidth. It is fairly high compared to 0.835 K at 0 field, but is reasonable from the consideration of cross-over effect of spin dimensionality.
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Katsuhiko Hasebe, Hiroyuki Mashiyama, Sigetosi Tanisaki, Kazuo Gesi
1984 Volume 53 Issue 5 Pages
1863-1865
Published: May 15, 1984
Released on J-STAGE: June 01, 2007
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The space groups of six phases of {N(CD
3)
4}
2CoCl
4 were determined by X-ray diffraction as
Pmcn(
Z=4), incommensurate,
P2
1cn(
Z=20),
P112
1⁄
n(
Z=12),
P12
1⁄
c1(
Z=4) and
P2
12
12
1(
Z=12), respectively in the order of decreasing temperature. The deuteration causes the increase of the modulation wavenumber. This increase of the wave number agrees qualitatively with that expected from the distribution of modulation wavenumber in the reduced
p-
T phase diagram.
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Katsuhiko Hasebe, Hiroyuki Mashiyama, Sigetosi Tanisaki, Kazuo Gesi
1984 Volume 53 Issue 5 Pages
1866-1868
Published: May 15, 1984
Released on J-STAGE: May 29, 2007
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The space group of each low temperature phase in {N(CH
3)
4}
2ZnBr
B and {N(CH
3)
4}
2CoBr
4 was determined by X-ray diffraction as
P12
1⁄
c1. The characteristic diffuse streaks along the
b*- and
c*-directions were observed in the high temperature phase in both materials.
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Yosuke Kayanuma, Susumu Fukuchi
1984 Volume 53 Issue 5 Pages
1869-1877
Published: May 15, 1984
Released on J-STAGE: June 01, 2007
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Nonradiative transitions in the deep impurity states in semiconductors are studied by a semiclassical model, in which the lattice distortion around the impurity is approximated as a classical harmonic oscillator modulating the potential depth for the electron. An integral equation is derived and solved numerically describing the nonadiabatic transition from the bound state to the scattering states which corresponds to the thermal ionization. Peculiar features in the transition dynamics are clarified in contrast with the transitions between discrete levels. In the adiabatic limit, which covers the situation at high temperatures in real semiconductors, the transition rate obeys the Arrhenius law with the pre-exponential factor given by the phonon frequency as pointed out by Sumi.
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Takenori Higashimura, Hiroyuki Nakatani, Minoru Itoh, Ken-ichi Kan&rsq ...
1984 Volume 53 Issue 5 Pages
1878-1887
Published: May 15, 1984
Released on J-STAGE: June 01, 2007
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Temperature dependence of the intensities of 5.88 eV (
Near-Edge) and 2.64 eV (
Blue-Green) emission bands in KCl: I has been investigated in crystals containing various amount of iodine impurities under excitation into each of three absorption bands due to isolated I
− ions. Localized excitons created on the I
− monomer sites have two relaxed states, NE-state (
one-center type) and BG-state (
two-center type). It is confirmed that there is a thermal activation process from the NE-state to the BG-state. Fraction of the relaxation rate into the BG-states, γ
BG, is found to increase with increasing iodine contents. This means that the relaxation mechanism of the localized exciton is influenced markedly if another iodine ion is present in the vicinity of the localized exciton.
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Hidetoshi Namba, Yoshitada Murata
1984 Volume 53 Issue 5 Pages
1888-1898
Published: May 15, 1984
Released on J-STAGE: May 29, 2007
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Surface electronic and vibrational properties of “fine” and “defective” MgO(100) surfaces have been studied by secondary electron emission spectroscopy applying the electron time-of-flight method and cathodoluminescence spectroscopy under ultra-high vacuum. The energies of the bottom of the conduction band and a level related closely to the F center in MgO are determined to be 4.0 and 1.6 eV above the vacuum level, respectively. Work function, which is the energy difference between the vacuum level and the top of the valence band, of MgO is determined to be 3.8 eV. In the “defective” crystal, the phonon side band due to electron-phonon coupling is resolved around the extra peak at 1.6 eV in the secondary electron emission.
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Masashi Ban, Toshihico Arimitsu
1984 Volume 53 Issue 5 Pages
1899
Published: May 15, 1984
Released on J-STAGE: May 29, 2007
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