-
Masatoshi Nakayama
1975 Volume 39 Issue 2 Pages
265-274
Published: August 15, 1975
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Various phenomena related to the electromagnetic response of solid surface are expressed in terms of the surface admittance for S- and P-polarization in a way independent of model. Formulas are given for optical reflection, dispersion relation of surface wave, image force, energy loss of specularly reflected electrons, and dispersion force between solid bodies. A scheme to calculate the contribution of the surface admittance is presented by self-consistent field approach. Besides the fully self-consistent expression, perturbation formulas are given. The slowly varying field limit is investigated. Two dimensional model and layer model are discussed.
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Kazuo Hattori
1975 Volume 39 Issue 2 Pages
275-278
Published: August 15, 1975
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Ground-state energy of a polaron in the strong-coupling region is calculated. Variational method and second-order perturbation theory are used to improve the usual strong-coupling theory. The results obtained are compared with those by the Feynman theory.
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Tsuneya Ando, Yukio Matsumoto, Yasutada Uemura
1975 Volume 39 Issue 2 Pages
279-288
Published: August 15, 1975
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Hall conductivity σ
XY is studied in various approximations. Characteristics of σ
XY are obtained for the case of both short- and long-ranged scatterers in the self-consistent Born approximation, which is the simplest one free form the difficulty of divergence. In case of short-ranged scatterers, a relation is shown to hold between σ
XY and σ
XX within this approximation, if one uses a relaxation time under magnetic fields. Under strong magnetic fields, effects of higher Born scattering become important in low-lying Landau levels. They depend on the sign of scatterers and strongly on their concentrations. Effects of simultaneous scattering from many scatterers are calculated to the lowest order.
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Junji Mada, Kazushige Nomura, Shuichi Iida
1975 Volume 39 Issue 2 Pages
289-291
Published: August 15, 1975
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Heat treatment relaxation of the growth-induced uniaxial anisotropy of the mixed garnet (Eu
2.2 Gd
0.8 Al
0.6 Fe
4.4 O
12) was investigated by means of annealing the specimen at high temperature in various atmospheres. The relaxation of the anisotropy constant of this garnet consists of two processes. At 1000°C, these relaxation times are 12 minutes and 35.0 hours for the two processes, respectively. It is supposed that the diffusion of rare earth ions is mediated by the oxygen vacancies.
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Gentaro Kaji, Akira Tasaki, Kiiti Siratori
1975 Volume 39 Issue 2 Pages
292-294
Published: August 15, 1975
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Induced magnetic anisotropy constant (
Ku) of Li
0.5Fe
2.5−xMn
xO
4 poly-crystals (0≤
x≤0.4) was measured at room temperature.
x dependence of
Ku shows an abrupt change at
x=0.3. When
x>0.3,
Ku increases more rapidly than the range of
x<0.3. These properties are discussed based on the Jahn-Teller effect of Mn
3+ ions.
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Shoichi Tomiyoshi, Hiroshi Watanabe
1975 Volume 39 Issue 2 Pages
295-302
Published: August 15, 1975
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The magnetic structure of Mn
3Si (bcc Fe
3Al type crystal structure) at low temperatures has been determined by neutron diffraction using single crystal samples. It is found that Mn
3Si has a helical spin structure (Néel temperature 25.8 K) with a wave vector
q parallel to one of 〈111〉 directions and of magnitude 0.85·1⁄2·2π
K111, which is near the boundary of the Brillouin zone. The magnetic structure is either a proper screw or a transversal sinusoidal structure and the magnetic moments at the two Mn sites are μ
MnI=1.72 μ
B and μ
MnII=0.19 μ
B. The temperature dependence of the magnitude of the wave vector
q is similar to that of Cr. From these data the possibility of an itinerant electron antiferromagnetism of Mn
3Si is suggested in comparison with the SDW in Cr.
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Shigeru Tsunashima, Toshitaka Fujii, Susumu Uchiyama
1975 Volume 39 Issue 2 Pages
303-311
Published: August 15, 1975
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The kinetics of the relaxation process of the M-induced uniaxial magnetic anisotropy of the ferromagnetic binary alloy with the cubic structure was theoretically studied. The interaction energy of the closest pair of the
X- and
Y-atom is assumed to be written in the form of
EXY=
UXY+
LXY(cos
2α−(1⁄3)), where α is the angle between the bond direction of the atom pair and the direction of the magnetization. The first term is independent of α, and the second term is the pseudodipolar interaction term. The rate equation for the directional pair probability of the interacting atoms is obtained. According to this equation, the equilibrium value of the anisotropy energy is the same with Néel’s formula, and the relaxation behavior of the anisotropy depends on the crystal structure.
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Osamu Okada, Tomonao Miyadai, Syun-iti Akimoto
1975 Volume 39 Issue 2 Pages
312-316
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An ESR spectrum of Mn
2+ with a strong axial crystal field was observed in powder sample of pyrite phase ZnS
2. The parameters obtained at 4.2 K are;
g=2.009±0.004,
D=(+)0.151±0.001 cm
−1,
F=(−)0.003±0.001 cm
−1, |
E|≤0.001 cm
−1 and
A=(−)0.0071 cm
−1.
D and
F are uniaxial field parameters of the first and the second order, respectively.
E is a rhombic field and
A is a hyperfine constant, the sign of which was assumed as negative.
D decreases slightly with increasing temperature (
D=(+)0.142 cm
−1 at room temperature).
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Toshiaki Enoki, Ikuji Tsujikawa
1975 Volume 39 Issue 2 Pages
317-323
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Magnetic behaviours of the mixed crystal, Ni
pMg
(1−p)(OH)
2, as a randomly diluted magnet of the quasi-two dimensional antiferromagnet, Ni(OH)
2, were investigated by measurements of the susceptibility and the magnetization. In pure Ni(OH)
2, the three kinds of exchange interactions were estimated as follows:
J1⁄
k∼2.70 K,
J2⁄
k∼−0.28 K and
J3⁄
k∼−0.09 K. The anisotropy energy mainly comes form the crystalline anisotropy. In Ni
pMg
(1−p)(OH)
2 the paramagnetic susceptibilities obeyed the Curie-Weiss law well above the critical temperature,
TN(
p), for the concentration, 0.4\lesssim
p≤1. Below
p∼0.4, the susceptibilities obeyed the Curie-Weiss law, but with the different Curie and the Weiss constants in the lower and higher temperature regions. This may result from ferromagnetic short range order in the lower temperature region.
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Toshiaki Enoki, Ikuji Tsujikawa
1975 Volume 39 Issue 2 Pages
324-331
Published: August 15, 1975
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The magnetic phase transition of the mixed crystals of nickel and magnesium hydroxides, Ni
pMg
(1−p)(OH)
2, as randomly diluted magnets was investigated by measurements of the susceptibilities. The critical curve (phase transition temperatures versus concentrations,
p) shows a terraced form in the concentration region below
p∼0.4, which might reflect the quasi-two dimensionality of Ni(OH)
2. The critical concentration,
pc, is estimated as about 0.1. Furthermore, the dilution of Ni(OH)
2 by Mg(OH)
2 changes the values of θ⁄
T°
max and χ
M°(
T=0)⁄χ
M°
max, and the shape of the peak of the susceptibility, where
T°
max is the temperature at which the susceptibility, χ
M° , has a peak value, χ
M°
max. These changes are interpreted as a result of the change of the spin arrangement in an ordered state depending on the concentration,
p.
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Susumu Ikeda, Yoshikazu Ishikawa
1975 Volume 39 Issue 2 Pages
332-339
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Critical phenomena of various physical properties such as sublattice magnetization (〈
SQz〉), static susceptibility χ(0), specific heat (
Cm), electrical resistivity (ρ
m) and thermo-electric power (
S) of γ FeMn alloys have been measured for three different specimens with composition close to Fe
0.5Mn
0.5. It has been found that the maxima of
Cm, dρ⁄d
T and dχ(0)⁄d
T occurs about 9 degrees below the Néel temperature
TN where (〈
SQz〉) disappears and the longitudinal staggered susceptibility (χ
⁄⁄(
Q)) diverges and χ(0) gives the maximum. ρ and
S also show an anomaly at
TN. Such a curious phenomenon has been understood if we assume that the Néel temperature is distributed in the sample with the standard deviation of 5 degrees and with the maximum cut off of 495 K.
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Takashi Tsuchida, Shojiro Sugaki, Yoji Nakamura
1975 Volume 39 Issue 2 Pages
340-343
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The magnetic properties of GdCo
2 and Gd
1−xY
xCo
2 have been observed and discussed in terms of the molecular field approximation. An appropriate set of interaction parameters reproduces the temperature dependence of the magnetization of GdCo
2 and the concentration dependence of the Curie temperature of Gd
1−xY
xCo
2 for
x<0.2. Among the three kinds of interaction, the interaction between Gd and Co atoms plays the most important role in determining the Curie temperature. A negative deviation of the Curie temperature form the molecular field estimation, observed for
x>0.2, suggests that the Co moment is suppressed by Y substitution and quite sensitive to magnetic environments. A stepwise anomaly in the temperature dependence of the magnetization previously reported could not be observed.
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Jiro Yamashita, Shinya Wakoh, Setsuro Asano
1975 Volume 39 Issue 2 Pages
344-351
Published: August 15, 1975
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The electron-phonon interaction and the electron-magnon interaction in ferromagnetic nickel below room temperature are investigated by a realistic model. The Fermi vectors, the Fermi velocities and the wave functions are determined by the APW method. The phonon spectrum is calculated by the Born-von Karman model. The matrix elements of the electron-phonon interaction are evaluated by the single site approximation, which was applied to Mo with success. On the other hand, the matrix elements of the electron-magnon interaction are derived by a simple phenomenological model. The theoretical result on the electrical resistivity due to the electron-phonon interaction is found to be in reasonable agreement with experiment. The theoretical value of the electron-phonon mass enhancement factor is also reasonable. The electron-magnon interaction does not seem to make an important contribution to the resistivity of nickel below room temperature.
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Shinji Wada, Kunisuke Asayama
1975 Volume 39 Issue 2 Pages
352-355
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The nuclear spin-lattice relaxation time,
T1, and spin-echo phase-memory time of V
51 and Co
59, and the Knight shift of Co
59 in VCo alloy have been studied at liquid He
4 temperatures in Co concentration from 0.2 to 6.0 at %. A positive Knight shift of Co
59, 1.57±0.05(%), is indicative of a dominant orbital hyperfine interaction. With increasing Co concentration,
T1T of V
51 increases gradually.
T1T of Co
59 is larger than that of V
51 in 0.2 at % Co alloy and decreases rapidly with Co concentration. It is concluded that the density of states at the Fermi level at Co site is smaller than that of the host element and increases with Co concentration in contrast to the decrease of the bulk density of states. The spin-echo phase-memory decays of Co
59 and V
51 are found to correspond to a nearly Gaussian and a Lorentzian line shape, respectively.
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Kiyoyuki Terakura, Ikuko Terakura
1975 Volume 39 Issue 2 Pages
356-363
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The effects of a surface on the electronic structure of the d band of Ni and Fe are investigated with a tight-binding model for thin films. It is shown how the local density of states for the surface, ρ
s(
E), changes as the thickness of the film increases and that a thin film with a thickness of 5 to 7 layers can be used as a model of semi-infinite crystal for the investigation of the electronic structure near the surface. The local density of states for surface is different considerably from that of the bulk in each case of the (001), (110) and (111) planes. Especially, there is a fairly sharp peak in the case of the (001) plane of Ni which results from surface states. Detailed discussions are given on these surface states.
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E-Ni Foo, How-sen Wong
1975 Volume 39 Issue 2 Pages
364-366
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Kalkstein and Soven’s Green’s function theory for semi-infinite crystal is generalized for the case of thin film or finite linear chain.
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Makoto Okochi
1975 Volume 39 Issue 2 Pages
367-374
Published: August 15, 1975
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The non-relativistic augmented plane wave method has been used to determine the electronic energy bands, density of states, and Fermi surface of FeAl ordered alloy having the CsCl-type structure. The results agree quite well with experimental results on electronic specific heat, Knight shift, thermoelectric power, and Hall effect. The Fermi surface is found to be considerably different from those of β′NiAl and β′CuZn, owing to the relative position of the
d band. The valley and peak right above the Fermi level on the density-of-states curve is found to originate from the hybridization between the
p band and the
d band. The alloy phase stability is discussed considering this fact.
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A. K. Agarwal
1975 Volume 39 Issue 2 Pages
375-382
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In this paper the phenomenon of frequency mixing of acoustic waves in semi-conductors as a result of electron-phonon interaction through a strain dependent dielectric constant (SDDC) has been analytically investigated. The dependence of subharmonic generation on account of electron-phonon interaction due to SDDC on the various parameters i.e. ω, β, γ, etc., displays marked differences with that due to piezoelectric interaction, studied earlier by Conwell, Ganguly and Spectror. Numerical results have been presented for the typical case of a BaTiO
3 sample. It is found that for such materials (with large dielectric constants) the electron-phonon interaction effects due to SDDC are much more important than piezoelectric interaction in determining the sub-harmonic genera- tion.
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Koichi Matsuura, Ichiro Tsurumi
1975 Volume 39 Issue 2 Pages
383-389
Published: August 15, 1975
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Photoluminescence spectra, glow curves of blue and green emissions and the thermal bleaching of the 2.3eV absorption band (due to a single-negatively charged sulfur vacancy) have been measured on ZnS crystals heated in sulfur or zinc vapor. It has been found that the as-grown specimens show the self-activated blue emission (470 nm) and a weak green emission. The specimens heated in zinc or sulfur vapor show mainly the copper blue (452 nm) and the copper green (545 nm) emissions. The temperatures of glow peak maxima are obtained as 133,165,207 and 235K with a heating speed of 1 deg·sec
−1. The emission of the 133 K glow peak consists of the copper blue emission and the others of the self-activated blue or the copper green emission. The 2.3 eV band is bleached thermally accompanied by the 133K glow emission. It is concluded that the 133 K glow peak is due to positive holes released from hole trapping centers while the others due to electrons from electron trapping centers.
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Hitoshi Nishimura, Masao Tomura
1975 Volume 39 Issue 2 Pages
390-397
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Under the excitations in the fundamental absorption bands, luminescence and excitation spectra for doped impurities as well as a self trapped exciton in a KI crystal are studied in detail at a temperature range of 5∼100 K. In doped crystals, impurity luminescences are induced instead of the intrinsic luminescence at 3.01 eV which comes from the self trapped exciton under the excitation in the first exciton absorption band. The induced impurity luminescence are confirmed to be due to collision of free excitons with doped impurities. The diffusion coefficient of the free exciton is found to be proportional to
T−1⁄2 below 40 K and above that temperature to
T1⁄2[exp(hω⁄
kT)−1]. The value of the diffusion coefficient is estimated to be about 0.1 cm
2 sec
−1 at 5 K.
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G. Guillot, A. Nouailhat, P. Pinard
1975 Volume 39 Issue 2 Pages
398-402
Published: August 15, 1975
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We have measured the
F center production efficiency in KBr between 80 K and 220 K from kinetics of disappearing
F2 centers and creation kinetics of
HA(Li). This efficiency increases following an Arrhenius law with an activation energy of about 0.025 eV. We discuss the apparent agreement between the energy activation value obtained by these experiments and the one obtained from pulse irradiations. The increase of the creation yield can be understood with the recently proposed Toyozawa’s model for
F-
H pair formation.
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Kunio Fujiwara, Toshio Hyodo, Yasuo Takakusa, Osamu Sueoka
1975 Volume 39 Issue 2 Pages
403-410
Published: August 15, 1975
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The momentum distribution of annihilation photon pairs in LiF observed at 293 K was found to be slightly broader than that at 89 K. Assuming that the positrons are thermalized and annihilate mainly in the polaron states, the broadening was analyzed in terms of their effective mass. The positron polarons are very likely to have a mass considerably larger than those of the electron polarons. This result is consistent with the consequence of a band-mass calculation made in the present work.
Irradiation effects due to the positron source on the angular correlation, i.e. a gradual increase in the peak height at 293 K and a decrease at 89 K, were also detected and attributed to the irradiation-induced changes in the density of positron traps. Holes play an important role in the decrease at 89 K.
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Tsuneya Ando
1975 Volume 39 Issue 2 Pages
411-417
Published: August 15, 1975
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The electronic structure of subbands in an
n-channel accumulation layer on a Si (100) surface is studied in the Hartree self-consistent approximation. An image potential arising form the existence of an interface between the semiconductor and its oxide is taken into account. It reduces subband-splittings especially at high concentrations of surface electrons. Effects of strong magnetic fields applied parallel to the surface are investigated. The electronic structure becomes a mixture of the electric subbands and the magnetic fields applied parallel to the surface are investigated. The electronic structure becomes a mixture of the electric subbands and the magnetic surface states. Optical spectra due to intersubband transitions are calculated. The absolute value of the theoretical peak energy is much smaller than the experiment of Kamgar
et al., but its shift caused by magnetic fields is in reasonable agreement with their experiment.
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Minoru Itoh, Yoshio Nakai
1975 Volume 39 Issue 2 Pages
418-426
Published: August 15, 1975
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Temperature dependence of the emission intensities for two emission bands due to isolated and paired halogen impurity ions in KBr:I and NaCl:Br has been investigated in the region from 10 to 400 K for various energies of the exciting light. Under excitation at the exciton absorption band, the emission intensities decrease as ∼
T−1⁄2. This suggests that energy transfer by excitonic mechanism is most likely to occur in these systems. Under excitation at the interband transition region, the emission intensities are found to be enhanced by the migration of mobile
VK-centers to halogen impurities.
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Takehiro Takoshima, Itaru Tatsuzaki
1975 Volume 39 Issue 2 Pages
427-434
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Precise angular and temperature dependences of NMR 1⁄2↔−1⁄2 linewidth of the
75As in KH
2AsO
4 have been investigated in the para-electric phase for both the
a and
c-axes rotations. The temperature of sample was regulated within ∼0.1°C near the phase transition temperature as well as in time and space. The angular and temperature dependences of an anomalous broadening are well explained by the adiabatic broadening calculated on the basis of an order-disorder model. It is shown that the anomalous broadening depends on temperature as log(
T−
Tc) if the depolarization field owing to the long range dipole-dipole interaction is taken into account. This temperature dependence is in accord with the experimental result from about −100°C to 2∼3°C above
Tc.
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Hikaru Terauchi, Hisataka Takenaka, Kohji Shimaoka
1975 Volume 39 Issue 2 Pages
435-439
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X-ray scattering from K
2SeO
4 crystal at temperatures near
Tm=129.5 K is measured to elucidate the nature of the mechanism of the structural phase transition. On approaching
Tm the super-lattice reflection at (2/3, 0, 4) decreases slowly, indicating that the transition at
Tm is of the second order. The diffuse intensity near (2/3, 0, 4) increases near
Tm and its distribution shows a strong anisotropy elongating along the
a*-direction. It is suggested that the transverse optical phonon polarized along the
c-direction softens at
q=(2π⁄3
a, 0, 0) near
Tm.
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Yasunari Takagi, Takeshi Shigenari
1975 Volume 39 Issue 2 Pages
440-447
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Low frequency
E(
x,
y)-mode Raman spectrum of a KH
2PO
4 crystal is discussed in terms of the pseudo-spin model extended by Havlin
et al. to the problem of transverse susceptibility. Temperature dependence of the susceptibility obtained from the integrated intensity of a broad continuum of the Raman spectrum can be well interpreted by their theory. The theory indicates that this mode, just like the
B2(
z)-soft phonon mode, originates from a zone-center phonon corresponding to a collective proton motion in the
a-
b plane. Dynamics of the
E-mode is also discussed in the framework of the pseudo-spin formalism and it is shown that this model is applicable not only to
B2(
z) soft mode but also, at least qualitatively, to the
E(
x,
y) mode in spite of the apparently different behaviour of the two modes with respest to the phase transition.
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Hiroyasu Shimizu, Yoshikazu Ohbayashi, Keiichi Yamamoto, Kenji Abe, Mi ...
1975 Volume 39 Issue 2 Pages
448-450
Published: August 15, 1975
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Far-infrared reflectivity measurements have been made at room temperature for CsCl single crystals obtained by the melt-growth under high pressure. The reflection spectra have been analyzed using Kramers-Kronig relation and the classical two oscillator model, and optical constants (n, k) are calculated. The sideband structure has been clearly observed near 140cm
−1, which is discussed by considering the relaxation of the resonant TO phonon anharmonically coupled with two other phonons.
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Anibal J. Camnasio, J. A. Gonzalo
1975 Volume 39 Issue 2 Pages
451-459
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A Comparative study has been made of the specific heat in single crystals of triglycine sulfate (TGS) and deuterated triglycine sulfate (DTGS). Measurements were performed (a) in the temperature interval 100–400 K, and (b) around the respective critical regions (at small temperature intervals ∼0.02°C). In the low temperature region, both experimental curves were almost coincident, and they showed a temperature dependence indicative of strong anomalous anharmonicity. The heats of transition (
ΔQ=1.90±0.10 joule/g.) and entropy change (
ΔS=(6.21±0.30)×10
−3 joule/g°C) were almost the same for both crystals. The specific heat discontinuity was substantially different in both cases,
ΔCp=0.24±0.03 joule/g°C for TGS, and
ΔCp=0.48±0.03 joule/g°C for DTGS. Calculations based on both the thermodynamic theory and the statistical theory of ferroelectrics show fair agreement with the data.
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Kazuharu Toyokawa, Hidenobu Hori, Osamu Wakishima, Muneyuki Date
1975 Volume 39 Issue 2 Pages
460-466
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Electron bubble current in liquid helium II under a strong pulsed electric field was investigated and a new oscillation phenomenon was found. The frequency was about 0.2∼2 kHz in usual experimental conditions and it depends strongly on temperature and field strength. There is a critical field below which no oscillation is found. A theoretical analysis shows that the phenomenon can be attributed to the space charge bunching effect induced by the field dependent mobility of electron bubble. The mechanism is, to some extent, similar to the Gunn effect in semiconductors such as n-type GaAs.
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Akinori Inoue
1975 Volume 39 Issue 2 Pages
467-470
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The fluorescence peak intensity of anthracene crystals was measured as a function of the incident light intensity, using a pulsed nitrogen laser as an excitation source. Non-linear quenching of fluorescene was observed at higher excitation intensities. The phenomena are interpreted in terms of the bimolecular annihilation of singlet excitons, which takes place much faster than the present detecting system. From the exciton density at the threshold of these phenomena, the upper limit of the collision distance for the singlet exciton was determined to be 40Å. The value obtained is consistent with the dipole mechanism suggested for the collision annihilation of excitons.
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Seishi Kikuta, Ikuo Ishikawa, Kazutake Kohra, Sadao Hoshino
1975 Volume 39 Issue 2 Pages
471-478
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Dynamical diffraction phenomena of neutrons are studied with a highly parallel exploring beam which is obtained by selecting the central part of the wave fan. The 111 reflection of silicon single crystals is used with neutron wavelengths of 0.86Å and 1.50Å. (i) The rocking curve of the Bragg-case diffraction which is very close to the intrinsic diffraction curve of silk hat type with the reflection per cent of about 100% is measured with the double-crystal arrangement of parallel setting. The angular spread of the exploring beam, 0.065″, is used, which is 1/8.5 times the half-value width of the intrinsic curve. (ii) The minute deviation angle of the beam, 0.032″, refracted by a wedge-shaped germanium crystal is measured with the double-crystal arrangement of parallel setting, where the deviation angle is magnified to 59′ in the wave fan of the second crystal. (iii) By using a neutron interferometer the change in the optical path due to a wedge-shaped material inserted is measured.
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Gen Inoue, Soji Tsuchiya
1975 Volume 39 Issue 2 Pages
479-486
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The 4.3μm fluorescence from CO
2(00
01) induced by the pulsed irradiation of the HBr laser line of P
−2 (6) transition has been measured in the CO
2–N
2 and CO
2–CO mixtures at 300∼150K. The analysis based on the mechanism including the inter- and intra-molecular vibration-to-vibration (V–V) energy transfers of CO
2(00
01) gives the rates for respective processes. The observed V–V rate between CO
2(00
01) and N
2 shows a negative temperature dependence, and agrees with a simple extrapolation of the data at higher temperatures as well as the calculation by the Sharma-Brau theory. Contrary to this, the intermolecular V–V rate between CO
2(00
01) and CO attains a minimum at a temperature around 300K. The intramolecular V–V rate could be determined only for the mixture of CO
2 and N
2; the temperature dependence of the rate was reduced at lower temperatures and this was a phenomenon common to the CO
2(00
01) deactivation in inert monoatomic gases.
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Hideo Kozima
1975 Volume 39 Issue 2 Pages
487-491
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In a hot cathode d.c. discharge tube with mercury vapor, the rf electric field with a frequency up to 2 MHz was applied between an anode and a cathode in a static axial magnetic field. The electron temperature measured by a Langmuir probe and the ion temperature by an energy analyzer are studied as functions of the applied rf and static field parameters. The measured ion temperature markedly increased at several frequencies of the applied field. At the same time, the parametric excitation of oscillations in the plasma was observed by using a panoramic spectrum analyzer. There were excited oscillations with the same frequencies as that of the rf field which increased ion temperature. These effects are investigated by varying the ion density and the magnetic field strength. The results are consistent with an interpretation that one of the excited oscillations is the lower hybrid oscillation and it decays to heat the plasma.
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Takashi Ikuta
1975 Volume 39 Issue 2 Pages
492-500
Published: August 15, 1975
Released on J-STAGE: June 01, 2007
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The general theory of a magnetohydrodynamic parallel-transverse flow is studied in the relativistic case as well as in the non-relativistic case and is applied to the axisymmetric motion of a plasma flowing out of a rotating magnetized conductor. By solving the ideal, steady, magnetohydrodynamic equations, an asymptotic solution at large radial distance is obtained, which shows that in the poloidal projection the flow and the magnetic field are aligned but the main flow is radial while the dominant component of the magnetic field is toroidal.
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Takeyasu Kotera, Katuro Sawada
1975 Volume 39 Issue 2 Pages
501-508
Published: August 15, 1975
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Classes of non-linear partial differential equation solvable by the inverse scattering methods related to the Schrödinger operator and the generalized Zakharov-Shabat operator are presented. Derivations and classification of partial differential equations are different from P. D. Lax’s (Commun. pure appl. Math.
21 (1968) 467) and M. J. Ablowitz
et al’s (Phys. Rev. Letters
31 (1973) 125). It is shown that the equations of each class can be derived by a simple successive procedure.
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Akira Yoshizawa
1975 Volume 39 Issue 2 Pages
509-512
Published: August 15, 1975
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This paper is concerned with a mechanism of the movement of a separation point on a body immersed in a viscous fluid. Unsteady motions of the body or the fluid may be considered to play an essential role in its mechanism. This paper investigates the case of a decelerating motion of the surrounding fluid, which induces an adverse pressure gradient on the body. A local solution of the unsteady boundary-layer equation is constructed near the separation point. A close examination of the skin friction shows the possibility of its movement.
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Syozo Kubo
1975 Volume 39 Issue 2 Pages
513-518
Published: August 15, 1975
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The radiative heat transfer from a line heat source in a uniform flow of an inviscid, non-heat-conducting, gray and optically thick gas is analyzed by the method of matched asymptotic expansions. The radiation field is considered in LTE. The case is considered in which Mach number is small and the intensity of the heat source is weak. Thus the analysis is based on the linearized equations. The line heat source is considered as a limit of a black circular cylinder whose radius tends to zero and whose temperature tends to infinity in order to give a finite effect to the radiation field. The solution is studied in detail in the radiation region, which is the nearly axisymmetric region whose distance from the heat source is of order of the photon mean free path. Numerical discussion is also made of the temperature distribution in the region.
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Tosio Miyagi, Kazuhiro Nakahasi
1975 Volume 39 Issue 2 Pages
519-526
Published: August 15, 1975
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This paper deals theoretically with the two-dimensional flow driven by a circular cylinder which performs unharmonically translational oscillation in an unbounded viscous incompressible fluid otherwise at rest. Slow steady secondary flow occurs outside the oscillatory boundary layer around the cylinder, provided that the non-dimensional amplitude of the oscillation ε and the boundary layer thickness are both extremely small. It is found that induced steady flow of O(ε) is symmetric with respect to the direction of the oscillation and vanishes at infinity; however, in O(ε
2) asymmetric steady streaming is induced in the main field and remains at infinity as a uniform flow in the direction of oscillation, due to the effect of the asymmetry in the motion of the circular cylinder.
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Kotaro Onizuka
1975 Volume 39 Issue 2 Pages
527-535
Published: August 15, 1975
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A site percolation model of 50×50×50 sites is examined by computer to treat the generalized conductivity characteristic of a two-phase material with random structure (porous material). An enumeration of clusters of one phase (pores) in the model provides cluster-size distribution, percolation probability
P(
p) and an estimate of the critical probability 0.31<
pc<0.32 for the site percolation problem in a simple cubic lattice. A direct calculation of the bulk electrical conductivity of the 3D random resistor network derived from the model reveals a special relation between the conductivity
k and the concentration
p of the one phase (porosity
p of the model):
k=Const. (
p−
pc)
1.725±0.005 in which
pc=0.318±0.002. The above power law indicates a critical nature of the phenomenon.
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S. M. Shan, K. Das Gupta
1975 Volume 39 Issue 2 Pages
536
Published: August 15, 1975
Released on J-STAGE: May 29, 2007
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Yoshiro Irie, Mikio Hyakutake, Masaru Matoba, Masateru Sonoda
1975 Volume 39 Issue 2 Pages
537-538
Published: August 15, 1975
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Angular distributions of neutrons from pre-compound decay are resolved from those of compound-nucleus process for the
93Nb (
n,
n′) reaction induced by 14 MeV neutrons. Comparisons are made with the calculated results and good agreements are obtained.
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Kenji Shimizu, Naokatsu Sano, Junkichi Itoh
1975 Volume 39 Issue 2 Pages
539-540
Published: August 15, 1975
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The NMR of Lu
175 in ferromagnetic Lu(2%)–Tb and Lu(2%)–Dy alloys was investigated at 1.4 K. Assuming the asymmetry factors calculated by Holden
et al. which are 0.32 and 0.35 for Tb and Dy respectively, the experimental results are analysed. The effective fields at the Lu nuclei are found to be 302 kG (Tb alloy) and 239 kG (Dy alloy). The principal values of the electric field gradients along the
c-axis are 1.91×10
24cm
−3 (Tb alloy) and 1.92×10
24cm
−3 (Dy alloy). The conduction electron contribution to the electric field gradient is about 70% of that produced by the lattice charges.
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Kazushi Yamauchi, Tadashi Mizoguchi
1975 Volume 39 Issue 2 Pages
541-542
Published: August 15, 1975
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The reduction of magnetic moments of 3d transition metal atom in amorphous metal-metalloid alloys is simply interpreted by means of the electron transfer from metalloid atoms to the hole of 3d metal atoms.
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Ken-ichi Kumagai, Kunisuke Asayama
1975 Volume 39 Issue 2 Pages
543-544
Published: August 15, 1975
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NMR of Gd in ferromagnetic (Ce
1−xGd
x)Ru
2 was observed in a region of
x≥0.105. The internal field at Gd is −180±10 kOe. The transverse relaxation time depends on
x, temperature and external field. Sharp superconducting transition was confirmed for
x≤0.105 by ac susceptibility measurement. The intensity of the signal in alloy of
x=0.105 at 1.2 K first increases and then decreases with external field, which indicates that the signal comes from superconductor. The results are compatible with the previous results which support the coexistence of superconductivity and ferromagnetism.
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Kenji Hinode, Shoichiro Tanigawa, Masao Doyama
1975 Volume 39 Issue 2 Pages
545-546
Published: August 15, 1975
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Positron lifetime spectra were measured for Cu specimens with different concentrations of lattice defects. After subtracting the source components, lifetime spectra were successfully resolved into two components. Obtained results were quite consistent with those expected from the trapping model. The positron trapping mechanism from free to trapped states was especially checked in terms of the variance of the shorter lifetime component. Deduced values for τ
c (lifetime of untrapped positrons) and τ
t (lifetime of trapped positrons) were 125±5 psec and 189±10 psec, respectively.
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Hiroshi Ohkura, Masao Matsuoka, Yuzo Mori
1975 Volume 39 Issue 2 Pages
547-548
Published: August 15, 1975
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The spin-lattice relaxation time of the
FA(Li) centers in KBr shows a remarkable temperature dependence with a distinguished isotope effect. It is found that the Murphy’s relaxation mechanism is the most suitable to explain these characteristics. Tunneling probability, W
0, and tunneling splitting,
Δ, are determined to be as 1.0×10
3 and 0.5×10
3 sec
−1, and 6.7 and 3.9 K, for the
FA(Li
6) and
FA(Li
7) centers, respectively.
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Yamichi Ohmura
1975 Volume 39 Issue 2 Pages
549-550
Published: August 15, 1975
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Weak field magentoresistance anisotropies near room temperature were observed on n-type (001) Si on sapphire. They are M
〈100〉〈001〉<M
〈100〉〈010〉, M
〈100〉〈100〉∼0 and M
〈110〉〈110〉>M
〈110〉〈001〉>M
〈110〉〈\bar110〉, where the superscript and subscript denote the magnetic field and the electric current directions, respectively. These anisotropies are well explained when it is assumed that the 〈001〉 energy ellipsoids make little contribution to conduction, the energy being raised relative to the 〈100〉 and 〈010〉 ellipsoids due to the large lateral strain induced by the thermal expansion coefficient difference.
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Masahiro Kimura, Tadashi Nishitani
1975 Volume 39 Issue 2 Pages
551-552
Published: August 15, 1975
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Helium ion impact on H
2O exhibits quite a different spectrum from that electron-impact on H
2O gives. In the former, the OH
+ A,
3Π→
X,
3Σ− band-system can be observed in addition to the OH
A,
2Σ+→
X,
2Π. On the contrary, there is no trace of the OH
+ bands in the latter. These experimental evidences have been obtained by the crossed-beam technique.
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Muneyuki Date, Hidenobu Hori, Kazuharu Toyokawa, Osamu Wakishima, Osam ...
1975 Volume 39 Issue 2 Pages
553-554
Published: August 15, 1975
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A crossover effect between the dispersion curves of a charged vortex ring and an ion in liquid helium II is proposed with the hydrodynamic models of two intermediate states. This effect can satisfactorily explain various properties such as the field and pressure dependences of ion motions already reported by many researchers. The coupling energy
Δ was estimated as 25 and 40 K for the positive and negative ions, respectively.
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