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Naoshi Suzuki
1976 Volume 40 Issue 5 Pages
1223-1231
Published: May 15, 1976
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A general theory of Raman scattering in a magnetic crystal due to excitation of one phonon and simultaneous excitation of the spin system is developed. Within the molecular field approximation in the case of a ferromagnet it is predicted that the Raman intensity increases with increasing temperature and attains a constant value at temperatures higher than
Tc and that the Raman line has a broad linewidth that corresponds to the whole phonon frequency range in the Brillouin zone. The theory is applied to the “broad Raman line” observed in EuS. The observed temperature dependence of the Raman intensity is qualitatively explained and the calculated Raman line shape with phonon frequencies obtained on the basis of the shell model agrees well with the observed one.
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Tetsuo Nakanishi
1976 Volume 40 Issue 5 Pages
1232-1239
Published: May 15, 1976
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By using a stochastic model of a certain autocatalytic chemical system, the characteristic behaviour of fluctuation is analyzed in relation to the distance from equilibrium. A sample process of fluctuation around a stationary state is traced by means of computer simulation. The characteristic behaviour of fluctuation and of the reaction process hidden in fluctuation are investigated by the statistical analysis of this sample process. Following results are obtained: Probability density distribution is Poisson’s at equilibrium. As the value of affinity becomes large, the distribution is deformed from Poisson’s. In the range of frequency high enough, intensity of the frequency spectrum of fluctuation is a constant independent of the value of affinity. The fluctuation processes of each molecule are statistically independent each other at equilibrium. As the value of affinity becomes large, those processes have statistically intimate dependency.
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Sei-ichi Takase
1976 Volume 40 Issue 5 Pages
1240-1243
Published: May 15, 1976
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The static properties are investigated by computer simulation for the square Ising ferromagnet in which the nearest-neighbor interactions are ferromagnetic and the second interactions antiferromagnetic. Energy and magnetization at various temperatures are obtained by Monte Carlo calculations performed on the lattice with 20×20 spins. The Curie point determined as the inflection point of the energy-vs-temperature curve agrees with the result by Fan and Wu rather than other analytical approximations. The behavior of the spontaneous magnetization
M0(
T) for
T→
Tc−0 as characterized by the critical exponent β is shown by comparing the data with an analytical equation for the magnetization. The exponent β remains probably unchanged from the original value 1/8.
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Duk Joo Kim
1976 Volume 40 Issue 5 Pages
1244-1249
Published: May 15, 1976
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The effect of the exchange interaction between electrons on the electron-phonon interaction in metals is studied within the generalized random phase approximation. The phonon frequency of a metal is found to be closely related to the magnetic susceptibility of the metal. The sound velocity of the jellium model, for instance, is inversely proportional to the square root of the paramagnetic spin susceptibility. In particular, in the jellium model the occurrence of a charge density wave and a spin density wave is found to be simultaneous. Finally, the electron-phonon coupling constant λ is found to be enhanced significantly by the exchange interaction.
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Duk Joo Kim
1976 Volume 40 Issue 5 Pages
1250-1255
Published: May 15, 1976
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The critical behavior of sound propagation above
Tc in ferromagnetic metals in studied from an itinerant electron model with the generalized random phase approximation. First, by using the Feynman diagrammatic method, the phonon frequency of a metal, both above and below
Tc, is related to the magnetic properties of the metal. Then, in the jellium model the velocity
s and attenuation α
q of sound above
Tc is found to be simply related to the paramagnetic spin susceptibility, χ
mm, respectively as,
s∝χ
mm−1⁄2 and α
q∝χ
mm. When the temperature is very close to
Tc, however, above simple behavior of
s and α
q breaks down owing to the increased imaginary part of the phonon frequency. At
Tc,
s does not vanish and correspondingly α
q does not diverge.
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Takeshi Imamura, Kiyomi Okamoto, Munetaka Saito, Mieko Ohtsuka
1976 Volume 40 Issue 5 Pages
1256-1262
Published: May 15, 1976
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Excess conductivity due to fluctuations above the superconducting transition temperature
Tc in two-dimensional systems is studied both theoretically and experimentally. Theoretically a small correction term added to the Maki-Thompson (MT) term is proposed. This correction term becomes not less important at relatively high temperatures. Experimental results on thallium films are as follows: (1) In the zero electric field limit excess conductivity is well described as the sum of the Aslamazov-Larkin (AL) and MT terms when
T is close to
Tc. However at relatively high temperatures, η\gtrsim0.1 (η=ln(
T⁄
Tc)), the contribution from the above-mentioned correction term is observed. (2) An empirical relation between the pair-breaking parameter δ and
RNsq was found to be δ=δ
0+
const×
RNsq. (3) When η is small excess conductivity in finite electric field is well expressed as the sum of the nonlinear AL and MT terms. (4) The characteristic electric field is observed to be proportional to η
3⁄2.
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Shinji Wada
1976 Volume 40 Issue 5 Pages
1263-1270
Published: May 15, 1976
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The nuclear spin-lattice relaxation times
T1’s and the Knight shift of
93Nb in 2H–NbSe
2 in a single crystal and powdered samples have been measured at 10 MHz and at low temperatures. The Knight shift contains both isotropic and anisotropic terms. The isotropic Knight shift,
Kiso=−0.03(%), is decomposed into the core-polarization part,
Kd=−0.66(%), and the orbital part,
Korb=+0.63(%). In normal state,
T1 obeys a relation,
T1T=65±10 msecK and shows no strong anisotropy. The dependence of
T1 on the symmetry properties of the conduction wave functions is discussed. It is concluded that the admixture of
d3z2−r2 orbit dominates at the Fermi level and
T1 of
93Nb is dominated by the core-polarization interaction. In the superconducting state
T1 varies exponentially as in the case of bulk BCS superconductor with energy gap of 3.5
kBTC.
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Tadao Ezaki, Kaoru Yamafuji, Fujio Irie
1976 Volume 40 Issue 5 Pages
1271-1277
Published: May 15, 1976
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In the resistive state of current-carrying type-2 superconducting cylinders with longitudinal magnetic fields, the existence of a helical structure composed of the flux-flow domain and the normal-like domain has been suggested experimentally.
Based on this helical structure, the expressions of the induced electric field and the induced paramagnetic magnetization are derived with the aid of the critical-state model. The present derivations are applicable only when the magnetic field generated by a transport current is smaller than the longitudinal magnetic field, and the results show fairly good agreements with the observed data of this range.
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Keiichi Kakuno, Yasuo Gondo
1976 Volume 40 Issue 5 Pages
1278-1287
Published: May 15, 1976
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Dynamic behaviors of the magnetization ripple in magnetic thin films are studied by means of solving the Landau-Lifshitz-Gilbert equation of motion numerically. In solving the equation, the exchange interaction and the magnetostatic interaction due to the spatially inhomogeneous distribution of the magnetization in addition to the anisotropy field and the external field are taken into account as the effective magnetic field. The oscillation of the magnetization ripple, caused by the sudden application of driving pulse fields, is excited parametrically and built up remarkably by the varying effective field associated with the rotational motion of the magnetization. It is found that the difference of the rotation angle between the most leading and the most lagging portions can be so large as to reach about 50° in the rotational process of the magnetization.
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Takashi Iwashita, Norikiyo Uryû
1976 Volume 40 Issue 5 Pages
1288-1294
Published: May 15, 1976
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The effects of the biquabratic exchange interaction on the temperature dependence of the magnetic specific heat and sublattice magnetization have been calculated with the use of the spin wave theory for linear chain antiferromagnet. The antiferromagnetic spin structure changes abruptly and begins to make a cant at a certain ratio
Pc of the biquadratic exchange interaction to the Heisenberg one, which is reasonably small enough to appear in the real antiferromagnet with large spin. This change of the spin structure is shown to give significant effects on the magnetic properties.
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Masayuki Shiga, Yoji Nakamura
1976 Volume 40 Issue 5 Pages
1295-1299
Published: May 15, 1976
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The Mössbauer spectra of Fe–Al alloys in the concentration range from 35 to 43 at% Al have been obtained at liquid He temperature. The spectra were analyzed to yield the hyperfine field distribution curves, which are characterized by two distinct peaks indicating the existence of two magnetic states of iron atoms, namely a magnetic state and a nonmagnetic state. It has been revealed that the fraction of the magnetic state, which was estimated from the intensities of two peaks, is comparable to the probability of finding an Fe atom having 4 or more than 4 Fe n.n. The average localized moment has been estimated from the intensity ratio. The average localized moment thus obtained is larger than the spontaneous moment. This fact indicates the existence of antiferromagnetically coupled spins. Correlation between the lattice constant and the magnetic moment is discussed.
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Yuji Yamamoto, Motohiro Matsuura, Taiichiro Haseda
1976 Volume 40 Issue 5 Pages
1300-1304
Published: May 15, 1976
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Magnetic susceptibility and heat capacity of a nearly Heisenberg layer antiferromagnet Cu(HCOO)
2·2(NH
2)
2CO·2H
2O were measured between 1.2 K and 90 K. A broad maximum of the susceptibility associated with the development of short range order was observed near 60 K. A remarkable peak was also found at 15.5±0.1 K, which certainly shows an onset of phase transition at the temperature. Magnetic susceptibility is high temperature region agreed with the calculated one by using high temperature series expansion with
J⁄
K=−33 K. A very small peak of heat capacity was found at 15.45±0.05 K by carefull examination. The extra entropy associated with it was only about 0.006% of the total magnetic entropy R1n2. Comparing these results with those of nearly one and two dimensional Heisenberg antiferromagnets CuCl
2·2NC
5H
5 and Cu(HCOO)
2·4H
2O, we suggest that nearly Heisenberg spin system in two dimensional lattice sets into long range order at a finite temperature
TN with a negligibly small peak of heat capacity.
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Fumihiko Takano, Mamoru Uchinami
1976 Volume 40 Issue 5 Pages
1305-1312
Published: May 15, 1976
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The model expressed by the Hamiltonian
(
Remark: Graphics omitted.),
which is introduced by Inagaki for the discussion of the d-electron system with doubly degenerate orbitals, is investigated by the constant coupling approximation. The result is quite different from that of the molecular field approximation, showing that the effect of the short range order is very important in this system. Especially in the case when all exchange integrals are negative and their magnitudes are slightly different with |
JT|>|
J0|>|
JS|, it is shown that the ferromagnetic ordering in
S occurs first in contrast to the result of Inagaki that the antiferromagnetic ordering in
T occurs first.
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Kazukiyo Nagata, Muneyuki Date
1976 Volume 40 Issue 5 Pages
1313-1320
Published: May 15, 1976
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Antiferromagnetic resonance experiments were performed on several crystals of CuCl
2·2H
2O in which Cl
− ions were partially substituted by Br
− ions. In these systems the antisymmetric exchange interaction of Moriya is nonvanishing in the vicinity of the substitutional Br
− ions and brings about an additional magnetic anisotropy having an axial symmetry about the
b-axis of the crystal. The contribution of the impurity-induced Moriya interaction to the antiferromagnetic resonance parameters
C1 and
C2 is described as
ΔC1=
xD2⁄(2μ
B2) and
ΔC2=0, respectively.
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Junichiro Inoue, Masao Shimizu
1976 Volume 40 Issue 5 Pages
1321-1327
Published: May 15, 1976
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The density of states and local density of states for ferromagnetic Ni–Cu alloys are calculated in the coherent potential approximation. The Hubbard model is assumed and the Hartree-Fock approximation is used. The calculated densities of states for alloys are found to be strongly smoothened out by a rather large potential difference between Ni and Cu atoms. From the calculated results of the density of states, bulk and local magnetic moments and low temperature specific heat coefficient γ are calculated. Moreover, the high-field spin susceptibility at 0 K is calculated. These results are compared with the experimental ones and a qualitative agreement is obtained.
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Ryohei Nakata, Katsuyasu Khono, Minoru Sumita, Eiichi Higuchi
1976 Volume 40 Issue 5 Pages
1328-1332
Published: May 15, 1976
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After thermal-treatment or optical illumination of X-irradiated CaF
2 single crystals, a new ESR signal was observed at room temperature, whose spectrum consists of a single line with
g=2.0013±0.0007. Thermal growth of the center was observed in the temperature range between room temperature and 90°C, and its activation energy was determined as 0.43±0.03 eV, while the decay of the center was observed under subsequent thermal-treatment above 80°C, whose activation energy was 0.63±0.03 eV. Optical illumination on the X-irradiated crystals enhanced the ESR center and maximum response was observed at 380 nm over the wavelength investigated. Thermal properties of the ESR center were interpreted in connection with optical absorption and thermal glow.
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Yuji Ito, Jun Akimitsu
1976 Volume 40 Issue 5 Pages
1333-1338
Published: May 15, 1976
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Direct observation of orbital ordering in the ferromagnet K
2CuF
4 has been made by means of the polarized neutron diffraction technique. The observed interference terms between the aspherical contribution of the spin density distribution and the nuclear contribution from the displaced F
− ions have been satisfactorily explained in terms of the orbital ordering model proposed by Khomskii and Kugel.
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Yasunori Kubo
1976 Volume 40 Issue 5 Pages
1339-1346
Published: May 15, 1976
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The static dielectric function of copper is evaluated for three principal directions of
q, [1, 0, 0], [1, 1, 0], and [1, 1, 1], on the basis of the realistic model. The energy spectra and the wave functions are determined by APW method with the Chodrow potential. The magnitude of the diagonal elements of the dielectric matrix is somewhat larger than the corresponding value of the electron gas owing to the contribution from the d-bands. The non-diagonal elements of the dielectric matrix are also calculated. Some of them are not very small as compared to the diagonal terms.
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Keiichi Iida, Koji Honma, Hideo Okazaki, Shigeru Tamaki
1976 Volume 40 Issue 5 Pages
1347-1350
Published: May 15, 1976
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Atomic structures of liquid Sb–Zn alloys have been measured by the neutron diffraction method. The first peaks of the observed structure factors of the alloys (15, 35, 50 and 60 at % Zn) are split into two maxima. The partial structure factors are obtained from these results on the assumption that they are independent of the concentration of Zn atoms. The total structure factors reproduced from the partial ones are self-consistently in good agreement with the experimental results of the alloys of 15 to 50 at % Zn. The position of the first peak of the pair correlation function g
Sb–Zn(r) is closer to the origin than those of g
Sb–Sb(r) and g
Zn–Zn(r).
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Hiroshi Kamimura, Nevill F. Mott
1976 Volume 40 Issue 5 Pages
1351-1358
Published: May 15, 1976
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The esr-induced decrease in the resistance of doped silicon and germanium for concentrations in the intermediate region is discussed. The model put forward by Morigaki and co-workers, that the effect is due to hot electrons at a mobility edge, is shown to conflict with current ideas about carriers at mobility edges in non-crystalline systems, because the mobility there should decrease with increasing temperature. It is suggested that the carriers at the Fermi energy, which give conduction at low temperature by variable-range hopping, are responsible for the effect. A mechanism for the transfer of the esr energy due to the combined action of the exchange and the spin-orbit interaction is proposed.
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Takashi Iwasaki, Hisawo Wakabayashi
1976 Volume 40 Issue 5 Pages
1359-1362
Published: May 15, 1976
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In the quenched RbF : Mn
2+ crystals, spectrum III
4 (
g=2.006±0.001, |
D|=(108±2)×10
−4 cm
−1,
AMn=−(88±2)×10
−4 cm
−1,
AsF=(11.5±0.4)×10
−4 cm
−1, A
pF=(2.9±0.3)×10
−4 cm
−1) is observed at room temperature being overlapped with spectrum III
2 (
g=2.005±0.001, |
D|=(202±3)×10
−4 cm
−1,
AMn=−(89±2)×10
−4 cm
−1,
AsF=(11.7±0.5)×10
−4 cm
−1,
ApF=(3.0±0.4)×10
−4 cm
−1) at 77 K. The symmetry axes of these spectra coincide with the cubic axis of the crystal. Spectrum III
4 is attributed to Mn
2+-(400) site vacancy pairs ad spectrum III
2 to Mn
2+-(200) site vacancy pairs. The spectrum with axial symmetry in KF is attributed to Mn
2+-(400) site vacancy pairs rather than to (200) site ones.
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Hideyuki Nakagawa, Tetsuya Abe, Hiroaki Matsumoto
1976 Volume 40 Issue 5 Pages
1363-1370
Published: May 15, 1976
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Optical absorption spectra of CdBr
2:I, CdCl
2:I and CdCl
2:Br have been measured at temperatures from 10 to 500 K. In every system, well-defined absorption bands due to doped halogen ions were observed on the low energy sides of intrinsic absorption edges of host crystals. Shapes of these bands are Gaussian around the band maxima and follow Urbach’s rule in the low energy tail regions. These absorption can be attributed to the creation of excitons localized at doped halogen ions. Effective energies of lattice vibrations related to the central Gaussian part and the exponential tail part are estimated from the measured temperature dependence of half-widths and of Urbach’s tails, respectively. Temperature dependence of these of these bands will be discussed using the Franck-Condon model and modified Urbach’s rule.
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Kikuo Ohi, Susumu Iesaka
1976 Volume 40 Issue 5 Pages
1371-1376
Published: May 15, 1976
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Low-frequency photocurrent oscillation has been found in pure KTaO
3 at low temperature. The oscillation behavior depends on the light intensity and the applied voltage. The temperature of the illuminated surface of KTaO
3 changes synchronously with the oscillation. It is suggested that these effects are caused by the redistribution of electrons over levels under the influence of Joule heat of the photocurrent.
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Yozo Kaifu, Teruo Komatsu
1976 Volume 40 Issue 5 Pages
1377-1382
Published: May 15, 1976
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The optical absorption spectra near the fundamental edge have been measured on high quality single crystals of BiI
3. Above 50 K, the absorption coefficient near the edge is well described by the Urbach’s rule. At lower temperatures, the corresponding transitions are of the allowed indirect type involving the creation of free excitons, and absorption components associated with three phonon energies have been resolved. The energies of the phonons are found to be 2.6±0.1, 7.1±0.2 and 13.4±0.4 meV. The absorption cross-section of the indirect transition is very large compared with that observed in indirect semiconductors and ionic crystals. These results are discussed in view of band nature of BiI
3. Preliminary results on sharp absorption lines near the edge are also given.
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Hideaki Chihara, Akira Inaba
1976 Volume 40 Issue 5 Pages
1383-1390
Published: May 15, 1976
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Heat capacity of NH
4H(ClCH
2COO)
2 and ND
4D(ClCH
2COO)
2 was measured between 3 and 300 K with an adiabatic calorimeter. It showed a lambda-shaped anomaly at 119.7 and 130.3 K for the H and D salts, respectively, with the same entropy of transition of about (
Remark: Graphics omitted.). The isotope effects in chloroacetate anion were extracted by comparing the difference plot of normal heat capacity between two salts with that of NH
4Br and ND
4Br. A collective mode involving the short hydrogen bond in chloroacetate anion is indicated. The unusual behavior below 20 K suggested that the D crystal is harder than the H crystal, and also led to the characteristic properties in these crystals. Two possible mechanisms of phase transition, continuous displacive type and order-disorder type, are examined by the observed heat capacity. Simple and modified order-disorder models are ruled out.
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Kenichi Nanbu
1976 Volume 40 Issue 5 Pages
1391-1396
Published: May 15, 1976
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The problem of the vibrational relaxation of anharmonic oscillators in expansion nozzles has been analysed numerically. It is concluded: (1) Effects of anharmonicity increase with increasing
prr*⁄tanθ and/or
Tr, where
pr and
Tr are the reservoir pressure and temperature, and
r* and θ are the throat radius and expansion angle of the nozzle respectively. (2) Anharmonicity has the effect of somewhat lowering the translational temperature of gas. This effect being taken into account, the relaxation rate of the vibrational energy gets an increase of less than a factor 1.3 due to anharmonicity. Contrary to the Boltzmann distribution of the harmonic oscillators, however, the vibrational distribution function of the anharmonic oscillators undergoes a considerable distortion in the expanding flow.
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Kazuko Kojima, Shigeru Ebata, Akihiko Tamura, Tadanobu Kojima
1976 Volume 40 Issue 5 Pages
1397-1405
Published: May 15, 1976
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A color center, denoted as the
P.
F center, has been found in KCl crystals doped with alkaline earth or rare earth ions, as an intermediate product in the stage of optical
F→
FZ conversion. The
P.
F center is characterized by absorption and emission spectra closely resembling to those of
F centers, but much shorter fluorescence decay-time, 230 ns, as compared with the
F center. It is proposed that the
P.
F center is an
F center perturbed by the electric field of an impurity-complex. Using the data on the
P.
F center, the lifetime of the 2
p→1
s transition for the unperturbed
F center is determined as 50 ns, on the basis of the vibronic model proposed by Ham and Grevsmühl. The experimental data on
F centers can be explained consistently only when the energy difference between the 2s and 2p states are assumed to be about 0.05 eV. The result also suggests that the relaxed excited state of the
F center is more contracted than predicted by Fowler’s large orbit hypothesis.
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Kikuo Ujihara
1976 Volume 40 Issue 5 Pages
1406-1414
Published: May 15, 1976
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In a previous paper we considered the linear problem of a one-dimensional laser having output coupling. In this paper we derive the nonlinear equation for the same model of the laser and solve it for steady state. The output coupling is exactly taken into account and the field is treated as having a continuous spectrum composed of the normal modes of the universe. Damping terms for the atomic polarization and for the population inversion are introduced phenomenologically. The fluctuating forces due to these damping terms and to the initial field are ignored. The resultant field inside the cavity consists of two oppositely travelling waves whose amplitudes are functions of the distance from the coupling surface. Outside the cavity we have a monochromatic, outgoing wave whose amplitude does not change with distance. The threshold inversion and the oscillation frequency are the same as those derived in the linear theory.
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Keiji Moro, Nobuhiko Saitô
1976 Volume 40 Issue 5 Pages
1415-1420
Published: May 15, 1976
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The Brownian motion of a small spherical particle in a general viscoelastic medium is discussed to derive the spectral distribution and the intensity correlation function of the scattered light. A new method is suggested to measure the complex viscosity coefficient of this medium from the light scattering measurements. Simple examples are discussed in detail.
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Naoto Kobayashi, Nobuhiro Maeda, Hiroshi Hori, Masakatsu Sakisaka
1976 Volume 40 Issue 5 Pages
1421-1429
Published: May 15, 1976
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The K Auger electron spectra have been measured for carbon, nitrogen, oxygen, fluorine and neon excited by protons and alpha particles of 0.5–2.6 MeV. In comparison with the spectra obtained by electron impact, the satellite lines have grown more intensively as projectiles become heavier. This indicates the presence of a contribution of simultaneous L shell ionization. A quantitative analysis has been made for the created L vacancies of nitrogen due to N+
p and N+α collisions. The ionization cross sections derived from the Auger yields have been compared with the theories of Born approximation and binary encounter approximation. The deviations from the theories found in O+α, F+α and Ne+α collisions might be explained by a shielding action of L shell electrons against nuclear charge of projectiles.
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Nobuhiro Maeda, Naoto Kobayashi, Hiroshi Hori, Masakatsu Sakisaka
1976 Volume 40 Issue 5 Pages
1430-1436
Published: May 15, 1976
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The L Auger electron spectra have been observed for chlorine and argon bombarded with protons and alpha particles of 0.3–2.6 MeV in energy. The satellite lines, which are attributable to a simultaneous M shell ionization, have increased in comparison with the spectra obtained by electron impact. The numbers of created M shell vacancies of argon are estimated as 0.3±0.1 and 1.1±0.4 in average for protons and alpha particles at 1.8 MeV, respectively. The ionization cross sections for both projectiles have been compared with the theory of binary encounter approximation, resulting in a few tens percent reduction for argon and an overestimation for chlorine. The projectile
z dependence of ionization cross section has been confirmed for chlorine and argon.
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Kunizo Onda
1976 Volume 40 Issue 5 Pages
1437-1445
Published: May 15, 1976
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The validity of the Glauber calculations [Ashihara
et al.: J. Phys. Soc. Japan
38 (1975) 1732)], which have successfully explained the angular distribution for the title process, is investigated by assuming a pure dipole interaction and using an accurate procedure within the framework of the adiabatic approximation. Numerical calculations have been carried out for 4.77 eV electrons scattered by CsCl. It is confirmed that the Glauber approximation gives correct angular distributions in the small-angle region below 50 degrees.
The question for the unsuitableness Born approximation in this subject is answered by using the partial wave analysis of the Born differential cross section and the perturbation expansion of the accurate expression in the adiabatic approximation.
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Toshiaki Ishikawa, Shigetomo Kita, Hokotomo Inouye
1976 Volume 40 Issue 5 Pages
1446-1448
Published: May 15, 1976
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Computation based on the electron gas model for the interaction potentials between closed-shell particles was mode on M
+–Xe (M
+: Li
+, Na
+ and K
+), Rb
+–R and Cs
+–R (R: rare gas atoms). The computation was also extended to some systems composed of open-shell and closed-shell particles, M
+–H, M
+–X and X
+–R (X: C, N and O). The ion-diatom repulsion for M
+–N
2 and M
+–CO obtained on the basis of the dumbbell model with the ion-atom potentials is in good agreement with experimental results.
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Shoichi Hatori, Susumu Shioda
1976 Volume 40 Issue 5 Pages
1449-1455
Published: May 15, 1976
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The constriction of a positive column in a glow discharge which occurs at a high gas pressure (\gtrsim a few Torr) and a large current (\gtrsim 10 mA) is investigated both experimentally and theoretically. The simple extension of the Schottky theory is known to fail in describing the experimental results. It is shown that the constriction is closely connected with the stepwise ionization and the initiation of the gas temperature rise in the constricted core and that it corresponds to the transition of the positive column from the glow to the arc discharge.
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Yoshiaki Arata, Shoji Miyake, Akira Kobayashi, Sadao Takeuchi
1976 Volume 40 Issue 5 Pages
1456-1461
Published: May 15, 1976
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The optimum configuration of the rectangular waveguide type device is given for producing a stable high power microwave plasma. It is shown that helical flow of nitrogen gas stabilizes the plasma beam and contributes to the formation of a virtual “gas wall” between the plasma beam and the pyrex wall. It is clarified that the change in the pyrex tube diameter strongly affects the plasma parameters and the comparison of experimental results with a theory of energy absorption by Meierovich shows a better agreement by assuming the existence of a “gas wall”.
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Toshihisa Honma, Masafumi Kito, Ikuo Kaji
1976 Volume 40 Issue 5 Pages
1462-1468
Published: May 15, 1976
Released on J-STAGE: June 01, 2007
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In the presence of an external gravitational force, high-m quasikink modes of plasma are investigated. The modes become unstable for the mode number
m below a certain critical value. A stability criterion is obtained, which is more stringent than Suydam’s criterion. A dispersion relation for the modes quadratic in ω
2 is also derived. For a constant-pitch field, the growth rates of the modes are calculated and their contour map is presented. It is shown that the stability of the modes does not depend on β=2
P⁄
B2 but
Bθ2⁄
B2 and the maximum growth rates exist only for
k·
B>0.
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Nanigopal Datta, Rabindra Nath Jana
1976 Volume 40 Issue 5 Pages
1469-1474
Published: May 15, 1976
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Hall effects on the hydromagnetic flow past a flat plate in the presence of a uniform transverse magnetic field has been analysed when the free stream oscillates in magnitude only. Solution is obtained for the velocity field for small amplitude oscillations. For small frequency oscillations of the free stream the increase in Hall parameter increases the phase difference of the oscillations of the shearing stress. The resonance frequency of the boundary layer decreases with the increase in Hall parameter.
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Hiroyuki Honji
1976 Volume 40 Issue 5 Pages
1475-1478
Published: May 15, 1976
Released on J-STAGE: June 01, 2007
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Experimental evidence is reported that a two-dimensional vortex is formed in front of a half-submerged circular cylinder, which is supported horizontally near the surface of water in a towing tank and moved in the direction normal to its axis. The experiment was mode at Reynolds numbers (based on the velocity and the radius of the cylinder) less than about 5×10
3. The upstream vortex seems to be due to the forward movement of the surface layer of water driven by the cylinder.
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Kunihito Nagayama, Terutosi Murakami
1976 Volume 40 Issue 5 Pages
1479-1486
Published: May 15, 1976
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A theoretical analysis is made for the behavior of converging shock waves in a concentric two layer system. Finite difference method is used to solve the hydrodynamic equations with numerically convenient constitutive equations proposed. The results show that differences in material properties have appreciable effects on the feature, and that in particular the system having an inner rod of higher shock impedance produces a negative pressure region near the central axis by a converging rarefaction wave.
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Hiroaki Ono
1976 Volume 40 Issue 5 Pages
1487-1497
Published: May 15, 1976
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The modified Korteweg-de Vries equation:
ut+6
u2ux−
uxxx=0,
is solved exactly by means of the ‘inverse scattering method.’
On the basis of this method, an infinite sequence of conserved quantities is obtained.
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Akira Yoshizawa
1976 Volume 40 Issue 5 Pages
1498-1503
Published: May 15, 1976
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The present paper reexamines Edwards’ Fokker-Planck approach for steady homogeneous turbulence, based on turbulent viscosity and turbulent diffusion (S. F. Edwards: J. Fluid Mech.
18 (1964) 239). The energy equation found by Edwards by the use of the probability distribution function is derived using the characteristic function. In dividing the energy equation into the turbulent viscosity and the turbulent diffusion, a disposable function is introduced and made use of so as to eliminate effects of the energy-containing range and the divergence of integrals. This procedure consistently leads to Kolmogoroff’s spectrum:
Ek=1.49
h2⁄3k−5⁄3,
(
h being the rate of energy dissipation and
k the wave number). The numerical coefficient 1.49 is in excellent agreement with the experimental value 1.44 observed by Grant
et al. (H. L. Grant, R. W. Stewart and A. Moilliet: J. Fluid Mech.
12 (1962) 241).
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Shigeaki Suwa, Ken-ichi Kusukawa
1976 Volume 40 Issue 5 Pages
1504-1509
Published: May 15, 1976
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The wind tunnel interference problem in magnetohydrodynamics, in which an inviscid compressible fluid with small electrical conductivity flows steadily past a slender axi-symmetric pointed body of revolution placed in a cylindrical perfectly insulated wind tunnel, in the presence of a crossed magnetic field, is considered. Using the analytical method which was studied by one of the present authors, the streamlines and the space charge in a cross section are calculated.
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Masahiro Agu
1976 Volume 40 Issue 5 Pages
1510-1511
Published: May 15, 1976
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A nonstationary time-series having 1⁄
f spectrum is proposed. The time-series is given by a superposition of the various relaxation processes having random relaxation times and random initial conditions.
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Akira Yokoyama
1976 Volume 40 Issue 5 Pages
1512
Published: May 15, 1976
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Yohtaro Ueno, Takehiko Oguchi
1976 Volume 40 Issue 5 Pages
1513-1514
Published: May 15, 1976
Released on J-STAGE: May 29, 2007
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A new ordered phase, tentatively called “random ordered phase” (ROP) is proposed in the quenched Ising spin system in which ferro- and antiferromagnetic exchange integrals exist. In the ROP each spin points to the same direction as the molecular field which is either up or down and is altered from site to site according as the various situations of surroundings. The phase transition is characterized by “random magnetization” and “random susceptibility”, whose expressions are given.
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Masaru Tsukada
1976 Volume 40 Issue 5 Pages
1515-1516
Published: May 15, 1976
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Properties of the Wigner lattice in the two-dimensional electron system under strong magnetic field is investigated. Especially the phonon dispersion relation and the melting curve is calculated by the self-consistent harmonic approximation. It is found that the impurity potential is important to explain the width of gaps in the curve of σ
xx vs gate voltage found is Si–MOS structures.
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Miki Wadati
1976 Volume 40 Issue 5 Pages
1517-1518
Published: May 15, 1976
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An explicit transformation relating solutions of an exponential lattice equation and a nonlinear self-dual network equation is presented. Using the transformation, fundamental equations of inverse scattering method for an exponential lattice is obtained. This transformation is considered to be a discrete version of Miura transformation.
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Yuzo Hashimoto, Hironobu Fujii, Tetsuhiko Okamoto
1976 Volume 40 Issue 5 Pages
1519-1520
Published: May 15, 1976
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The magnetization and susceptibility were measured for TbCu
2 and DyCu
2 single crystals from 4.2 K to room temperature. The magnetization process at 4.2 K showed a spin-flip transition and a two step one for TbCu
2 and DyCu
2, respectively. The paramagnetic Curie temperatures along the principal axes showed large anisotropy for both compounds, from which the crystalline field parameters of orthorhombic symmetry
V20 and
V22 were estimated.
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Yoshio Kitaoka, Kunisuke Asayama
1976 Volume 40 Issue 5 Pages
1521-1522
Published: May 15, 1976
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New NMR signals of Mn
55 were observed in Ni
100−xMn
x and Ni
100−xFe
x : Mn alloys in the frequency ranges of 140∼180 MHz and 100∼150 MHz, respectively. These signals are attributed to the Mn atoms that are coupled antiferromagnetically to the host magnetization.
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Shin Tsunekawa, Humihiko Takei
1976 Volume 40 Issue 5 Pages
1523-1524
Published: May 15, 1976
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Ferroelastic domain switching behaviour is observed in large and high quality LaNbO
4 and NdNbO
4 single crystals grown by the Czochralski method. The domain walls which are (10\bar2) and (201) twin planes move when a small stress is applied, and return to the initial positions when the stress is removed. This
back-
switching behaviour is much influenced by a strain rate: the perfect back-switching is not expected by decreasing the strain rate. This behaviour may be explained by assuming a restoring force due to the restricted rotation of NbO
4 tetrahedra in the distorted Scheelite-structure.
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