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Kouhei Harada, Shigehide Kuhara, Kazuyoshi Hirakawa
1981 Volume 50 Issue 4 Pages
1037-1038
Published: April 15, 1981
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Fluctuation in the linear feedback oscillator is studied experimentally. An increase of the fluctuation near the hard-mode instability point is ascribed to growth of irreversible circulation of the fluctuation.
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Fumio Yoshida, Yukio Okwamoto, Tsuneyoshi Nakayama
1981 Volume 50 Issue 4 Pages
1039-1040
Published: April 15, 1981
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By the use of molecular dynamics technique, we studied the thermodynamic properties of the anisotropic two-dimensional (2D) sine-Gordon lattice. Anisotropy parameter γ is introduced as the ratio of the strength of stretching to that of shear coupling. Energy-temperature curves are calculated with varying γ. We found that the peak temperature of specific heat changes with γ. These observed thermodynamic properties are analyzed in the case of 1D and nearly isotropic 2D system.
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Masayuki Kawakami, Yutaka Yoshida, Takuro Nakamichi, Shoji Ishida, Hir ...
1981 Volume 50 Issue 4 Pages
1041-1042
Published: April 15, 1981
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NMR and magnetization were measured at 4.2 K for Mn
2VAl with the L2
1 structure. The
27Al,
51V and
55Mn NMR signals were observed by the spin echo technique in zero external field at 28.2, 71.5 and 104.2 MHZ which correspond to the hyperfine fields of −25.4, −63.9 and −98.7 kOe, respectively. The saturation magnetization was determined to be 56.8 emu/g and the high-field susceptibility between 20 and 80 kOe to be 1.38±0.24×10
−6 emu/g. From magnetic field dependence of the NMR frequencies and the high-field susceptibility, it was concluded that Mn
2VAl is a simple ferromagnet. The hyperfine field was discussed on the basis of the results of a band calculation.
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Gendo Oomi, Nobuo Mori
1981 Volume 50 Issue 4 Pages
1043-1044
Published: April 15, 1981
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Pressure dependence of the lattice constant is measured for the pressure-stabilized fcc phase of an Fe
70Ni
30 Invar alloy by high pressure X-ray diffraction method at 77.4 K. The bulk modulus
B in the ferromagnetic phase is obtained to be (14±1)×10
2 kbar. A discontinuous increase in
B,
ΔB, is found to be
ΔB≈700 kbar near 64 kbar. The magnitude
ΔB at 77.4 K is the same as that observed at the ferromagnetic to paramagnetic phase transition at room temperature around 15 kbar.
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Yoshiro Sasaki, Kunihiko Yamaguchi, Yuichiro Nishina
1981 Volume 50 Issue 4 Pages
1045-1046
Published: April 15, 1981
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The presence of the second indirect edge in GaS is pointed out through the analyses of the modulated spectroscopic data. The energy of the second indirect exciton at the M-point of the Brillouin zone is about 50 meV higher than that of the first one at 2.595 eV at the K- or H-point.
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Yoshio Kaneko, Koichi Morimoto, Takao Koda
1981 Volume 50 Issue 4 Pages
1047-1048
Published: April 15, 1981
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Optical reflection spectra have been measured on CaS single crystal at 77 K by using synchrotron radiation. Spectral features observed in 5∼6 eV are assigned to the band edge excitons, while structures observed in 25∼35 eV are ascribed to the Ca 3p-core excitons for the first time in II
a–VI compound crystals. The latter spectra can be accounted for quite well by the ligand field model by Satoko and Sugano.
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Sachio Watanabe
1981 Volume 50 Issue 4 Pages
1049-1050
Published: April 15, 1981
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Density-dependent electron mobility in non-polar fluids is calculated along critical isotherm. As the critical point is approached, the mobility shows large drop under the influence of critical fluctuations. The possibility that the mobility maximum occurs at a density larger than critical density is indicated.
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Fumio Komori, Shun-ichi Kobayashi, Youiti Ootuka, Wataru Sasaki
1981 Volume 50 Issue 4 Pages
1051-1052
Published: April 15, 1981
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The electrical transport properties of highly resistive films of copper were studied. Logarithmic variations of the conductivity with temperature and magnetic field were observed. Magnetoconductivity was strongly anisotropic. The results are discussed with the recent theories of electron localization in a two dimensional metal.
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Hideo Sugai, Yoshinobu Koji
1981 Volume 50 Issue 4 Pages
1053-1054
Published: April 15, 1981
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Spatial pitch of the nonlinear amplitude oscillation of electron cyclotron waves is examined quantitatively. Parameter values for an experiment designed to observe the nonlinear cyclotron damping are proposed.
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Yosinori Yamamoto, Éi Iti Takizawa
1981 Volume 50 Issue 4 Pages
1055-1056
Published: April 15, 1981
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The non-linear partial differential equation:
ut+(45⁄2)δ
2u2 ux−
uxxxxx=0,
has solutions expressed by elliptic functions. A solitary wave solution is also found to be
u=±\sqrtκ⁄3δ[3 \sech
2 (
A(ξ−ξ
0))−1], with ξ=
x−(9δκ
t⁄2),
A=\sqrtδ(
e1−
e3)⁄2,
e1=−2
e3=2\sqrtκ⁄(3δ), and any constants ξ
0 and κ.
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Susumu Ohya, Mitsutaka Kanazawa, Naoshi Mutsuro, Tsutomu Tamura, Zyun- ...
1981 Volume 50 Issue 4 Pages
1057-1062
Published: April 15, 1981
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The decay of
99mNb to the levels in
99Mo has been studied using β- and γ-spectroscopic techniques in singles and coincidence modes. A total of 143 γ rays were observed. Ninety-eight γ rays have been placed into the decay scheme involving 31 excited levels in
99Mo. Spin and parity assignments for the levels have been deduced using β-decay log
ft values, γ-ray transition rates and reaction data in the literature.
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Chiaki Murase
1981 Volume 50 Issue 4 Pages
1063-1066
Published: April 15, 1981
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A renormalization group approach in real space is applied to the bond percolating square lattice in two dimension using two scaling transformations proposed by Reynolds
et al. (Reynolds’s method) and by Yuge (Yuge’s method). The renormalization transformation
Rb(
p), the eigenvalue λ(
b) and the correlation length critical exponent ν(
b) are calculated exactly by changing the scale of length
b=4 for Reynolds’s method and
b=5⁄\sqrt2 and 6⁄\sqrt2 for Yuge’s method. The true critical exponent ν is estimated ν=1.341 and 1.337 by extrapolation, respectively. Discussions are made on the results.
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Masahito Hoshino, Huzio Nakano, Hatsuo Kimura
1981 Volume 50 Issue 4 Pages
1067-1072
Published: April 15, 1981
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By applying the method of symmetry breaking potential to the three direction model of hard rods with an attractive pair interaction, the effect of pressure on the Nematic-Smectic A transition is investigated. The curve of that transition temperature versus pressure as well as some other results agree with the experimental results qualitatively. It is shown that the tricritical point is possible to appear on that curve, by paying attention on the effect of attractive pair potential.
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Osamu Aono
1981 Volume 50 Issue 4 Pages
1073-1074
Published: April 15, 1981
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It is shown in an elementary manner that the
H function composed of the distribution function averaged over a time interval decreases monotonically to an equilibrium value with the increasing time interval.
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Sei-ichi Takase, Hajime Takayama
1981 Volume 50 Issue 4 Pages
1075-1081
Published: April 15, 1981
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Random two-dimensional (25×25) Ising spin systems with the nearest neighbor interactions
Jij which are distributed according to Gaussian distributions are investigated by computer experiments. We obtain, as the functions of the mean \bar
J, magnetization and energy of the ground states, and the temperature
Tc,q (
Tc,m) below which the Edwards-Anderson order parameter
q (magnetization
m) is finite. Qualitative interpretations of the phase diagram thus obtained, as well as those of clustering features observed in this model system, are presented.
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Masakatsu Umehara
1981 Volume 50 Issue 4 Pages
1082-1090
Published: April 15, 1981
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Effect of the electron-phonon interaction on the large self-trapped magnetic polaron is studied for the antiferromagnetic semiconductor at
T=0 K, in which both the acoustical and the optical phonon branch are taken into consideration. The electron-phonon interaction couples the magnetic polaron with the lattice deformation and thus reduces the radius of the magnetic polaron and stabilizes it. As the effective radius of the magnetic polaron becomes larger, the interaction with the optical branch is more effective than that with the acoustical branch. Furthermore, the self-trapped magnetic polaron in EuTe and its possibility are discussed on the basis of the detailed calculation. Some comments and discussions for related experimental results for EuTe are given. Effect on the small self-trapped magnetic polaron is also discussed on the basis of a simplified model.
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Kêitsiro Aizu
1981 Volume 50 Issue 4 Pages
1091-1094
Published: April 15, 1981
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The meaning of catastrophe index is explained over again. For every prototype point group and every soft mode irreducible representation with wavenumber zero, the catastrophe indices are evaluated; all the results are summarized into five propositions.
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Sachio Watanabe
1981 Volume 50 Issue 4 Pages
1095-1102
Published: April 15, 1981
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Electron mobility in non-polar fluids near critical points is investigated. Excess electrons in the fluid are very strongly scattered by the critical fluctuations, which thus causes large mobility drop near the critical point. The calculated mobility drop qualitatively reproduces experimental results, but quantitative agreement is not obtained. Such strong scattering of the electrons seems to lead the state different from quasi-free electron state. Effect of the new state on the mobility is discussed.
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Kohji Eguchi, Hironobu Fujii, Hiroshi Fujiwara, Nobuo Iwata, Tetsuhiko ...
1981 Volume 50 Issue 4 Pages
1103-1108
Published: April 15, 1981
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Measurements of magnetization at 4.2 K and paramagnetic susceptibility up to room temperature have been done on Gd–Sm single crystals and polycrystals less than 30 at.% Sm concentration. The magnetic structure is a ferrimagnetic configuration in the ordered regions for the measured samples. The magnetocrystalline anisotropy constants
K20 and
K40 were determined from the analysis of magnetization curves on the basis of the molecular field theory. The values of
K20 and
K40 are negative and positive, respectively, in all concentration ranges, and the magnitude increase quadratically with increasing Sm concentration. From these results, the values of the anisotropic exchange interaction between two magnetic ions in the Gd–Sm alloys,
K20 (AEI)
Gd–Sm and
K20 (AEI)
Sm–Sm, were estimated to be 42 and −24 cm
−1, respectively.
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Muneaki Fujii, Fumihiro Wakai, Hisashi Abe, Akira Hirai
1981 Volume 50 Issue 4 Pages
1109-1118
Published: April 15, 1981
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The angular dependences of
63Cu and
65Cu NMR frequencies in a single crystal of a ferromagnetic K
2CuF
4 with an external field of 1.4 T at 1.2 K were measured carefully. The spectrum showed a strong anisotropy, which is characteristic to the Jahn-Teller Cu
2+ ions. To analyse the spectrum, we solved the eigen value problem exactly and determined the values of the nuclear spin Hamiltonian parameters. The asymmetry parameter of the hyperfine field was larger than that of the electric field gradient. This result was consistent with the calculated one based on the one ion model. By changing the direction of the external field, some resonance lines disappeared and the other lines appeared. Such ‘cross-over’ phenomena could be understood qualitatively, by considering the angular dependences of their transition probabilities.
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Haruo Yoshida, Takuma Ishikawa
1981 Volume 50 Issue 4 Pages
1119-1125
Published: April 15, 1981
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The transverse component of the dynamic form factor (
Remark: Graphics omitted.) of the Ising-like linear chain at various temperatures is studied by the perturbation theory about the transverse part of the Hamiltonian. The dynamic form factor (
Remark: Graphics omitted.) for both the ferromagnetic and antiferromagnetic couplings has the three-peak structure for
k=0 at finite temperatures, and this structure persists even for any wave vector
k and at any high temperature. Many interesting characters in (
Remark: Graphics omitted.) are obtained. The
k-dependence of width of the absorption peak is remarkable in the antiferromagnetic case. The absorption peak has a finite width even at absolute zero except for
k=π⁄2 in the antiferromagnetic case, while the shape of the absorption peak is reduced to a infinitely sharp one as the temperature is decreased to absolute zero in the ferromagnetic case.
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Masaaki Kontani, Yoshika Masuda
1981 Volume 50 Issue 4 Pages
1126-1132
Published: April 15, 1981
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The effect of spin fluctuations in antiferromagnetic alloys has been studied by using the generalized Shibatani-Motizuki-Nagamiya model with the renormalized spin-fluctuation theory and the coherent-potential approximation. The concentration dependence of the Néel temperature
TN and the wave vector at
TN is calculated by taking the parameters included in the model so as to be suitable for Cr
1−xV
x alloys. The experimental results of these quantities in Cr
1−xV
x alloys are explained very well by these calculations. The temperature dependence of the nuclear spin relaxation rate 1/
T1 is also calculated for various impurity concentrations.
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Masatsugu Suzuki, Hironobu Ikeda
1981 Volume 50 Issue 4 Pages
1133-1139
Published: April 15, 1981
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The magnetic susceptibility χ
a in the two-dimensional ferromagnet K
2CuF
4 has been measured near
Tc=6.25 K with the magnetic field
H applied in the direction parallel to the
a-axis in the easy plane. The field and temperature dependences of χ
a are determined and the static scaling hypothesis is examined. Above
Tc, it is found that χ
a is described by a scaling function, χ∼
H−λ Ψ(
H⁄
t1⁄μ), where
t=|
T⁄
Tc−1|, λ=0.82±0.05 and μ=0.83±0.05. The critical exponents of magnetization and susceptibility, β and γ, are estimated as β=0.22±0.05 and γ=0.99±0.05 from the relations β=(1−λ)⁄μ and γ=λ⁄μ. The susceptibility χ
a has a broad peak in an external magnetic field above
Tc which shifts to higher temperatures as the mannetic field increases. This broad peak corresponds to the appearance of the magnetic-field-induced ferromagnetic state.
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Yoshiaki Tanaka, Norikiyo Uryû
1981 Volume 50 Issue 4 Pages
1140-1148
Published: April 15, 1981
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In the Bethe lattice in which the Bethe approximation is exact, the Curie temperatures of the Ising model with spin (
Remark: Graphics omitted.) are obtained exactly by generalizing the method of Katsura and Takizawa for the system with (
Remark: Graphics omitted.). This method is applied to the planar rotator model on the infinite Cayley tree, and the critical temperature and the susceptibility are rigorously calculated. It is pointed out that the susceptibility diverges below the critical temperature, on the other hand the spontaneous magnetization vanishes as the ground state is degenerated infinitely.
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Masatsugu Suzuki
1981 Volume 50 Issue 4 Pages
1149-1153
Published: April 15, 1981
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A dynamic scaling form is presented for the ultrasonic attenuation of antiferromagnets due to the order-parameter relaxation, α
R. The attenuation α
R takes a maximum value below the Néel temperature
TN. The frequency dependence of the maximum value of α
R, α
Rmax, is derived from this scalins form by assuming the static scaling hypothesis for the wave-vector dependent staggered susceptibility χ(
k) (
k and ω are wave vector and angular frequency of sound waves). This theory is compared with experimental results on Rb
2CoF
4 and MnF
2; α
Rmax∝ω
1.15 for Rb
2CoF
4 and α
Rmax∝ω
0.4 for MnF
2. It is found that this difference between Rb
2CoF
4 and MnF
2 is mainly due to the difference of the behaviour of χ(
k) below
TN.
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Shizuo Kadowaki, Minoru Takahashi
1981 Volume 50 Issue 4 Pages
1154-1161
Published: April 15, 1981
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The magnetostriction constants, λ
100 and λ
111, of f.c.c. Ni–Co alloys have been measured in the temperature range between 77 and 450 K using the strain gauge technique. The sign of λ
100 changes from negative to positive with increasing Co content in the temperature range between 77 and 450 K, while the values of λ
111 are negative. The magnitude of both constants decreases monotonically with increasing temperature. The present data were analyzed by Néel’s theory and the coefficient of pseudo-dipole interaction was estimated. The temperature dependence or the magnetoelastic coupling constants does not obey the third power law of the reduced magnetization. The contribution of the magnetoelastic coupling effect to the anisotropy constant,
K1, were evaluated. The contribution is too small to explain the change of sign in
K1 with increasing temperature and/or Co concentration.
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Kazuo Ueda
1981 Volume 50 Issue 4 Pages
1162-1172
Published: April 15, 1981
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The periodic Anderson model is investigated with particular emphasis on the two important natures of the mixed valence compounds: The Curie type behavior of the susceptibility at high temperatures and the non-magnetic ground state. The free energy as a function of the total magnetization is calculated by introducing the number and the magnetization of
f electrons as extra explicit variables and with the use of an expansion from the strong coupling limit. The present strong correlation theory predicts not only the phase transition from the magnetic ground state to the non-magnetic one as the
f level is raised but also the Curie susceptibility with the correct Curie constant.
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Kazuo Ueda
1981 Volume 50 Issue 4 Pages
1173-1179
Published: April 15, 1981
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The specific heat of the periodic Anderson model is investigated based on a previously developed theory which takes full account of the effect of strong correlation. The specific heat shows a Schottky type behavior which is due to the appearance of the “local” moments. The static density-density response which is a measure of the charge fluctuations is also investigated. It is shown that the density-density response at high temperatures obeys Curie law whose Curie constant is smaller than that of the spin susceptibility depending on the occupancy of the
f states. The temperature dependence of these physical quantities is satisfactory in view of the mixed valence phenomena.
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Nozomu Inoue, Hiroshi Yasuoka, Masaaki Matsui, Kengo Adachi
1981 Volume 50 Issue 4 Pages
1180-1188
Published: April 15, 1981
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59Co spin-echo NMR were carried out for metallic compounds Co(S
xSe
1−x)
2 with pyrite structure over the entire composition range to investigate the microscopic magnetic properties of this system. From the results obtained, it is concluded that the character of Co atoms is unique in each composition with 0≤
x\lesssim0.6, whereas above about
x=0.86 two kinds of Co atoms coexist, one is non-magnetic and the other is ferromagnetic with 0.85 μ
B. It is also shown that the effect of electron correlations on the magnetism increases with increasing sulphur content. The characteristic field-induced metamagnetic transition around
x=0.88 is concluded to be due to the progressive-discontinuous transition from the nonmagnetic state to the ferromagnetic state with increasing external magnetic field. Discussions on the mechanism of the coexistence of nonmagnetic and ferromagnetic Co atoms and the composition dependence of the fraction of the ferromagnetic Co atoms are briefly given.
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Shigeyuki Murayama, Hiroshi Nagasawa
1981 Volume 50 Issue 4 Pages
1189-1193
Published: April 15, 1981
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NMR studies of α-Mn metal have been carried out in the paramagnetic phase between Néel temperature and room temperature. Different temperature dependence or the Knight shift has been observed for each Mn atom at four inequivalent crystallographic sites and a maximum of the Knight shift has been found from the resonance line for site I. Temperature dependence of the quadrupole interaction parameters has been determined from the resonance line for site III and site IV.
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Hiroyuki Okura, Kiyoshi Kawamura, Takuro Tsuzuku
1981 Volume 50 Issue 4 Pages
1194-1199
Published: April 15, 1981
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Magnetic susceptibilities of compression annealed pyrolytic graphite intercalated with iodine monochloride (ICl) and of pyrolytic carbon substitutionally doped with boron (B) have been measured between 77 K and 300 K as functions of temperature and impurity concentration. The results are discussed in terms of McClure’s theory based on the Slonczewski-Weiss band model. A numerical computation of the carrier concentration has led to an evaluation of the hole production rate of impurities; 67% for B and 5% for ICl. The low hole production rate of ICl seems to be ascribed to the clustering of intercalants taking place between carbon layers.
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Kenji Shimizu, S. K. Dhar, R. Vijayaraghavan, S. K. Malik
1981 Volume 50 Issue 4 Pages
1200-1202
Published: April 15, 1981
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NMR of
55Mn has been observed in magnetically ordered state of cubic Laves phase compounds GdMn
2, TbMn
2, DyMn
2 and HoMn
2 and in hexagonal Lave phases ErMn
2 and TmMn
2. Magnetization and neutron diffraction studies have shown non zero Mn moment in cubic compounds only. Accordingly, we find that hyperfine fields at Mn site are larger in cubic than in hexagonal compounds. The observed hyperfine field values are used to estimate Mn moments in these compounds.
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Tsutomu Sano, Shuzo Kawarazaki, Satoshi Iida, Nobuhiko Kunitomi
1981 Volume 50 Issue 4 Pages
1203-1206
Published: April 15, 1981
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The change in the antiferromagnetic properties of chromium caused by alloying with a small amount of beryllium (less than 6 at.%) was studied by neutron diffraction for powder and single crystal specimens and also by electrical resistivity measurements at temperatures above 80 K. The results indicate that addition of Be causes a decrease of the Néel temperature, spin flip temperature, magnetic moment and the wave vector of the spin density wave. This behavior is quite different from that observed in the dilute Cr alloys containing other species of non-transition elements.
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Yoshie Matsuo, Tomoko Makita, Toshiharu Suzuki, Akira Nagasawa
1981 Volume 50 Issue 4 Pages
1207-1208
Published: April 15, 1981
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The elastic constants of single crystal of β
1-AgCd alloy with 47.9±0.1 at.%Cd have been measured in a temperature range between 180 K and 360 K, using a ultrasonic pulse-cho overlapping method. It is found that with increasing temperature, the elastic constants
CL=(
C11+
C12+2
C44)⁄2 and
C44 decrease linearly but
C′=(
C11−
C12)⁄2 increases. In addition, this alloy shows a high elastic anisotropy in comparison with other Ag-based β
1-phase alloys such as AgMg and AgZn.
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Eiji Anno, Ryosuke Hoshino
1981 Volume 50 Issue 4 Pages
1209-1216
Published: April 15, 1981
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Lattice defects in the particle of silver island films have been observed by electron microscope. Transmittance spectra of these films were measured in the region of plasma resonance absorption and compared with spectra calculated by the classical model of the size effect. The agreement between experimental and calculated half-widths was found for particles from 18 to 22 A in diameter, but for the particles larger than 26 A the experimental half-width was found to be broader than the calculated one. This discrepancy is attributed to the increased electron-lattice defects scattering. Electron-lattice defect relaxation frequencies calculated from experimental half-widths increase with the particle size. This size dependence is interpreted by the particle growth due to the agglomeration. The exclusion of lattice defects by annealing was difficult.
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Rumiko Inada, Yoshichika Onuki, Sei-ichi Tanuma
1981 Volume 50 Issue 4 Pages
1217-1221
Published: April 15, 1981
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The magnetic susceptibility and its anisotropy of 1T-TaS
2 were measured from 300 K to 1.2 K. The paramagnetic part observed by DiSalvo
et al. was confirmed and was found to increase rapidly with the temperature decrease below liquid helium temperature. The paramagnetic moment has a non-linear field dependence which cannot be explained by the Brillouin function. The origin of this paramagnetism seems not to be magnetic impurities but the correlation effect of Anderson localized electrons associated with a large amplitude of the charge density wave.
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Masasi Inoue, Hisato Oshima, Motoji Morisaki, Hisao Yagi, Hoong Kun Fu ...
1981 Volume 50 Issue 4 Pages
1222-1226
Published: April 15, 1981
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Magnetization measurements have been carried out to study various types of magnetism in degenerate magnetic semiconductors Sn
1−x(Me)
xTe with different 3d transition metals Me=Cr, Fe, Co, and Ni. Of these impurities with
x=1 at.%, only Cr and Fe act as ferromagnetic centers, while Co and Ni are magnetically ineffective in the host SnTe matrix which has a strong diamagnetic background. In particular, Sn
1−xCr
xTe (0.2
at.%<
x<2
at.%) exhibits a ferromagnetic transition at the Curie temperature
Tc which varies from 150 K to 300 K depending on the Cr concentration and the annealing. This transition was confirmed by the anomalies in the spin resonance (g-value and linewidth), the resistivity, and the specific heat.
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Minoru Itoh, Ken-ichi Kan’no, Nobufumi Mori, Yoshio Nakai
1981 Volume 50 Issue 4 Pages
1227-1232
Published: April 15, 1981
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Recombination processes of radiation-induced defects in KBr have been studied below 60 K by means of detecting the polarization of the thermoluminescence. A definite 〈110〉 dichroism is found in both the π and σ emission components of the glow peak at ∼28 K in the crystal where the
H and
VK centers have been aligned previously along the [1\bar10] direction by irradiating with [110]-polarized light. Since the
H center is known to lose its memory of orientation around 16 K, the results obtained lead to the conclusion that the glow peak near 28 K arises from the recombination of free electrons with
VK centers, not from the
F-
H recombination.
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Syuji Kawada
1981 Volume 50 Issue 4 Pages
1233-1240
Published: April 15, 1981
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Representations of configurational entropy of ice Ih are obtained following the ways of Pauling’s estimation. A phenomenological free energy expression is proposed using one of the entropy representations together with the terms of dipole-dipole interaction among eight sublattices. The experimental results of anisotropic static dielectric constants and their temperature dependences are well understood through this free energy expression. Effective dipole moments of a water molecule in H
2O and D
2O ice Ih are evaluated, respectively, as 2.30 and 2.38 Debye.
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Yoshihiro Goto
1981 Volume 50 Issue 4 Pages
1241-1246
Published: April 15, 1981
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The complex dielectric constant of single crystal of ferroelectric Pb
5Ge
3O
11 has been measured in a frequency range below kHz order as a function of temperature. The dielectric dispersion observed around and above the Curie temperature
Tc is very much dependent on the sample thickness; the conventional Cole-Cole plot does not form a circular arc. In addition, an anomalous dip of the real part of the complex dielectric constant has been frequently observed at
Tc in a frequency range of kHz order; such a dip can be observed only in the specimen thiner than 1 mm. The observed dielectric dispersion is discussed.
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Kiyosi Motida
1981 Volume 50 Issue 4 Pages
1247-1248
Published: April 15, 1981
Released on J-STAGE: May 29, 2007
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It is shown that there exists a linear correlation between the Szigeti charge and the hyperfine constant of the doped
151Eu
2+ ion in the divalent metal compounds. It is pointed out that this correlation is the same type as the case of the Mn
2+ ion given previously by the author (J. Phys. Soc. Jpn.
49 (1980) 213.), although in the Eu
2+ ion case the 4
f electrons possessing the spin have no appreciable covalency unlike the case of Mn
2+ ion.
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Shunsuke Hirotsu, Yasuo Kunii
1981 Volume 50 Issue 4 Pages
1249-1254
Published: April 15, 1981
Released on J-STAGE: June 01, 2007
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Brillouin scattering spectra of perovskite-type crystal CsPbCl
3 have been measured above its cubic-tetragonal phase transition temperature,
Tc=47°C. The three elastic constants
c11,
c12 and
c44 were determined in a wide temperature range. The result agrees quite well with that of the previous ultrasonic measurement. This fact shows that there is no detectable elastic dispersion between 10
7 Hz and 10
10 Hz. An analysis using a single relaxation time model shows that the elastic relaxation time is shorter than 1×10
−11 sec at
T=
Tc+3°C. The soft-mode model rather than the order-disorder one seems to be more appropriate to a description of the cubic-tetragonal phase transition in this crystal.
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Yoshihiro Ishibashi
1981 Volume 50 Issue 4 Pages
1255-1258
Published: April 15, 1981
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A sequence of phase transitions in biphenyl including two different incommensurate phases is tentatively interpreted within the Landau theory. In the thermodynamic potential functional the Lifshitz term and the non-Lifshitz term coexist, both favoring the incommensurate phases. It is pointed out that the term of the fourth order in the transition parameters and the second order in the modulation wavenumber plays an important role in reproducing the incommensurate-incommensurate transition.
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Tomoyuki Hikita, Makoto Kitabatake, Takuro Ikeda
1981 Volume 50 Issue 4 Pages
1259-1265
Published: April 15, 1981
Released on J-STAGE: June 01, 2007
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Rayleigh-Brillouin scattering in NH
4Cl has been studied under hydrostatic pressure. Brillouin shifts of the longitudinal phonons propagating along the 〈100〉 and 〈110〉 directions and of the transverse phonons propagating along the 〈110〉 direction are measured as a function of temperature at four fixed pressures up to 2.3 kbar. All components increase almost linearly with decreasing temperature in the disordered phase and show incremental increases similar to the temperature dependence of the long range order parameter in the ordered phase. It was found that the longitudinal modes exhibit large despersion effect even at high pressures. On the other hand, the transverse mode appears to give no dispersion effect. The intensity of the Rayleigh component in the VV polarization condition increases as the temperature approaches the transition point, while that in the VH polarization does not show such anomalous increase.
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Katsuhiko Hasebe
1981 Volume 50 Issue 4 Pages
1266-1274
Published: April 15, 1981
Released on J-STAGE: May 29, 2007
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The crystal structure of ammonium sulfate is studied at −140, −90, −64 and −53.5°C in the ferroelectric phase, and at −48.5 and −40°C in the paraelectric phase, by the use of the data collected by a four-circle diffractometer. The difference Fourier synthesis at −53.5°C shows a clear indication of the disordering of the ammonium ion I but does not show the disordering of the sulfate ion. The configuration of the sulfate ion below
Tc can be derived from that above
Tc by a condensation of one of the librational
B1u symmetry modes. The order parameters of two kinds of ammonium ions are determined by the use of the reflection data below
Tc. From the temperature dependence of the displacement of the sulfate ion and order parameters of two kinds of ammonium ions below
Tc, a pseudospin-phonon coupled model is proposed.
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Katsunori Mori, Norihito Tamura, Yoshitami Saito
1981 Volume 50 Issue 4 Pages
1275-1280
Published: April 15, 1981
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Electrical Resistivity measurement has been made on intermetallic compound In
5Bi
3 over the temperature range of 1.3 to 400 K through the melting temperature. The superconducting critical fields have also been measured. It was observed that the temperature dependence of the ideal resistivity after subtraction or the residual resistivity varied as
T1.8 between 4.2 K and 30 K and as
T0.2 at high temperatures. Data for the high temperature resistivity have been analyzed with use of a phenomenological model based on the idea that the ideal resistivity must approach some limiting value where the mean free path becomes comparable to the interatomic spacing.
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Hiroto Tateno
1981 Volume 50 Issue 4 Pages
1281-1284
Published: April 15, 1981
Released on J-STAGE: June 01, 2007
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An attempt has seen made to study the behaviour of dislocation atmosphere in NaCl crystals by internal friction and conductivity measurements. From a migration energy of divalent impurity-vacancy complex,
Em, in pure NaCl crystals, and a binding energy of the complex,
Eb, an activation energy for exchange between the divalent impurity and neighbouring vacancy is deduced as
Ea=
Em+
Eb=0.82±0.05 eV. The
t1⁄3 dependence of unpinning process of point defects is explained through simple calculation, assuming that the distribution of divalent impurity-atmosphere is controlled by elastic interaction potential, and not by the electrical potential of dislocation.
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Masayoshi Inoue, Mamoru Tanibayashi, Hiroto Tateno
1981 Volume 50 Issue 4 Pages
1285-1290
Published: April 15, 1981
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Recovery of the internal friction is studied theoretically where the string model for a dislocation has been used. It is considered that weak pinners of dislocations move from their original positions when an applied oscillating stress becomes high enough to produce full breakaway. This motion is caused by an elastic force which is arising from an interaction between weak pinners and the oscillating dislocation. The interaction is calculated rigorously and it shows that weak pinners localize at the maximum displacements of the oscillating dislocation. After switching off the oscillation, weak pinners return to their original positions by a similar elastic force. This process gives an aging law
t1⁄3 which agrees with an experiment on NaCl. Observed wave form of the electric potential difference caused by charged oscillating dislocations in NaCl is discussed also using this new model.
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Kuon Inoue, Nobutoshi Asai, Toshiyuki Sameshima
1981 Volume 50 Issue 4 Pages
1291-1300
Published: April 15, 1981
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The fundamental features of the hyrer-Raman scattering phenomenon due to Raman-inactive mode of lattice vibration have been experimentally studied for SrTiO
3, with special emphasis on polarization properties and an application of the hyper-Raman scattering to observation of the soft mode. The results of polarization properties are compared with the selection rules based on group theory. Variation of the “ferroelectric” soft-mode has been measured as a function of temperature from 300 K to 4.6 K. Further, a comparison between the forward- and right-angle scatterings is given from the experimental point of view.
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Jumpei Okada, Yukio Fukuda, Masahiro Matsuoka
1981 Volume 50 Issue 4 Pages
1301-1309
Published: April 15, 1981
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Second harmonic generation (SHG) in atomic Li vapor is studied when the 2
2S1⁄2–3
2S1⁄2 two-photon transition is resonantly excited. This is an SHG in a medium with inversion symmetry, with no externally apptied electric or magnetic field, and with no apparent multipole moments associated with the resonant excitation. The SH polarization is found to be parallel to the intensity gradient of the incident laser beam when a cylindrical lens focusing is applied. The mechanism of this highly forbidden SHG is explained by the radial electric field induced by free expansion of photo-electrons around the laser beam axis.
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