-
M. Lakshmanan, S. Ganesan
1983 Volume 52 Issue 12 Pages
4031-4033
Published: December 15, 1983
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A generalized version of the Hirota’s equation with linear inhomogeneities is shown to be equivalent to a generalized continuum Heisenberg ferromagnetic spin chain equation as well as to a generalized Wadati-Konno-Ichikawa-Shimizu (WKIS) type equation, both from geometrical and gauge considerations. The corresponding spectral problems are associated with moving eigenvalues.
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Takeo Izuyama, Takao Yamamoto
1983 Volume 52 Issue 12 Pages
4034-4037
Published: December 15, 1983
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The Schultz-Halperin-Henley model for an assembly of adsorbed atoms on an anisotropic rectangular lattice is considered. The Kosterlitz-Thouless dislocations are neglected. A rigorous solution of such model is presented by revising the free Fermion approach into an exact formalism. A complete phase diagram of this model is given. A new phase is found. The critical exponents are obtained. It is found that the particle-hole symmetry does not hold in the exact prediction. Finally an approach to a more extensive model including the KT dislocations is briefly presented.
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Hiromitsu Hamabata, Masaki Takashima
1983 Volume 52 Issue 12 Pages
4038-4040
Published: December 15, 1983
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The nature of the neutral state in convective instability in a horizontal fluid layer with uniformly distributed internal heat sources is investigated using linear stability theory. The power series method is adopted to obtain the eigenvalue equation which is then computed numerically. It is shown that, as assumed before, the neutral state is indeed a stationary rather than an oscillatory one.
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Hikaru Terauchi, Satoshi Iida, Kazuhiro Tanabe, Kenji Kikukawa, Hirono ...
1983 Volume 52 Issue 12 Pages
4041-4043
Published: December 15, 1983
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An EXAFS study of Au
0.23Cu
0.30Zn
0.47 just above the martensitic phase transition temperature has been carried out. The local structure around Au and Cu atoms is determined. It has been shown that a considerable number of Au and Cu atoms displace from the regular sites of the bcc lattice along the [110] direction, even though the average structure maintains the regular cubic lattice. These results suggest that local defects are randomly distributed in the premartensitic phase.
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Satoshi Iida, Hikaru Terauchi
1983 Volume 52 Issue 12 Pages
4044-4047
Published: December 15, 1983
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From the measurements of dielectric constants and X-ray diffraction profiles on a random mixture of a ferroelectric and an antiferroelectric, Rb
1−x(NH
4)
xH
2PO
4, for 0.3\lesssim
x\lesssim1.0, the phase diagram was determined. For 0.8\lesssim
x\lesssim1.0 the long range antiferroelectric phase was observed as like in pure NH
4H
2PO
4. A dipole-glass phase was found in the intermediate concentration range (
x\lesssim0.7).
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Tsuyoshi Murao, L. Couture
1983 Volume 52 Issue 12 Pages
4048-4051
Published: December 15, 1983
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The crystal field plays the important role in rare earth metals but experimental data and theoretical viewpoints do not well converge even in themselves, and this problem is discussed for the metals with dhcp structure. A useful similarity relation between the cubic site in dhcp and the lattice site in hcp is presented, which may be utilized to investigate the relative importance of the point charge contribution against the conduction electron contribution.
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Kiyoshi Murakawa
1983 Volume 52 Issue 12 Pages
4052-4055
Published: December 15, 1983
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If one operates the magnetization cycle: saturation magnetization in one direction→magnetic field zero→saturation magnetization in the opposite direction→magnetic field zero→saturation magnetization in the first stage direction→etc. continuously on a Ni 52%–Fe alloy bar, the coercive force in the ascending branch is always found to be larger than the coercive force in the descending branch. This is interpreted to be due to ferromagnetic memory-effect, because the first stage direction of saturation magnetization is memorized. Severe cold drawing of the bar tends to obscure the memory-effect.
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Masakiyo Horioka
1983 Volume 52 Issue 12 Pages
4056-4058
Published: December 15, 1983
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The complex dielectric constant of {N(CH
3)
4}
2ZnCl
4 crystal has been measured in the incommensurate phase in the frequency range from 30 kHz to 10 MHz. It has been found that the dielectric dispersion occurring along the ferroelectric
a-axis is of the Debye-type with a single relaxation time in the incommensurate temperature range except the close vicinity of the incommensurate-commensurate phase transition point
Tc. In the incommensurate phase, the relaxation time increases nearly in inverse proportion to (
T−
Tc) and reaches to the value of about 1.2×10
−7 sec at just above
Tc.
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Shunji Kawamoto
1983 Volume 52 Issue 12 Pages
4059-4065
Published: December 15, 1983
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New nonlinear partial differential equations reducible to the Painlevé equations are derived through special transformations constructed by similarity variables of well-known one-dimensional soliton equations. Also, it is discussed that there exist identity transformations, which transform an equation into the original one.
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Tadao Ishii
1983 Volume 52 Issue 12 Pages
4066-4073
Published: December 15, 1983
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Discussion of the static structure factor
S(
q) for the Frenkel-Kontorowa systems is made on the basis of a high-temperature expansion of the transfer-integral equation [TIE]. The approximate solution of the TIE can be expressed in terms of an arbitrary order of the modified Bessel function
In, the use of which for
S(
q) within the 20th-order of
In reveals that
S(
q) converges quite well, for example, in the regions of the substrate potential
U⁄
kBT=
Uβ\lesssim4 for the correlation length κ
a−1=3.1. Application to the K-hollandite [K
1.54Mg
0.77Ti
7.23O
16] shows that
S(
q) for
Uβ\lesssim4 does not properly reproduce the experimental result, but gives rise to a consistent result for
Uβ=8 and κ
a−1=3.1 whose values are in good agreement with 6 and 5.1, respectively, theoretically obtained by Beyeler-Pietronero-Strässler from their configurational model analysis. An effect of
U turns out to be evident in the K-hollandite.
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Hidetoshi Konno
1983 Volume 52 Issue 12 Pages
4074-4080
Published: December 15, 1983
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Steady inhomogeneous patterns of the μ
* model system for superconductor driven far from equilibrium are numerically studied. We firstly check the applicability of the reductive perturbation method to inquire into pattern formation. Then it is shown that the “global-local” concept is expedient to understand the calculated inhomogeneous spatial patterns. Further the feasibility of the abnormal (negative) diffusion in open systems is demonstrated by deriving a reduced non-linear stochastic equation with effective negative diffusion coefficient from a generalized Haken-Zwanzing model. The way of thinking developed in this paper will be useful to understand the inhomogeneous patterns in other non-equilibrium open systems.
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Mizuhiko Saeki
1983 Volume 52 Issue 12 Pages
4081-4090
Published: December 15, 1983
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Time-convolution and time-convolutionless expressions for the quantal equation of motion for the linear response of a system under random perturbations to an external, time-varying driving field are derived from the stochastic quantal Liouville equation for the total system. They have forms convenient for the perturbational expansions in powers of the random perturbations. One is compared with another for two initial conditions. It is shown that the time-convolutionless form of equation prevails over the time-convolution form, especially when the effects of the random perturbations are discussed except in the narrowing limit or when the effects of interference of the external driving field and the random perturbations are discussed. The higher order expansions of these equations are mentioned.
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Mizuhiko Saeki
1983 Volume 52 Issue 12 Pages
4091-4098
Published: December 15, 1983
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An extended model of the Kubo-Anderson oscillator with random frequency modulation under the action of an external driving force is considered. The time-convolutionless and time-convolution equations of motion for the averaged linear response of the complex coordinate of this oscillator to the driving force are compared with the exact equation under the assumption that the random process of the frequency is Gaussian. It is shown that the time-convolutionless equation coincides with the exact one up to fourth order in powers of the random modulation, and that the time-convolution equation coincides with the exact one in the narrowing limit. For the Gaussian-Markoffian process, the exact solution is shown to coincide with the solution of the time-convolution equation up to second order in powers of the random modulation in the narrowing limit, but not for small times.
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Isao Harada
1983 Volume 52 Issue 12 Pages
4099-4106
Published: December 15, 1983
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Exact expressions for the wave-number dependent longitudinal and transverse susceptibilities of the one-dimensional Ising model with competing interactions are obtained by combining the linear response theory with the transfer matrix method. The longitudinal susceptibility exhibits a characteristic wave-number dependence, while the transverse susceptibility is independent of wave-number. Special attention is paid to the condition under which the longitudinal susceptibility has a maximum value at nonzero wave-number. Furthermore, the phase diagram of a system with weakly coupled Ising chains is considered in connection with the one-dimensional susceptibility.
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Fumio Abe, Kazuhiko Hara, Nobuhiro Kim, Kunitaka Kondo, Shigeyuki Miya ...
1983 Volume 52 Issue 12 Pages
4107-4117
Published: December 15, 1983
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The polarization of 2.4×10
5 Λ0 hyperons has been measured in inclusive production by 12-GeV protons on tungsten at three production angles, 3.5°, 6.5°, and 9.5°. In terms of Feynman’s
xF and the transverse momentum
pT of
Λ0, the kinematic range is 0.3≤
xF≤0.8 and 0.4≤
pT≤1.6 GeV/c. The
Λ0 was identified by detecting the proton and pion from the
Λ0→
pπ
− decay with a double-stage magnetic spectrometer, and its polarization was determined from a hybrid Monte Carlo analysis on asymmetries in the angular distribution of the decay products. The observed polarization is consistent with the data obtained at higher energies, indicating that the phenomenon of the inclusive
Λ0 polarization scales down to the 12-GeV region. The polarization at 12 GeV increases linearly with
pT up to 16% at
pT=1.0 GeV/c, showing a tendency to level off above that point.
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Kimiaki Fujiwara, Nobuyuki Toshima
1983 Volume 52 Issue 12 Pages
4118-4121
Published: December 15, 1983
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The cross sections of the electron capture from a hydrogen atom by a proton or by a helium ion are calculated by the close-coupling (cc) method at high energies up to 5.625 MeV/amu. The cc cross section is always smaller than the Brinkman-Kramers (BK) cross section and the ratio of them approaches to unity monotonically in disagreement with the results of Cheshire
et al. as the collision energy increases.
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Toshio Kusakabe, Nobuo Nagai, Hirofumi Hanaki, Tadahiko Horiuchi, Masa ...
1983 Volume 52 Issue 12 Pages
4122-4128
Published: December 15, 1983
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The single- and double-electron capture cross sections, σ
q,q−1 and σ
q,q−2 respectively, for Ne
q+ (
q=2∼5 and
q=2∼4) ions on He and H
2 have been measured in the energy range from 1.5 to 12 keV/
q. The results are consistent with the existing data except for
q=2 and are monotone against impact energy. The σ
q,q−1 values, which do not satisfy the known scaling laws, are fairly well explained by the classical one electron model, while the σ
q,q−2’s cannot be fitted to the reported scaling rule and model. Therefore our new model is applied that projectile ion captures one or two electrons from target in a statistical way.
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Tsunehiko Kakutani, Keiji Michihiro
1983 Volume 52 Issue 12 Pages
4129-4137
Published: December 15, 1983
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This paper deals with the marginal state of modulational instability of a nonlinear wave which is governed by a cubic nonlinear Schrödinger (shortly NS) equation far from the marginal state. Considering the gravity water wave as a typical example for which the coefficient of the nonlinear term of the NS equation does vanish at the marginal state, we reduce a new governing equation near the marginal state instead of the NS equation. Based on this new equation, the Benjamin-Feir instability of the Stokes wave is found to be enhanced by the higher order nonlinearity.
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Sadatoshi Taneda
1983 Volume 52 Issue 12 Pages
4138-4144
Published: December 15, 1983
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The structure of turbulent boundary layers on a flat plate is examined using flow visualization methods. The experimental results suggest that turbulent boundary layers consist of various kinds of instability waves. The main waves are T–S waves, G
1 waves and G
2 waves. The T–S wave is a large-scale two-dimensional wave produced as a result of the instability of the mean velocity distribution. The G
1 and G
2 waves are three-dimensional waves produced at the trough of T–S waves as a result of centrifugal instability.
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Hiromitsu Hamabata, Masaki Takashima
1983 Volume 52 Issue 12 Pages
4145-4151
Published: December 15, 1983
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The effect of uniform rotation on the onset of convective instability in a horizontal fluid layer with uniformly distributed internal heat sources is considered using linear stability theory. Under the assumption that the neutral state is a stationary one, the power series method is adopted to obtain the eigenvalue equation which is then computed numerically. The stability conditions influenced by uniform rotation are found for two sets of thermal boundary conditions.
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Yutaka Sasakura
1983 Volume 52 Issue 12 Pages
4152-4159
Published: December 15, 1983
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The semi-ellipse theorem for the heterogeneous rotating flow with respect to the two-dimensional disturbance is extended to the three-dimensional disturbance. Two assumptions of positive density gradient and positive Rayleigh-Synge’s discriminant
Φ are made. It is shown that the complex angular phase-velocity of any unstable mode must lie within the semi-ellipse whose major axis equals
b−
a, while its minor axis changes in length from
[1+4(
a⁄
b)
R(1+\sqrt1−4
R)
−2]
−1⁄2(
b−
a) if (
Φ⁄ρ
0)
m\gtrsim2
abto
b−
a as (
Φ⁄ρ
0)
m decreases below 2
ab,
R being (
Ω02⁄
Ω0′2)
m(ρ
0′⁄ρ
0r)
m, ρ
0(
r) the density,
Ω0(
r) the angular velocity of rotating flow,
a and
b its lower and upper bounds, respectively, and
r the radial distance. The prime denotes differentiation with respect to
r and the suffix m means the minimum value.
R must be less than 1/4 by the necessary condition for instability.
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Kenichi Nanbu
1983 Volume 52 Issue 12 Pages
4160-4165
Published: December 15, 1983
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Belotserkovskiy and Yanitskiy proposed stochastic laws for simulating molecular collisions in gas; these laws are consistent with the assumptions on which Kac’s master equation is built up. Firstly, it is shown that the laws can be derived directly from Kac’s master equation by use of the stochastic solution method recently proposed by the author. Secondly, by use of the laws the solution of Kac’s master equation is obtained and compared with the known exact solution of the Boltzmann equation. If the number of simulated molecules greater than about 40 is used, the obtained solution agrees with the exact solution.
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Yousuke Nakashima, Hideki Zushi, Kiyoshi Hanatani, Katsumi Kondo, Akih ...
1983 Volume 52 Issue 12 Pages
4166-4175
Published: December 15, 1983
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Measurements of neutral density in ECRH, Ohmically heated and neutral beam heated plasmas on the Heliotron E device are described. Profiles of neutral density determined by the vertically scanned charge exchange neutral flux are compared with the results of the Monte Carlo simulation. In Ohmic and ECRH plasmas, the obtained profiles agree well with the simulation results using Franck-Condon neutral (∼3 eV) as incident particles. In NBI case, the recycling particle with higher energy (typically ∼30 eV) dominates the particle source. The dependence of the neutral density on the average electron density is represented by the parameter I
p. Although the neutral density in Ohmic and ECRH plasmas decreases as \bar
Ne increases, NBI plasma does not have such dependence. The global particle confinement time is estimated, and τ
p decreases as I
p increases.
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Takashi Shimozuma, Takashi Maekawa, Yasushi Terumichi, Shigetoshi Tana ...
1983 Volume 52 Issue 12 Pages
4176-4183
Published: December 15, 1983
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In order to simulate the electron cyclotron heating (ECH) in tokamak plasmas, one-dimensional tokamak transport code is combined with an electron cyclotron wave ray-tracing code, which includes electromagnetic ordinary and extraordinary waves and the mode-converted Bernstein wave. The code is applied to the ECH experiment on the ISX-B tokamak and a fairly good agreement is obtained between the calculation and the experiment. Some heating characteristics of ECH are also examined for both medium size (ISX-B) and small size (WT-2) tokamak parameters. It is revealed that the position of the electron cyclotron resonance layer affects significantly the local heating efficiency.
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Junjiro Kanamori, Makoto Kaburagi
1983 Volume 52 Issue 12 Pages
4184-4191
Published: December 15, 1983
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The ground states of the lattice gas and the equivalent Ising spin system in an external field on the square lattice with the interaction range extending to the third neighbors are rigorously determined for arbitrary values of interaction constants and in the whole range of particle density or external field. The difficulty encountered in the previous analysis made by one of the present authors (M.K.) is removed by deriving two new geometrical inequalities which reflect the lattice geometry of a wider region than the previous ones. The underlying theory is applicable to other cases than the square lattice.
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Hiromi Sakurai, Katsuo Suzuki
1983 Volume 52 Issue 12 Pages
4192-4198
Published: December 15, 1983
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We report the dependence of the ultrasonic attenuation on the temperature, α(
T), in Sb doped Ge over the wide concentration (
N) region 3.2×10
16 to 1.6×10
18 cm
−3 which covers the critical concentration (
Nc=1.5×10
17 cm
−3) for the metal-insulator transition. The results can be classified as follows. In the region 3.2×10
16\lesssim
N<6.9×10
16 cm
−3, the behavior of α(
T) at
T\gtrsim2 K is similar to that observed in a lightly doped sample; in the region 1.3×10
17\lesssim
N\lesssim2.0×10
17 cm
−3, α(
T) has a “shoulder”, which has also been observed in Ge doped
N\gtrsim4×10
17 cm
−3 As impurities by Ishiguro and Mikoshiba, For
N>2×10
17 cm
−3, it is that predicted from a free electron gas model, and we obtained the intervalley scattering time τ
i from α(
T). A discussion on the ultrasonic attenuation in the intermediate concentration region is given.
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Hiromi Sakurai, Katsuo Suzuki
1983 Volume 52 Issue 12 Pages
4199-4205
Published: December 15, 1983
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The stress dependence of the ultrasonic attenuation α(
X) in Sb doped Ge was measured at low temperatures over the wide concentration region 3.3×10
15 to 1.6×10
18 cm
−3. In the intermediate concentration region the behavior of α(
X) at low stresses is different from that observed in the low concentration region except the sample with 3.1×10
16 Sb cm
−3. A simple model is proposed which explains qualitatively the experiment in the lower part of the intermediate region. In the high concentration region a free electron gas model can explain the behavior of α(
X) provided that the existence of a single relaxation time τ is assumed in this system. The values of τ estimated based on this model are consistent with those in the stress free case.
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Hironobu Hyodo, Katsunori Iio, Kazukiyo Nagata
1983 Volume 52 Issue 12 Pages
4206-4212
Published: December 15, 1983
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Birefringence study of the nearest-neighbour spin correlation function was performed on the quadratic layer substitutionally random antiferromagnet K
2Ni
1−xCo
xF
4 (0<
x<1). The system is found to exhibit two-dimensional Ising critical behaviour within the nearly same reduced temperature region as the pure K
2CoF
4. The Néel temperature has a convex dependence on the substitutional concentration
x with a maximum. The phase diagram of this mixture is discussed by introducing a model Hamiltonian.
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Toshiro Fukumoto, Koichi Sano, Shoji Kashida, Hiroyuki Kaga
1983 Volume 52 Issue 12 Pages
4213-4219
Published: December 15, 1983
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The successive structural phase transitions in a linear chain compound (CH
3)
3NHCdCl
3 were studied by means of polarizing-microscopic observations and X-ray and dilatometric measurements.
The sequence of the structural phase transitions of (CH
3)
3NHCdCl
3 was found to be,
(
Remark: Graphics omitted.)
The transition from the (1×\sqrt3) phase to the (2×\sqrt3) phase was reversible, while the transition from the (2×\sqrt3) phase to the (3×3) phase was irreversible. The transition from the (3×3) phase to the (3×2) phase was also reversible.
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Kinshiro Hirakawa, Hideki Yoshizawa, John D. Axe, Gen Shirane
1983 Volume 52 Issue 12 Pages
4220-4230
Published: December 15, 1983
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Spin dynamics of K
2CuF
4 has been studied by neutron scattering technique. The motivation of our study is to make an extention of the previous study by Moussa and Villain, because of the increasing interest in the nature of the transition which might be close to the Kosterlitz-Thouless (KT) type. The wave number dependent magnon frequency and width are systematically measured as a function of temperature and noticiable evolution of wave number dependent dynamics has been observed. In a low wave number region, a steap decrease in magnon frequency was observed at the transition supporting the above conjecture.
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Yoshihiro Ishibashi, Hiroshi Orihara
1983 Volume 52 Issue 12 Pages
4231-4236
Published: December 15, 1983
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The variation of dielectric constant during the course of switching between two states is discussed on the basis of analyses of some simple switching model. When the contribution from boundary area existing between two states is large, the dielectric constant shows a peak.
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O. P. Gupta
1983 Volume 52 Issue 12 Pages
4237-4247
Published: December 15, 1983
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Temperature dependence of the anharmonic Debye-Waller factor for some cubic metals are calculated by employing our recent dynamical model. Willis anharmonic approach has been followed to estimate the effect of anharmonic terms in the crystal potential. A comparative study of the computed values and the experimental data in terms of the Debye-Waller temperature parameter Y and the X-ray Debye temperature
ΘM, reveal the fact that the anharmonic consideration in the crystal potential has greatly improved the results compared with those due to the harmonic and quasi-harmonic approximations.
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Yasuo Y. Suzuki, Takeo Izuyama
1983 Volume 52 Issue 12 Pages
4248-4256
Published: December 15, 1983
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In quantum solids of fermions such as solid
3He, where a tunneling motion for particle exchange is enhanced by zero-point vibrations, there is a possibility that a hybrid of the exchange tunneling and the zero-point vibration may lead to unforeseen magnetic properties, which are outside the scope of the Heisenberg model. The simplest model is adopted for the hybridization. In this model the exchange interactions are assumed to exist only for the nearest neighbor pairs and a pair spin interaction is supposed to grow sufficiently large when the n.n. bond expands in the vibrational motion. The spin-phonon interactions, which are off-diagonal in the phonon representation, are shown to produce remarkable effects on the magnetic field dependence of pressure, on the specific heat, on the susceptibility and on the mechanism leading to exotic spin order such as
uudd.
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Masahiro Inoue, Tadayoshi Kurokawa
1983 Volume 52 Issue 12 Pages
4257-4269
Published: December 15, 1983
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The surface enhanced Raman scattering is studied theoretically for molecules adsorbed on a cylindrical grating. The local field and the Raman light from the adsorbed molecules are treated exactly. A numerical calculation shows that the Raman intensity is enhanced by a factor of 10
3∼10
4 over that from a free molecule for both metallic and dielectric gratings.
The Raman spectrum depends on the emitted phonon mode as well as on the orientation of the adsorbed molecules. Such dependences are illustrated by considering various Raman tensors.
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Akio Yamada, Hirohito Fukutani, Akira Misu
1983 Volume 52 Issue 12 Pages
4270-4276
Published: December 15, 1983
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Piezoreflectivity spectra of KCl are studied by using a uniaxial stress along the [011] direction at room temperature. Two structures are newly observed at about 11.5 and 12.3 eV. In this energy range, a broad reflection band identified with transitions to the second and third lowest conduction bands is known to be located. Trigonal deformation potentials of the two structures are found to be −0.18±0.12 and 0.14±0.07 eV, respectively. From a comparison of these deformation potentials with those of the exciton at the absorption edge and of the core exciton at about 20 eV, it is concluded that the second and third lowest conduction bands are of the
dγ and
dε symmetry.
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Yutaka Unuma, Yasuaki Masumoto, Shigeo Shionoya, Hitoshi Nishimura
1983 Volume 52 Issue 12 Pages
4277-4282
Published: December 15, 1983
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Previously direct measurements of the self-trapping time of 1
s excitons in KI was reported. In this paper, measurements for RbI are described. Picosecond pulses of the fifth harmonic (212.8 nm) of a Nd
3+: YAG laser, which can directly generate the 1
s excitons are used as the excitation source. The rise time of the
Ex luminescence is measured at 4.2 K. From the observed rise time, the self-trapping time is estimated to be 2.0±0.5 ns. The height of the adiabatic potential barrier separating the free and self-trapped exciton states is measured to be 18 and 30 meV for RbI and KI, respectively. The self-trapping time and the barrier height in RbI and KI are compared, and their changes with changing material are discussed on the basis of the theoretical calculation.
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Geeta Ahuja, H. C. Gupta, L. M. Tiwari
1983 Volume 52 Issue 12 Pages
4283-4285
Published: December 15, 1983
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The concentration and the composition dependence of the thermoelectric power in III–V ternary mixed crystals at different temperatures has been investigated. A good agreement with experiment is found in the cases of InP
xAs
1−x, Ga
xIn
1−xAs and InAs
xSb
1−x.
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Akio Enomura, Shin Asai, Yasuhiko Ishiwata, Toshihisa Inabe, Yoshio Sa ...
1983 Volume 52 Issue 12 Pages
4286-4290
Published: December 15, 1983
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Seebeck coefficients of YFe
2O
4.0 and YFe
2O
3.95 were measured from 190 K to 360 K. In YFe
2O
4.0 charge and spin orderings occur and in YFe
2O
3.95 only a spin ordering occurs and thus the effects of orderings on Seebeck coefficient were clearly observed in those oxides. At higher temperatures, coefficients of both specimens become negative and their absolute values increase with temperature as those of Ce
3−xS
4. The data of YFe
2O
4.0 resemble those of Fe
3O
4 below the Verwey transition temperature. The coefficient of YFe
2O
3.95 decreases as the temperature is decreased below the Néel temperature.
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Yoshikazu Hirose, Takashi Tsukahara, Chihiro Hamaguchi
1983 Volume 52 Issue 12 Pages
4291-4299
Published: December 15, 1983
Released on J-STAGE: June 01, 2007
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Investigations of hot electron magnetophonon resonance are carried out in n-Ge at low temperatures (10–20 K) by measuring second derivatives of the longitudinal magnetoconductance with magnetic fields applied in the 〈100〉, 〈110〉 and 〈111〉 directions and new series which have not been observed at high temperatures are resolved for the first time. In addition to the intravalley magnetophonon resonance due to the
Γ-point LO phonons (439 K) intervalley magnetophonon resonance due to the X
1-point (LA, LO) phonons (347 K) and X
3-point TA phonons (116 K) are observed in the three directions. In the case of J//B//〈111〉 impurity magnetophonon series due to the emission of the LO phonons and X
4-point TO phonons (280 K) accompanied by capture of a 1s ground state of donor were detected.
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Yoshikazu Hirose, Takashi Tsukahara, Chihiro Hamaguchi
1983 Volume 52 Issue 12 Pages
4300-4305
Published: December 15, 1983
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Magneto-impurity resonance effect has been investigated in Sb doped n-Ge at low temperatures from 5.2 to 10 K by measuring second derivatives of the magnetoresistance in the longitudinal configuration with J//B//〈100〉, J//B//〈110〉 and J//B//〈111〉. Fourier spectra reveal five peaks for J//B//〈100〉, six peaks for J//B//〈110〉 and four peaks for J//B//〈111〉, which arise from the magnetoimpurity effect, and no magnetophonon resonance was observed in the temperature range. Assignments of the peaks are made by comparing the resonance energies between the observed and calculated values. In addition to the transitions between the 1s and excited states new processes due to the transitions from the excited states to the bottom of the conduction band were observed.
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Fumio Komori, Shun-ichi Kobayashi, Wataru Sasaki
1983 Volume 52 Issue 12 Pages
4306-4310
Published: December 15, 1983
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Inelastic scattering time τ
ε and spin scattering time τ
s are studied in Bi, Cu–Mn alloy and noble metal films through the analyses of their magnetoconductivity. Inelastic scattering time in Bi films is found to be proportional to
T−1 and to the sheet conductivity below 1.5 K, and to depend on
T more strongly at higher temperature. These features are consistent with recent theories on τ
ε due to electron-electron interaction in two-dimensional disordered systems. In Cu–Mn alloy films with various concentration of Mn, systematic change of the magnetoconductivity is mainly ascribed to the variation of τ
s, which is caused by Mn atoms. In noble metal films, the temperature dependence of the magnetoconductivity indicates that both scattering times are of a comparable order of magnitude at low temperature.
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Kazuo Mizuno, Takafumi Aomine
1983 Volume 52 Issue 12 Pages
4311-4317
Published: December 15, 1983
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The temperature
T and perpendicular magnetic field
H dependences of the critical current
Ic have been measured for superconducting wide bridges made of granular aluminum. The measured
T dependence of
Ic near the transition temperature
Tc deviates from that derived from the Ginzburg-Landau (GL) equations in a uniform current distribution. The deviation occurs even under the condition that the self-magnetic field due to the current is negligible, and it increases as the width of bridge or the coherence length increases. These results show that the pair-breaking current density
jc at the edge of bridge is enhanced from
jcGL owing to current concentration due to its geometry. The peak structure with clear hysteresis for the sweep of
H was observed in the
Ic-
H characteristics. The width of the peak seems to be inversely proportional to the bridge width.
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Kazuyoshi Ichinose, Katsuyuki Fujiwara, Hiroshi Yoshie, Hiroyuki Nagai ...
1983 Volume 52 Issue 12 Pages
4318-4322
Published: December 15, 1983
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NMR of
89Y nuclei in Y(Fe
1−xT
x)
2 (T=V, Mn, Co, Ni, Al) has been observed at 4.2 K. Well-resolved satellite structures of Y resonance appear in these compounds. This shows that the Y hyperfine field is mainly due to the magnetic nearest neighbor atoms. The magnetic moment of T atoms is estimated by two methods: (i) the contribution of T atoms to the hyperfine field is proportional to the magnetic moments of Fe and T atoms and (ii) the well known empirical relation between the hyperfine field and the mean magnetic moment of alloys is used. These results are in good agreement with those in dilute T–Fe alloys except for T=Mn.
The intensity ratio of satellite peaks is discussed based upon a statistical distribution of Fe and T atoms.
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Toshio Taniguchi, Hideo Matsuyama, Susumu Chikazawa, Yoshihito Miyako
1983 Volume 52 Issue 12 Pages
4323-4330
Published: December 15, 1983
Released on J-STAGE: May 29, 2007
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Linear, χ
0, and nonlinear, χ
2 and χ
4, susceptibilities were measured in metallic spin glass AuFe. Nonlinear susceptibilities for AuFe (1.5 at.%Fe) diverge at
Tg showing the power law behavior and the critical behaviors around
Tg are interpreted by Suzuki’s theory based on Edwards and Anderson model. The critical exponents γ
s, δ and β were obtained to be γ
s=1.1±0.2, δ=2.0±0.2 and β∼0.9, respectively.
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Jun-ichi Takimoto, Yutaka Toyozawa
1983 Volume 52 Issue 12 Pages
4331-4341
Published: December 15, 1983
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Competition between the electron-electron and the electron-lattice interactions is studied with the 4-site-4-electron model characterized by
B (half of the band width),
U (on-site Coulomb repulsion) and
S (lattice relaxation energy). In the whole range of
B,
U and
S the lowest adiabatic potential is exactly calculated, and all of its minima and their existence conditions are found. The absolute minimum is the antiferromagnetic phase (with antiferromagnetic spin correlation but no lattice distortion) or the charge density wave phase (with alternating lattice distortion). The first-order transition between them occurs along a line close to
U=
S. Electronic and structural properties of these two phases are studied in detail. System size dependence of the phase diagram is discussed, with the emphasis on the difference between 4
n- and (4
n+2)-electron systems.
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Yoshinori Takahashi, Tôru Moriya
1983 Volume 52 Issue 12 Pages
4342-4348
Published: December 15, 1983
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Dynamical properties of spin fluctuations in weakly ferromagnetic metals as calculated by the self-consistent renormalization theory are shown to be consistent with the results of recent neutron scattering experiments on MnSi.
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Makio Kurisu, Hideoki Kadomatsu, Hiroshi Fujiwara
1983 Volume 52 Issue 12 Pages
4349-4355
Published: December 15, 1983
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Electrical resistivity of the cubic CsCl-type ferromagnetic compound CeAg was measured at hydrostatic pressures
p’s up to 18 kbar and in temperatures from 1.6 K to 300 K.
For
p<2.2 kbar, the structural transition temperature from cubic to tetragonal was not accompanied with hysteresis and was pressure independent. For
p≥2.2 kbar, the transition temperature increased largely with
p, accompanied with wide hysteresis. These trends of pressure dependences are discussed based on the Jahn-Teller distortion model in reference to the alloying effect, CeAg
1−xIn
x. The Curie temperature
Tc increased rather rapidly at 2.2 kbar and took a maximum value around 7 kbar. The spin disordered resistivity increased rapidly at 2.2 kbar, but linearly with relatively small gradient above it. The correlation between magnetic and structural transition phenomena are analysed qualitatively, by taking above-mentioned results into account.
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Katsuyasu Kawano, Ryohei Nakata, Minoru Sumita
1983 Volume 52 Issue 12 Pages
4356-4362
Published: December 15, 1983
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The EPR investigations (9.4 and 23.9 GHz) of a copper-adenine complex [Cu(C
5H
4N
5)
2·4H
2O] were made for the interest of the role of a metallic ion in a life. The angular and temperature dependences of the spectra indicated that two Cu
2+ ions, surrounded by four adenine molecules, were strongly coupled through a superexchange interaction. The analyses of the EPR spectra were carried out by a spin Hamiltonian having an exchange term:
Hs=
gβ
HS+
D[
Sz2−1⁄3
S(
S+1)]+
E(
Sx2−
Sy2)+
AIS−
JSISII. The determined parameters for the dimeric Cu
2+ ions are
g⁄⁄=2.24,
g⊥=2.13,
D=−0.10,
E=0.01,
A=0.008 and
J=−200 cm
−1, respectively.
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Masahiko Tokita, Eijiro Haga
1983 Volume 52 Issue 12 Pages
4363-4368
Published: December 15, 1983
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The second-order effect of the quadrupole interaction on the shape of the central line in strained crystals has been investigated on the basis of an analysis of the experimental spin-echo share. With the Gaussian distribution for random field gradients, the following results were obtained: (i) Line shares are similar to the one in the absence of field gradient. When the quadrupole interaction is increased from zero, the line shape is broadened to be observable, and tends to a definite limit rather than to the one with infinite half-width. From the experimental condition, the perturbation treatment is seen to be valid for line shapes near the limit. (ii) The line shape becomes asymmetric. (iii) The resonance-line shift due to the quadrupole interaction is negligibly small in comparison with the observed one. (iv) The asymmetry in field gradients may be neglected for the line shape.
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Minoru Fukui, Ryuji Abe, Kazuaki Tsuchida
1983 Volume 52 Issue 12 Pages
4369-4376
Published: December 15, 1983
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ESR line shapes for the tetrahedra SO
4 in β-K
2SO
4 type crystal with symmetry D
2h16-
Pmcn have been calculated as a function of the direction of the applied magnetic field and the rotation of the tetrahedra in the incommensurate phase. The effect of the one-dimensional incommensurate modulation on the line shape depends strongly on the relative orientation between the magnetic field and the rotation axis of the tetrahedra. The analysis has been applied to ESR spectra of Mn ion in {N(CH
3)
4}
2CoCl
4. The result supports the previous conclusion that the rotational axis of the CoCl
4 tetrahedra is parallel to the travelling direction of the modulation wave.
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