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Michihiro Amenomori, Naoki Hotta, Katsuaki Kasahara, Kohei Mizutani, H ...
1988 Volume 57 Issue 4 Pages
1143-1146
Published: April 15, 1988
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The family events observed at Mt. Fuji were carefully examined to find the anomalously-penetrating showers suggested from the analysis of the data obtained at Mt. Chacaltaya. Our analysis shows that the existence of such anomalous showers beyond fluctuations are not recognized in our family data.
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Mitsuaki Ginoza
1988 Volume 57 Issue 4 Pages
1147-1150
Published: April 15, 1988
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The solution of the Ornstein-Zernike equation is investigated in the modified mean spherical approximation for a binary system consisting of equal-size hard spheres interacting with each other via a pairwise tail potential such as
aiaj\varphi(
r), with
aiaj and \varphi(
r) being the coupling strength between
i- and
j-species of hard spheres and an arbitrary potential function, respectively. For the Bhatia-Thornton partial structure factors
SNN(
q),
SNC(
q) and
SCC(
q), this solution produces a relationship like [
SNN−
S0][
SCC−
c1c2]=
SNC2, where
S0(
q) equals
SNN(
q) at
a1=
a2=0 and
ci is the concentration. It is also shown that this relationship is in reasonably good agreement with the experimental results on thermodynamic properties of liquid Li–Pb alloy.
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Susumu Sasaki, Hiroshi Yasuoka, Tadashi Shimizu, Hironori Nishihara, T ...
1988 Volume 57 Issue 4 Pages
1151-1154
Published: April 15, 1988
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Nuclear spin-lattice relaxation time (
T1) of
139La in the antiferromagnet La
2CuO
4−δ and the superconductor (La
0.9Ca
0.1)
2CuO
4−δ has been measured in a zero applied field and temperature ranges of 1.7 K–299 K and 1.8 K–130 K, respectively. A divergent behavior of the relaxation rate (1⁄
T1) toward the Néel temperature (
TN\simeq250 K) which is characteristic of itinerant antiferromagnets has been observed in La
2CuO
4−δ above
T\simeq70 K. An anomalous enhancement of 1⁄
T1(
T) below about 70 K has been observed in both oxides. Because of this unclarified enhancement, the change of 1⁄
T1(
T) which is associated with the superconducting transition was not observed in (La
0.9Ca
0.1)
2CuO
4−δ below
Tc\simeq18 K.
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Ken-ichi Kumagai, Hiroshi Aoki, Isao Watanabe, Yuki Nakamura, Haruo Na ...
1988 Volume 57 Issue 4 Pages
1155-1158
Published: April 15, 1988
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Nuclear quadrupole resonance (NQR) of
139La in La
2−xBa
xCuO
4 has revealed an unexpected enhancement of nuclear relaxation rates, 1⁄
T1 and 1⁄
T2, with Ba-doping in the low-temperature region, suggesting the occurrence of magnetic instability at
Tc*∼10 K. The remarkable pressure dependence of 1⁄
T1 below
Tc* is sharply in contrast to the pressure independence of 1⁄
T1 above
Tc*. At high pressures, the relaxation rates are remarkably enhanced below
Tc*, increasing proportionally with decreasing temperature.
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Hironori Nishihara, Nobuyuki Sugii, Yoshikazu Hidaka, Migaku Oda, Tada ...
1988 Volume 57 Issue 4 Pages
1159-1162
Published: April 15, 1988
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Zero-field nuclear quadrupole resonance (NQR) spectra of
139La are examined at 1.3 K for single crystals and polycrystals of the antiferromagnetic La
2CuO
4 which have been subject to heat treatments of oxygenation or deoxygenation. Although the Néel temperature (
TN) determined from the static susceptibility strongly depends on the heat treatments, the peak positions of the NQR spectrum at 1.3 K are invariant against the heat treatments for samples with
TN between 135 and 305 K, suggesting that the sublattice moment of the Cu spins at low temperatures is invariant against the heat treatments. A simple oxygen-deficient model described by La
2CuO
4−δ is found to be inadequate from observed effects of the heat treatments on the line widths of the NQR spectrum.
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Hidetoshi Konno, Hideo Soneda
1988 Volume 57 Issue 4 Pages
1163-1166
Published: April 15, 1988
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We studied the chaotic behaviour of soliton-like pulses in a modified Kuramoto-Sivashinsky equation under the influence of an external force η(
t): φ
t+φ
pφ
x+αφ
xx+βφ
xxx+γφ
xxxx+νφ=η(
t). Our findings are as follows: (i) when the equation has the Galilean invariance (
p=1), the external force η(
t) does not promote chaotic behaviour of soliton-like pulses and (ii) when the equation does not have the Galilean invariance (
p=2), irregular creations and annihilations of solitons and holes in the traveling state appear which may be due to the interaction of solitons, holes and radiations.
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Koichi Furutsu
1988 Volume 57 Issue 4 Pages
1167-1172
Published: April 15, 1988
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Probability distributions of irradiance recently proposed by several authors are compared with experimental results of both high-order irradiance moments and log-amplitude variance that are obtained by a simultaneous measurement. In spite of the fact that almost all the distributions show a reasonable agreement with the experimental results of irradiance moments (measured up to the fifth order) within the saturation region at least, the distributions that can give a good fit also to the results of log-amplitude variance are very limited when they are assessed over the range of irradiance variances so far measured. A fundamental reason of this disagreement is discussed. In Appendix, expressions of the moments of both irradiance and log-amplitude truncated at a given level are shown along with a general theory of probability distribution functions with no finite cutoff value.
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Yasuhiro Akutsu, Tetsuo Deguchi, Miki Wadati
1988 Volume 57 Issue 4 Pages
1173-1185
Published: April 15, 1988
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We present a general method to construct link polynomials, invariants for knots and links, from the exactly solvable IRF (Interaction Round a Face) models in statistical mechanics which satisfy the Yang-Baxter relation.
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Katsuya Honda, Hiroyasu Toyoki, Mitsugu Matsushita
1988 Volume 57 Issue 4 Pages
1186-1190
Published: April 15, 1988
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We consider loopless clusters which are restructured repeatedly by diffusive particles released from the cluster itself, being essentially in equilibrium. The resulting clusters are self-similar with fractal dimension
df. By means of the dimensional analysis we give
df={
ds2+2(
dw−1)}⁄{
ds+2(
dw−1)}, where
dw and
ds denote the dimensions of the trajectory of the diffusive particles and of the space in which the cluster is embedded, respectively. The agreement with the numerical result in the case of
ds=
dw=2 obtained by Botet and Jullien is very good. We further make sure our theoretical prediction by simulating the limiting case of
dw=1 (rectilinear trajectory). These constitute a breakthrough that the structure of the cluster in equilibrium can depend on the particle motion
dw, which seems to be irrelevant to pattern formation.
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Toshihiro Kawakatsu, Takashi Matsuda, Akira Ueda
1988 Volume 57 Issue 4 Pages
1191-1198
Published: April 15, 1988
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A one-dimensional propagation of a reaction wave in an exothermically reacting hard disk system is studied using the molecular dynamics method. The structure of the reaction wave has characteristics similar to those of a detonation. Comparison between the results of our computation and those from the hydrodynamic theory is made.
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Kenji Torizuka, Norio Morita, Tatsuo Yajima
1988 Volume 57 Issue 4 Pages
1199-1211
Published: April 15, 1988
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The fluorescence measurement with ultra-short excitation pulses is made to determine the non-Lorentzian shape of the absorption probability in the very far-wing of the sodium D transition collisionally perturbed by rare gas atoms. The absorption probability has been determined in the detuning range from −400 to 1000 cm
−1. A steep decrease of absorption probability in the far blue-wing has first been found. A simplified relation between this far-wing structure and the interatomic potential curves is given theoretically. The maximum of the difference potential between
X2Σ and
B2Σ, which are the unbound states of an exciplex consisting of sodium and rare gas atoms, is determined from our experimental results.
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Reiko Kaname, Yoshiko Ushijima, Mieko Kitsukawa, Masaru Kitaguchi, Tet ...
1988 Volume 57 Issue 4 Pages
1212-1219
Published: April 15, 1988
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Total cross sections σ
t for collisional quenching of H(2s) atoms in H
2, N
2, O
2, CO, CO
2 and CH
4 molecular targets have been measured in the projectile energy range from 0.2 to 3.5 keV. A H(2s) atom beam was produced by using H
+–K near-resonant charge transfer collisions, and σ
t’s were determined with a beam attenuation method. It is demonstrated that, in the lower energy region (<0.5 keV) where the 2s-2p de-excitation process dominates, the long-range interaction due to polarization of a target molecule is more important than that due to its permanent quadrupole moment
M2. This result is not consistent with theoretical treatments where
M2 is assumed to be more effective than the polarization. In the higher energy region (\gtrsim0.5 keV), the σ
t curves behave in complex manners due to opening of other quenching processes such as electron-loss and electron-capture processes.
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Seiji Tsurubuchi, Tatsuo Arikawa
1988 Volume 57 Issue 4 Pages
1220-1225
Published: April 15, 1988
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Total excitation cross sections for the magnetic sublevels of the 2
p state of Li have been measured in Li
+ collisions with Ar and Kr atoms in the energy range between 0.4 to 4.0 keV by means of an optical spectroscopic technique. It was found that the energy dependence of the cross sections as well as their magnitude is very similar between Ar and Kr targets. Excitation processes are discussed on the basis of the promotion model based on the state diabatic correlation diagrams.
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Kenji Inoue
1988 Volume 57 Issue 4 Pages
1226-1237
Published: April 15, 1988
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Nonlinear oscillation described by the equation, \ddot
x+sin
x+(ε
1+ε
2cos
x)\dot
x=0, is considered. By applying Hori’s general perturbation theory for non-canonical system, a necessary condition for the existence of limit cycles is given in terms of ε
1 and ε
2, and analytical expressions for limit cycles are obtained up to the first order. The analytical approximate solutions are compared with numerical solutions and satisfactory agreement between them is observed.
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Takayuki Morishita, Atsushi Fukuyama, Yoichiro Furutani
1988 Volume 57 Issue 4 Pages
1238-1254
Published: April 15, 1988
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Ion cyclotron range of frequencies (ICRF) heating in the two-ion hybrid resonance regime is numerically studied and the results are compared with those of the heating experiments on the JET tokamak. The kinetic one-dimensional analysis of the ICRF wave is coupled with the anisotropic Fokker-Planck equation and the one-dimensional transport code, Spatial transport coefficients are inferred from those of the drift wave model and a phenomenological internal disruption is introduced. Calculated power deposition profiles agree well with experimental results. Degradation of confinement with increasing heating power, profile modification due to the off-axis heatinq and heat pulse propagation after the internal disruption are well reproduced by our simulation model.
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Sigeo Hamada, Marilia Tavares Azevedo
1988 Volume 57 Issue 4 Pages
1255-1268
Published: April 15, 1988
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Further study of a model in which decay of the magnetic flux is taken into account has been made following other authors’ works. Contrary to a current speculation, the lhd anomaly decreases the flux loss time
tφ even in its order of magnitude, as well as the particle loss
tN. The physical reason is discussed in the text. For various sets of given parameters in computation, the model is compared with published data of FRX-C experiments in Los Alamos and it is concluded that levels of the lhd anomaly are too low by two or three orders of magnitude to explain the observed
tφ and
tN simultaneously. An assumption of uniform resistivity leads to rather good agreement with experiments: the lhd anomaly is overwhelmed by a roughly uniform anomaly due to unknown causes.
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Kimitaka Itoh, Sanae-Inoue Itoh
1988 Volume 57 Issue 4 Pages
1269-1272
Published: April 15, 1988
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Detached and attached plasmas in stellarators are studied. The energy balance equation in the peripheral plasma is solved by use of a simple model of the radiation loss. Criterion for the detached/attached plasma is obtained. The relation with the density limit is also discussed.
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Yoshihide Honda, Yushi Kato, Norio Satomi, Masahiro Nishikawa, Kenji W ...
1988 Volume 57 Issue 4 Pages
1273-1280
Published: April 15, 1988
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In the CTCC-I experiment, the instability appears in almost all the discharges and occurs several times in the every discharge. The dominant toroidal mode number for this instability is the
n=2, which is measured using a toroidally arrayed magnetic probe. This mode shows different behavior in the instabilities; in the earlier and intermediate phase of the discharge the saturation phase come to appear, but near the termination this saturation phase does not appear. These phenomena probably depend on the magnetic Reynolds number. The evolution of the magnetic field configuration is also investigated. From these results, the instability observed in the CTCC-I spheromak is found to be the
n=2 ideal kink mode.
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Hiroyuki Mori, Hiizu Nakanishi
1988 Volume 57 Issue 4 Pages
1281-1286
Published: April 15, 1988
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We demonstrate that a topologically non-trivial point defect can be energetically unstable against expanding into a ring defect by taking nematic liquid crystal as an example.
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Takanori Fukami
1988 Volume 57 Issue 4 Pages
1287-1290
Published: April 15, 1988
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The crystal structure of 97% deuterated ammonium dihydrogen phosphate (DADP) is analyzed in the antiferroelectric (AFE) phase. Comparing the AFE distortion of PO
4 tetrahedrons and the change of the position of the N atom at the phase transition temperature (
Tc) in DADP with those in ADP, the author found that the distortion and the change of the position are larger in DADP than in ADP. This is consistent with the conclusion obtained by the electron spin resonance (ESR) study. In the AFE phase the AFE distortion of PO
4 tetrahedrons and the position of the N atom do not depend on temperature remarkably. These do not agree with the ESR data.
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Mitsuo Machida, Toshirou Yagi
1988 Volume 57 Issue 4 Pages
1291-1302
Published: April 15, 1988
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The absolute crystal structure of the deuterated dicalcium strontium propionate (DDSP) has been determined by the X-ray diffraction with a four-circle automatic diffractometer at three temperatures in each of the paraelectric and ferroelectric phases. The space group is determined to be D
44-P4
12
12 or D
48-P4
32
12 in the paraelectric phase with the
R-factors less than 3% and to be C
42-P4
1 or C
44-P4
3 in the ferroelectric phase with the
R-factors less than 5%. The molecular structure of the deuterated propionates is also elucidated and compared with that of the nondeuterated one. The comparison confirms the structure quite similar to each other, indicating no isotope effect on the molecular structure. The disordered arrangement of the propionate molecules on (001) plane is observed in the ferroelectric phase similarly to the nondeuterated DSP.
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Yasusada Yamada, Yukio Noda
1988 Volume 57 Issue 4 Pages
1303-1307
Published: April 15, 1988
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The crystal structure of ζ-phase AgZn has been reconsidered. It is shown that the static structure of ζ-AgZn is expressible in terms of (i) two types of lattice waves (phonon modes) and (ii) one type of probability density wave of Zn atom site-occupation. It is noted that the relevant phonon modes are the soft modes existing commonly in
bcc Hume-Rothery alloys. It is pointed out that ζ-AgZn shares the common origin of stabilization with 9
R martensites and ω-phase.
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Masayuki Hasegawa, Masatoshi Moriyama, Mitsuo Watabe, W. H. Young
1988 Volume 57 Issue 4 Pages
1308-1320
Published: April 15, 1988
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First-principles pseudopotentials of the hcp divalent metals are constructed following the method proposed by Hasegawa and Watabe (J. Phys. C (Solid St. Phys.)
16 (1983) L29). These pseudopotentials have several practical advantages: They are energy-independent and expressed in terms of simple analytic functions. These pseudopotentials are used in the second-order perturbation calculations for primarily predicting stable crystal structures. The predicted axial ratios
c⁄
a of the hcp structure are 1.793 and 1.725 for Zn and Cd respectively at the densities observed at 0 K, being in reasonable agreement with experiment especially for Zn. The results of calculations for Mg, which has essentially an ideal
c⁄
a ratio, are also presented for comparisons.
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Yoshimasa Hayashi, Masaru Kasahara, Masaharu Tokunaga, Itaru Tatsuzaki
1988 Volume 57 Issue 4 Pages
1321-1326
Published: April 15, 1988
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Raman scattering spectra of internal modes have been studied in antiferroelectric NH
4H
2AsO
4 at several temperatures near the transition temperature
TN. The evidence of the C
1 local site symmetry of H
2AsO
4− in the paraelectric phase has not been obtained even just above
TN. The integrated intensity of the ν
2 mode giving the justification of the C
1 symmetry in the antiferroelectric phase increases with decreasing temperature below
TN. In addition, the linewidth of the ν
1 internal mode increases with increasing temperature. From the latter two results, the relaxation of the rigid ice constraint is proposed in the discussion of the models of the phase transition in hydrogen bonded antiferroelectrics.
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Yuhei Mori
1988 Volume 57 Issue 4 Pages
1327-1340
Published: April 15, 1988
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Frequencies of the localized modes around a soliton are calculated for finite length C
nH
n+2+, C
nH
n+2−, C
nD
n+2+ and C
nD
n+2− (
n odd). The molecular orbital method and three dimensional normal coordinate analysis are used. The frequency of the C–C stretching translational mode (T) is significantly affected by the chain length for both isotopes. For C
nD
n+2+, this mode couples with the C–D bending translational mode (TH). This coupling is seen clearly in the displacement vectors. The coupling explains well the two broad peaks in the i.r. spectrum if the chain lengths have a distribution around
n\simeq13∼21. It is also found that dopant pinning has similar effects to chain shortening; namely, reducing the soliton width, raising the frequency of the T mode, and causing coupling of the T and TH modes. The effective mass of a soliton is found to have the same value in C
nH
n+2+, C
nH
n+2−, C
nD
n+2+ and C
nD
n+2−.
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Motoyuki Nomura, Saiko Negishi, Yoji Okano, Hiroshi Fujiwara
1988 Volume 57 Issue 4 Pages
1341-1343
Published: April 15, 1988
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The fracture plane of potassium iodide which experienced the phase transition at high pressure was observed with the stereoscopic microscope at zero pressure, where the pressure was applied in the controlled rate and removed rapidly in various time intervals,
Δt’s, after the initiation of the phase transition was detected. The outer region of the fracture plane observed, domain B, was bumpy and random, suggesting that this region experienced the phase transition. However, the inner region of the fracture plane, domain F, was smooth, flat and considerably cleavable, indicating that this domain remained almostly at B1 in the case of very small
Δt. Although increasing
Δt did not alter the geometrical appearance of the fracture plane, the cleavability in phase F was rather lost, which leads us to the conclusion that the transition following the formation of domain B proceeded over the entire volume of domain F.
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Hidetsugu Kitatani, Takehiko Oguchi
1988 Volume 57 Issue 4 Pages
1344-1351
Published: April 15, 1988
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An antiferromagnetic triangular Ising model with ferromagnetic next nearest neighbor interactions is studied by means of a transfer matrix method and a finite size scaling. Using the Roomany-Wyld approximation, it cannot be concluded definitely whether the system has only one critical point or not. By studying decays of the correlation functions of each sublattice, it is found that there is a finite temperature region where the correlation functions of each sublattice show a power law decay, namely, in this region every temperature is a critical temperature. The results by means of the present transfer matrix method are in good agreement with that by Monte Carlo methods, namely, the discrepancy between both results, reported recently, can be got rid of.
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Naoki Yamamoto, Kazuya Tsuda, Katsumichi Yagi
1988 Volume 57 Issue 4 Pages
1352-1364
Published: April 15, 1988
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The modulated structure in the incommensurate phase of quartz was studied by high voltage electron microscopy. The modulation was found to be due to formation of triangular microdomains of the Dauphiné twins. In addition to the well known Dauphiné twin relation we found that at the Dauphiné twin boundaries there exist lattice displacement parallel to the boundaries. The significant relations among the atom arrangements in neighboring domains, the lattice displacement and the orientation of the Dauphiné twin boundary were deduced, which determine a domain configuration in the modulated structure. Our observations indicate that the modulated structure is formed by freezing of the two kinds of atomic displacement which correspond to the B
1 type optic phonon mode and transverse accoustic (TA) phonon mode on the
Σ line.
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Hisashi Hiramoto, Shuji Abe
1988 Volume 57 Issue 4 Pages
1365-1371
Published: April 15, 1988
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The dynamics of an electron in a one-dimensional tight-binding model with incommensurate sinusoidal modulation (Harper’s model) is studied numerically. The width of a wavepacket of an electron put on a single site at the time
t=0 exhibits such asymptotic time evolution as \sqrt〈
Δx2〉∼
tα, where the dynamical index α takes only three values: α=1 for
V<
Vc, α=0 for
V>
Vc and α=α
c (a value near 1/2) for
V=
Vc, where
V is the strength of modulation and
Vc is the critical value. This behavior is in a striking contrast with that in Fibonacci chains, in which α can take any value between 0 and 1 depending on the modulation strength as shown in our preceding paper [J. Phys. Soc. Jpn.
57 (1988) 230].
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Morio Suzuki, Shuzo Kawata, Shigenori Ichinose
1988 Volume 57 Issue 4 Pages
1372-1376
Published: April 15, 1988
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The zero-bias anomaly in the tunnel conductance
G(
V,
H) characteristics of Pb-SiO
1+x-InSb junctions was investigated under zero and 37.2 kOe magnetic fields at 4.4 K for the junction fabricated on n-InSb (
n=8.14×10
16 cm
−3) and under magnetic fields from 0 to 31.0 kOe at 4.2 K for the junction fabricated on p-InSb (
p=2.65×10
16 cm
−3). The
G(
V,
H) was almost independent of the magnetic field for the junction fabricated on n-InSb. For the junction fabricated on p-InSb, the magnetic field dependence of differential resistance
R(0,
H)=1⁄
G(0,
H) was found to obey the relation ln
R(0,
H)∝
H. Taking into account the shrinkage of hole orbit in localized states with the magnetic field, we can explain the behavior by the variable-range hopping assisted tunneling.
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Masahiko Takahashi, Hideyuki Tanaka, Takeo Satoh, Masahumi Kohgi, Yosh ...
1988 Volume 57 Issue 4 Pages
1377-1383
Published: April 15, 1988
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A single crystalline CeGa
2 was obtained by floating-zone technique. Electrical resistivity data showed no Kondo like behavior. Specific heat measurements revealed successive phase transitions at around 10 K. Magnetic measurements showed that these are related with various magnetic states of CeGa
2. The lowest temperature phase was ferromagnetic and the magnetic phase diagram with respect to temperature and magnetic field was proposed.
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Nobuya Sato, Hiroshi Mori, Takeo Satoh, Tsuneo Miura, Humihiko Takei
1988 Volume 57 Issue 4 Pages
1384-1394
Published: April 15, 1988
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Single crystals of the ferromagnetic dense Kondo system CeSi
x were grown, and the specific heat, the electrical resistivity and the magnetic susceptibility were measured. Electrical resistivity measurements clearly show the typical Kondo behavior, which unambiguously tells that CeSi
x is a ferromagnetic dense Kondo system. The appreciable anisotropy of the magnetic susceptibility is analyzed with the crystalline field effect and a conjecture is made that the ground doublet is a
Γ7-like doublet.
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Kenji Sumiyama, Yasuhiro Kawawake, Yoji Nakamura
1988 Volume 57 Issue 4 Pages
1395-1401
Published: April 15, 1988
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Magnetization and Mössbauer effect have been measured for bcc, fcc and amorphous Fe
1−y(Cu
1−xAg
x)
y alloys sputter-deposited on liquid nitrogen cooled substrates. These alloys are ferromagnetic at low temperatures. In the fcc Fe
1−y(Cu
1−xAg
x)
y alloys with
y=0.65 and 0.85, the magnetic moment of Fe atoms and the magnetic hyperfine field of
57Fe nuclei increase with the increase in
x. The substitution of Ag atoms with a large atomic size for Cu atoms increases the atomic volume of Fe atoms, leading to a larger magnetic moment of Fe atoms as well as a larger magnetic hyperfine field. The magnetic and Mössbauer characteristics of the amorphous alloys are similar to those of the fcc alloys with the proximate concentrations.
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Satoru Maegawa, Takao Goto, Yoshitami Ajiro
1988 Volume 57 Issue 4 Pages
1402-1411
Published: April 15, 1988
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The successive magnetic phase transitions (
TN1 and
TN2) and magnetic properties of CsNiCl
3, a Heisenberg antiferromagnet on the triangular lattice, have been investigated by means of the nuclear magnetic resonance of
133Cs. In the low temperature phase (
T<
TN2), the 120° structure of Ni
2+ spins was confirmed by the angular dependence of NMR spectra. In the intermediate phase (
TN2<
T<
TN1), the observed angular dependences of NMR spectra can not be explained by the simple component disorder model which has been proposed previously. We interpret the NMR results in the intermediate phase by the component disorder model with the quasi-degeneracy. It was found that the quasi-degeneracy due to the freedom of rotation of the 120° spin structure in the
ac-plane survives beyond
TN2 down to about 3 K.
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Masafumi Sera, Noriaki Sato, Tadao Kasuya
1988 Volume 57 Issue 4 Pages
1412-1423
Published: April 15, 1988
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The thermal expansions and magnetostrictions of Ce
xLa
1−xB
6 (
x=1.0, 0.5 and 0.25) single crystals in both longitudinal and transverse magnetic fields up to 80 kOe have been performed in the temperature range from 1.39 K and ∼20 K. In the paramagnetic region, the results show the systematic but drastic variations with increasing Ce concentration indicating the importance of the interaction between Ce ions. The magnetic field induced enhancement of the crystal volume shrinkage observed in Phase II indicates that the antiferro-quadrupolar ordering has a magnetic field induced character. The anisotropic expansion of the crystal volume was observed in the single domain state in Phase III.
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Kiyohide Nomura, Minoru Takahashi
1988 Volume 57 Issue 4 Pages
1424-1427
Published: April 15, 1988
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The cluster spin decomposition is applied to the projector Monte Carlo simulation. We investigate the ground state energy and transverse correlation functions of one dimensional
XY model. We enlarge the size of cluster up to nine. For fairly large τ, the agreement of Monte Carlo data with exact results is very good.
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Taturu Yosida, Makoto Morita, Muneyuki Date
1988 Volume 57 Issue 4 Pages
1428-1434
Published: April 15, 1988
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Magnetizations of two trinuclear chromium salts are measured in pulsed magnetic fields up to 350 kOe. The experiment is done below 1 K using a
3He cryostat arranged in a large-bore magnet of 6 cm in diameter. In Cr-propionate, the ground state crossover from
S=1⁄2 to
S=3⁄2 is observed at 272 kOe as a stepwise increase in the magnetization curve. The measurement in Cr-acetate at 0.6 K shows that the increase consists of two steps at 276 kOe and 314 kOe corresponding to two inequivalent sites of magnetic trimers in this compound. The magnitudes of the intra- and inter-trimer exchange interactions are discussed.
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Satoru Inagaki, Hidetoshi Fukuyama
1988 Volume 57 Issue 4 Pages
1435-1441
Published: April 15, 1988
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The transition temperatures
TSP and
TN of the paramagnetic state to the spin-Peierls state and to the Néel state are derived on the basis of the phase Hamiltonian, which takes proper account of the quantum nature of the quasi-one-dimensional Heisenberg antiferromagnet coupled with the lattice distortion. The expressions of
TSP and
TN are essentially the same as those obtained by Cross and Fisher and by Fowler. The tendency of the competition betweern the spin-Peierls state and the Néel state for
Tc is in accordance with the phase diagram of the ground state obtained previously.
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Masahiro Matsumura, Hideki Yamagata
1988 Volume 57 Issue 4 Pages
1442-1448
Published: April 15, 1988
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The distribution of the hyperfine field at
27Al in Fe
0.695Al
0.305 alloy in thermal equilibrium state at various annealing temperature,
Ta was measured to study microscopically the phase transition from B2 to DO
3 in the
reentrant spin glass composition in FeAl alloy system. At the B2 phase, the simple broad spectrum is observed. When
Ta is reduced and enters to DO
3 region, the spectrum separates roughly to two groups. One has a peak at about 55 MHz (Sig.H) and the other has a peak at about 30 MHz (Sig.L). Sig.L increases rapidly and, at the same time, Sig.H decreases with decreasing
Ta without shifting the peak positions. The results directly show that the phase transition occurs heterogeneous way as that DO
3 region expands at the expense of B2 region. The coexistence is still observed at sufficiently low
Ta. The coexistence is inevitable in this non-stoichiometric composition.
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Yoshiaki Chiba, Naoto Kontani, Muneyuki Date
1988 Volume 57 Issue 4 Pages
1449-1455
Published: April 15, 1988
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Spin-lattice relaxation times of Co
2+ spins in yttrium aluminum garnet (YAG) are investigated below 100 K. Co
2+ impurities in YAG have the octahedral, tetrahedral and interstitial sites and these spins have considerably different local crystalline electric field symmetries and intensities. The observed relaxation times well reflect the local fields and it is found that the octahedral and interstitial spins show the Orbach relaxation process with the energy gap
Δ⁄
k of 280 K and 95 K, respectively, while the tetrahedral spin shows simple direct- and Raman-processes.
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Shigeru Takagi, Akira Oyamada, Tadao Kasuya
1988 Volume 57 Issue 4 Pages
1456-1465
Published: April 15, 1988
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The microscopic magnetic properties of the heavy-electron compound YbP have been investigated by
31P NMR at temperatures from 0.38 to 600 K. The observations of both an abrupt decrease of 1⁄
T1 at around 0.7 K and additional broadening of the spectrum below this temperature show that YbP orders magnetically at low temperatures. In the paramagnetic state, the Knight shift vs susceptibility plot exhibits a marked change of the slope at around 100 K with a larger hyperfine coupling constant of −4.02 kOe/μ
B below 100 K. Based on a semimetallic band structure of the compound, a simple model is presented, in which the previously observed anomalous broad maximum in the low-temperature specific heat is ascribed to the Kondo effect due to a large mixing between a
Γ6 ground state of 4f hole of Yb
3+ ion and occupied P-derived 3p states in the valence bands. The contribution of this p-f mixing mechanism to the transferred hyperfine interaction is also evaluated.
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Fuminao Shimizu, Haruhiko Suzuki, Toshihisa Yamaguchi, Shozo Sawada
1988 Volume 57 Issue 4 Pages
1466-1468
Published: April 15, 1988
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Phase transition temperatures of single crystals of Rb
2CoCl
4 prepared by the Bridgman method were checked by a DTA technique and a dielectric measurement and it was found that the Curie temperature
TC is −74°C and the normal-incommensurate transition point
Ti is 21°C on heating. The thermal anomaly at the Curie temperature
TC was observed by the DTA technique with a Ge–Ag thermocouple. The temperature dependence of the dielectric constants in the
b and
c directions was measured in a temperature range covering these phase transition points and the temperature dependence of
Ps and
Ec was determined from the observed 50 Hz
D-
E hysteresis loop, respectively. It was determined that the ferroelectric axis of Rb
2CoCl
4 is the
a axis in reality.
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Ikuo Yamamoto, Shunsuke Hirotsu
1988 Volume 57 Issue 4 Pages
1469-1477
Published: April 15, 1988
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The effect of random interaction among dipolar impurities on the dielectric properties of doped alkali halide KI
1−x(NO
2)
x was investigated through the dielectric measurement. The dielectric constant shows a maximum at a temperature
TF, which depends on both the measuring frequency and the NO
2 concentration
x. The dielectric dispersion data represented in the conventional. Cole-Cole plot show characteristic asymmetry, and the data having the same value of
T⁄
x fall on a universal curve. These features of the obtained Cole-Cole plot agree qualitatively with theoretical predictions based on a Glauber model with random dipole-dipole interaction.
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Kazutoshi Yagi, Masabumi Miyabe, Akio Yamada, Yoshihiro Aiura, Hirohit ...
1988 Volume 57 Issue 4 Pages
1478-1488
Published: April 15, 1988
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Piezoreflectance spectra of rubidium chloride were measured in the photon energy range from 6 to 30 eV at about 120 K. For the structure at 9.01 eV, cubic piezoreflectivity spectrum do not have line shape proportional to that of the logarithmic energy derivative of reflectivity spectrum, and both of tetragonal and trigonal responses on piezoreflectivity were observed. We ascribed it to a composite of the
L and
X excitons. The piezoreflectance responses of the core excitons located between 15 and 18.5 eV are interpreted well by the localized excitation model by Satoko and Sugano.
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Michio Niwano, Shigeru Sato, Tsuneharu Koide, Tetsuo Shidara, Atsushi ...
1988 Volume 57 Issue 4 Pages
1489-1496
Published: April 15, 1988
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Optical reflectance spectra of CeO
2 crystal have been measured in the photon energy range from 2.5 to 40 eV. A Kramers-Kronig analysis of the reflectance data has been performed to obtain the dielectric function and related functions. The observed spectral features can be explained in terms of the charge transfer and interband transitions and the atomic-like excitation of the Ce 5
p core electron. A peak regarded as a candidate for the “4
f2” feature has been observed at an excitation energy of 13 eV.
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Tohru Sugimoto, Etsuro Ito, Hideo Suzuki
1988 Volume 57 Issue 4 Pages
1497-1507
Published: April 15, 1988
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We consider retinal and its related compounds in planar configuration provided they have no ionic structure, and we extend the ordinary INDO–CI method to calculate their bond lengths in consistence with their electronic states. One of the important features of our extended INDO–CI method is that each bond length is calculated as a function of bond order which is similar to the Coulson type of relation derived by the π-electron approximation. The extended INDO–CI calculations of the bond lengths, electronic structure and optical absorptions of the molecules indicate that the previous results, which were obtained by Suzuki
et al. using the π-electron approximation, are reasonable.
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Seizo Watarai, Akira Nakanishi
1988 Volume 57 Issue 4 Pages
1508-1509
Published: April 15, 1988
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