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Tetsuo Deguchi, Kyoichi Tsurusaki
1993 Volume 62 Issue 5 Pages
1411-1414
Published: May 15, 1993
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We investigate the topology of random walks using derivatives of the Jones polynomial. We enumerate formation probabilities of nontrivial knots 3
1, 4
1, 5
1 and 5
2 in closed Gaussian random walks.
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Hidezumi Terazawa
1993 Volume 62 Issue 5 Pages
1415-1417
Published: May 15, 1993
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Although the most likely explanation for two abnormal events with the charge of
Z=14 and the mass number of
A≅370 recently observed in cosmic rays is that they are super-hypernuclei (or strange quark matter) as claimed, the second most likely interpretation is that they are “technibaryonic nuclei” or “technibaryon-nucleus atoms”. The distinction between a super-hypernucleus and a technibaryonic nucleus or a technibaryon-nucleus atom for future experiments is discussed in some detail.
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A. K. T. Assis
1993 Volume 62 Issue 5 Pages
1418-1422
Published: May 15, 1993
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We calculate utilizing Weber’s law the force on a moving charge exerted by a stationary charged spherical shell surrounding it. We obtain a net force different from zero which is proportional to the acceleration of the test particle relative to the spherical shell. This result can be interpreted by saying that the inertial mass of a test particle should change if it is placed inside a charged spherical shell. We conclude that this modification in the inertial mass is proportional to the electrostatic potential of the charged spherical shell and to the electric charge of the test particle. Then we present some possible experiments which could be performed to test this prediction.
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Yoshiko Miyamoto, Mikio Shindo
1993 Volume 62 Issue 5 Pages
1423-1426
Published: May 15, 1993
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The magnetoelectric (ME) effect was measured for a single crystal of magnetite below 30 K by means of an alternating current (AC) method. The ME domains were controlled through uniaxial mechanical stress together with a magnetic and an electric field. The ME polarization parallel to the
b axis induced by rotating the DC magnetic field in the
ac plane was successfully reversed upon reversing the electric field applied parallel to the
b axis. This is direct evidence that the spontaneous electric polarization has the
b axis component, and consequently, the
ac mirror plane does not exist.
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Yoshiyuki Harada, Tyuzi Ohyama, Eizo Otsuka, Kohji Tashiro, Masamichi ...
1993 Volume 62 Issue 5 Pages
1427-1430
Published: May 15, 1993
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Temperature dependence of Fourier-Transform Infrared (FTIR) spectra of C
60 has been measured in a temperature range of 100–315 K. The half-width, integrated intensity and peak frequency of the absorption bands have been found to change markedly in the phase transition temperature regions of 250 and 190 K. These results are discussed in connection with change in mobility of C
60 molecules as well as in structure of the unit cell.
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Shigeru Takagi
1993 Volume 62 Issue 5 Pages
1431-1435
Published: May 15, 1993
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New systematics of U-based metallic compounds is proposed in terms of the radius of the U ion, or equivalently, the
relative interatomic distance between U and ligand atoms,
evaluated with reference to the corresponding isomorphous rare-earth compounds, and the widely varying physical properties of these compounds are discussed in view of this systematics.
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Hidetoshi Fukuyama
1993 Volume 62 Issue 5 Pages
1436-1438
Published: May 15, 1993
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It is proposed that the reentrant metallic state in (R-DCNQI)
2Cu results from the crossover between classical and quantum regimes of the tunneling processes of the rotational motions of radicals,
R, which can either be CH
3 or CH
3O.
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Hidenori Goto, Shingo Katsumoto, Shun-ichi Kobayashi
1993 Volume 62 Issue 5 Pages
1439-1441
Published: May 15, 1993
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We measured the
63Cu nuclear relaxation rate in Cu–Mn and Cu–Au fine particles having a mean diameter of 60 Å. We found that the suppression of the rate due to level quantization of conduction electrons is eliminated by spin scattering resulting from Mn impurities, while it is not affected by spin-orbit scattering resulting from Au impurities.
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Yoshiya Homma, Kenji Sumiyama, Hiroshi Yamauchi, Kenji Suzuki
1993 Volume 62 Issue 5 Pages
1442-1445
Published: May 15, 1993
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In an amorphous Ce-42 at%Ru alloy produced by sputtering, the electronic specific heat coefficient rapidly increases with decreasing temperature,
T, below 5 K. The magnetic susceptibility obeys the Curie-Weiss law above 100 K; it is enhanced below 100 K and saturated below 6 K. The electrical resistivity, ρ, is large due to disorder scattering. With decreasing
T, ρ increases for
T>40 K, showing −log
T dependence (the incoherent Kondo effect) and decreases for
T<40 K (the coherent Kondo effect). The 4f electrons strongly correlate with the conduction electrons to form the singlet Fermi liquid state even in the random alloy.
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Hiroyuki Nakamura, Kazuhiro Ito, Akihiro Uenishi, Hirofumi Wada, Masay ...
1993 Volume 62 Issue 5 Pages
1446-1449
Published: May 15, 1993
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The magnetic susceptibility, electrical resistivity and low-temperature specific heat have been measured for a ternary compound YInCu
4 which forms the cubic C15b-type crystal structure. YInCu
4 is diamagnetic, which is probably due to the low density of conduction electrons. With decreasing temperature, the electrical resistivity increases to a broad maximum around 300 K and then decreases gradually to the lowest temperature. The temperature dependence of
C⁄
T, where
C is the specific heat, is convex downward over the entire temperature range of measurement to 1.5 K. YInCu
4 may be classified as a semimetal. The origin of the transport and thermal anomalies may be explained in the framework of semimetallic substances.
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Yoshiaki Saito, Koichiro Inomata, Atsushi Goto, Hiroshi Yasuoka
1993 Volume 62 Issue 5 Pages
1450-1454
Published: May 15, 1993
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Co/Cu superlattices were prepared by changing the Ar acceleration voltage (
VB) in ion beam sputtering.
VB dependence on the nanostructure of the interface alloy regions has been deduced from the
59Co nuclear magnetic resonance (NMR) spin-echo spectrum, and the correlation between the magnetoresistance (MR) ratio and interface structure was investigated. The results have shown that there is a correlation between the interlayer interaction and the interface chemical structure. The Co average fractions in the interface alloy regions are nearly uniform and equal to 50 at.% for superlattices having small
Δρ, and distributed for superlattices having large
Δρ. Moreover, the local strain from the shift in the hyperfine field has been found to be correlated with the Co uniaxial anisotropy constant due to the strain from the epitaxial growth on Cu.
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Tetsufumi Tanamoto, Hiroshi Kohno, Hidetoshi Fukuyama
1993 Volume 62 Issue 5 Pages
1455-1458
Published: May 15, 1993
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Dynamical spin susceptibility, χ(
q, ω), of the
t-
J model with transfer integrals of the extended spatial range has been evaluated based on the slave-boson mean-field theory for both LSCO- and YBCO-type Fermi surfaces. In the former, the width and height of the incommensurate (IC) peaks are seen to have strong dependences on ω and the temperature,
T. Interestingly, and in agreement with experiments, the IC peaks at low energy become sharper in the singlet RVB state which, in our classification, corresponds to the superconducting state in the region of optimal doping. In the case of YBCO, the dependences on ω and
T at
q=
Q≡(π, π), the antiferromagnetic wave vector, have particular features which share common qualitative characteristics with the experimental findings.
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Seiji Miyashita, Shoji Yamamoto
1993 Volume 62 Issue 5 Pages
1459-1462
Published: May 15, 1993
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Thermodynamic properties of
S=1 antiferromagnetic Heisenberg chains with free and periodic boundaries are investigated by means of a quantum Monte Carlo method. The specific heat is shown to have a peak at a temperature
Tpeak∼2
Δ, where
Δ is the energy gap of the present model, although global shape of the temperature dependence is very similar to the Schottky type specific heat. In open chains, due to the four-fold degeneracy of the ground state, the magnetic susceptibility shows a Curie-like divergence regardless of the number of spins. The extracted diverging part is consistent with the edge moment
S=1⁄2.
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Kazuo Hida
1993 Volume 62 Issue 5 Pages
1463-1465
Published: May 15, 1993
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The ground state of the alternating spin-1/2 Heisenberg chain is studied with anisotropy on the antiferromagnetic bond. This model reduces to the spin-1 XXZ chain if the isotropic bond is ferromagnetic and infinitely strong. The ground-state phase diagram is determined by the numerical diagonalization of finite-size systems. The results are consistent with the series expansion results by Yamanaka, Hatsugai and Kohmoto, and confirms the qualitative phase diagram predicted by Kohmoto and Tasaki.
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Kazuo Hida
1993 Volume 62 Issue 5 Pages
1466-1469
Published: May 15, 1993
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The critical exponents of the phase transitions in the ground state of the ferromagnetic-antiferromagnetic alternating spin-1/2 Heisenberg chain are determined by means of the numerical diagonalization with emphasis on the boundary between the Haldane phase and the large-
D phase. It is found that this phase boundary is a line of continuously varying critical exponents. The results are in agreement with the series expansion results by Yamanaka, Hatsugai and Kohmoto.
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Masafumi Tamura, Hiroshi Sawa, Shuji Aonuma, Reizo Kato, Minoru Kinosh ...
1993 Volume 62 Issue 5 Pages
1470-1473
Published: May 15, 1993
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Magnetization measurement for oriented single crystals of (DMe-DCNQI-
d8)
2Cu (DMe-DCNQI=2,5-dimethyl-
N,
N′-dicyanoquinonediimine) revealed weak ferromagnetism with spontaneous magnetization perpendicular to the
c-axis below 8 K. From the anisotropy of magnetic susceptibility and spin-flop-type magnetization curve at 1.8 K, the
c-axis is found to be the hard axis in the antiferromagnetic state.
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Hideki Tou, Masahiro Matsumura, Hideki Yamagata
1993 Volume 62 Issue 5 Pages
1474-1477
Published: May 15, 1993
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The nuclear spin-lattice relaxation rate 1⁄
T1 of
63Cu was measured in the range from 1.5 to 300 K for
x=0.0625 and
x=0.08 in (La
1−xBa
x)
2CuO
4. In the high-temperature tetragonal (HTT) and the low-temperature orthorhombic (LTO) phases in the normal state, 1⁄
T1T for both samples follows the Curie-Weiss law,
C⁄(
T+θ), suggesting that the two-dimensional (2D) antiferromagnetic (AF) fluctuation among Cu spins is dominant, similarly to the (La
1−xSr
x)
2CuO
4 system. In the HTT and LTO phases, no significant differences except for a slight difference in θ were observed between the two samples. In the low-temperature tetragonal (LTT) phase for
x=0.0625, 1⁄
T1 diverges at about 35 K, confirming the existence of magnetic ordering. The magnetic ordering at the finite temprature suggedsts that the dominant 2D-AF correlation of Cu spins in the HTT or LTO phase becomes the 3D-AF correlation derived from the some interactions along the
c axis in the LTT phase.
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Hiroshi Kataoka, Sadamu Takeda, Nobuo Nakamura
1993 Volume 62 Issue 5 Pages
1478-1481
Published: May 15, 1993
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The first-order and second-order quadrupolar shifts of the
45Sc nuclear magnetic resonance (NMR) spectrum were investigated in the range of 4 to 300 K in relation to the structural phase transitions of Sc(CH
3COO)
3 and Sc(CD
3COO)
3. It was found that the transition temperature (
Tc) of the deuterated compound was lower (158 K) than that of the protonated compound (167 K). Below the transition temperature, two sets of first-order quadrupolar shifts in the
45Sc NMR spectrum were clearly distinguished, which correspond to the two different sites of scandium ions in the crystal. The magnitude of the splitting, δ(
Δν
Q), between the two different shifts decreased upon heating to
Tc, exhibiting the critical phenomena described by the formula, δ(
Δν
Q)∝[(
Tc−
T)⁄
Tc]
β, where β is close to 1/2 for both isotopic derivatives.
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Muneyuki Date, Koichi Kindo
1993 Volume 62 Issue 5 Pages
1482-1485
Published: May 15, 1993
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Electron spin resonance of URu
2Si
2 single crystals is studied under a high magnetic field in the 50GHz region and a broad and weak resonance line is found in the region where heavy Fermions and weak antiferromagnetism coexist. The resonance line is identified to the antiferromagnetic resonance mode. A striking fact is that the effective
g-value is 0.15 which is very different from the uranium or conduction electron
g-values. This result is explained by introducing a coupled moment of residual 5
f- and Kondo-screening electrons on the uranium atom. About 6.5% of 5
f-electrons screened with 18% of conduction electrons form weak antiferromagnetic moments in the heavy Fermion sea.
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Masaaki Takashige, Sin-Ichi Hamazaki, Masayuki Tsukioka, Fuminao Shimi ...
1993 Volume 62 Issue 5 Pages
1486-1489
Published: May 15, 1993
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Ceramic samples of the mixed system Ba
2NaNb
5(1−x)Ta
5xO
15 were investigated through dielectric measurements. Ferroelectric activity was confirmed through observation of the 50 Hz
D-
E hysteresis loop for samples with
x≥0.4. As a result, the end member, barium sodium tantalate (Ba
2NaTa
5O
15), was assigned as a new ferroelectric below the 40 K range.
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Ryouichi Akimoto, Michihiro Kobayashi, Takashi Suzuki
1993 Volume 62 Issue 5 Pages
1490-1493
Published: May 15, 1993
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The pressure dependence of the photoluminescence spectra in EuSe crystals has been studied up to 2.0 GPa at 77 K and 1.8 K using a diamond anvil cell. At 77 K, the pressure derivative of the peak position of the photoluminescence band is found to be −96 meV/GPa, which coincides with the pressure derivative of the absorption edge. The result supports the interpretation that the emitting state of the photoluminescence is the 5
d(
t2g) state. At 1.8 K, we have observed sharp decrease of the photoluminescence intensity and redshift of the peak energy of about 50 meV with the increase of the pressure beyond 0.4∼0.5GPa. Observed anomalies are interpreted in terms of the pressure-induced phase transition from the antiferromagnetic to the ferromagnetic phase, where the magnetic polaron effect plays a significant role.
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Gen Yoneda, Yoshiyasu Ishigami, Satoshi Arima
1993 Volume 62 Issue 5 Pages
1495-1499
Published: May 15, 1993
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This paper presents four asymptotic conditions of smooth worldlines in Minkowski space that are often used in special relativistic particle dynamics. (A) Permanency with respect to an observer’s time. (B) Permanency with respect to the proper time. (C) Finiteness of the gamma factor. (D) Intersection with the light cone of any apex. The conditions (B) and (D) are free from observers and it is verified that (A) and (C) are invariant conditions for all inertial observers. To examine the inclusion relations between (A), (B), (C) and (D), some inclusion relations are proved and some are denied by counter examples. Then the concluding Venn diagram is obtained. Such researches must interest theoretical physicists who unintentionally use one or plural number of these conditions.
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Hitoshi Sumi, Shin’ichi Higai
1993 Volume 62 Issue 5 Pages
1500-1508
Published: May 15, 1993
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States of an electron bound by an attractive potential on a discrete lattice are usually obtained as eigenvectors in correspondence with eigenenergies solving an eigenvalue equation. The equation is, however, satisfied by all the eigenenergies of a Hamiltonian, irrespective of whether they give bound or unbound states. No systematic method for obtaining only bound states has been known. Perturbational expansion with respect to the attractive potential does not work since bound states disappear if the potential vanishes. It is shown that we can obtain an approximate pair of eigenenergy and eigenfunction of a bound state by applying a decoupling approximation to the potential. The procedure can be repeated by using the approximate eigenfunction thus obtained as a new decoupling function. We can reach the true pair of eigenenergy and eigenfunction systematically by repeating the procedure several times.
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Noboru Hashimoto
1993 Volume 62 Issue 5 Pages
1509-1515
Published: May 15, 1993
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We propose a generalization of the quark jet model based on the geometric picture for hadron-hadron collision. When applied to the process pp→ppX, the generalized model is found to be successful for description of the multiplicity distribution of the remaining mesonic system X. Especially the model reproduces the observed KNO scaling.
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Jiro Ozaki
1993 Volume 62 Issue 5 Pages
1516-1526
Published: May 15, 1993
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We have calculated, from the adiabatic potentials, the total energies and the equilibrium internuclear separations of H
2+ ion in antibonding states δ
u, φ
g, γ
u, and η
g as well as bonding states δ
g, φ
u, γ
g, and η
u in strong magnetic fields. The adiabatic potentials of H
2+ in antibonding states have the minimum when the magnetic field is strong. This means magnetic field stasbilizes dissociative H
2+. With regard to the bonding states, our results reproduce those by M. Vincke and D. Baye [J. Phys. B: At. Mol. Phys.
18 (1985) 167] which are considered to be the most reliable.
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A. K. Datta, S. Acharyya
1993 Volume 62 Issue 5 Pages
1527-1538
Published: May 15, 1993
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The column calibration factors
Fs as a quadratic function of the mean temperatures \bar
T are worked out from the estimated values of the logarithmic maximum separation factors ln
qmax of inert gas isotopic mixtures and their available TD factors α
Ts’ in three columns of comparatively larger geometrical lengths and of varying sizes. The ln
qmax are determined from the pressure dependence of ln
qe in those columns measured by W. M. Rutherford
et al. and W. J. Roos
et al. The nature of temperature variation of
Fs, which depends entirely on the column geometry, allows us to estimate the temperature dependence of α
Ts’ for a wide temperature range. Our α
Ts’ through the use of
Fs are shown to have almost the same order of magnitudes and the same trends as the theoretical ones, while there are larger discrepancies when α
Ts’ are estimated by other methods. This signifies the usefulness of
Fs in column measurements.
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Shinichi Kumashiro, Takeshi Takahashi, Masanobu Ooi, Tsutomu Takahashi ...
1993 Volume 62 Issue 5 Pages
1539-1551
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Fluctuating azimuthal fields,
Bθ, are detected during a lifetime of a Field-Reversed Configuration plasma. The maximum strength reaches to 70 G which corresponds to about 1.5% of a confining field. Sources of the fields are discussed with relation to such plasma motions as radial shifting and tilting motions, and elliptical deformation of the plasma column triggered by a rotational instability. Analytic formulas of the
Bθ are derived from disturbance of the confining field due to these motions. Estimated values from the formulas agree well with field profiles obtained from a magnetic probe array.
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Naoyuki Amemiya, Ayumu Morita, Makoto Katsurai
1993 Volume 62 Issue 5 Pages
1552-1561
Published: May 15, 1993
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The axial compression of flux-core spheromaks is successfully made in the TS-3 facility. Magnetic measurements show that oblate and singlet magnetic configurations are obtained by the axial compression. The closed poloidal magnetic flux surrounding the magnetic axis increases up to 6 mWb, that is three or four times larger than the closed poloidal magnetic flux obtained without the axial compression. During the early and middle phases of the compression, no global instabilities are observed, but, in the late phase, sudden collapses of the flux-core spheromak are observed. This may limit the maximum compression ratio. Fitting to an equilibrium model suggests that, by the axial compression, the ratio μ of the current density to the magnetic field, increases toward the value of the conventional spheromak without core flux.
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Jiro Todoroki
1993 Volume 62 Issue 5 Pages
1562-1582
Published: May 15, 1993
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The theory on the longitudinal adiabatic invariant valid for the helical magnetic field is developed on the basis of the variable transformation from the guiding center variables to the new adiabatic variables. The theory uses the Hamiltonian formalism with non canonical variables. Under the assumption that the rotational transform per period is small, the adiabatic invariant is defined by integral along the toroidal direction, not along the field line. The first order correction to the adiabatic invariant with respect to the expansion parameter is obtained. The transition between the passing and the ripple trapped states is investigated. The jump of adiabatic variables takes place in the transition process, which causes the diffusion of the adiabatic invariant. The transformation of distribution function associated with the variable transformation is also discussed.
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Toshiya Iwai, Hisao Hayakawa
1993 Volume 62 Issue 5 Pages
1583-1596
Published: May 15, 1993
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Domain growth in a system with random impurities for both conserved and nonconserved order parameter is investigated by means of the cell-dynamical system (CDS) method. We find the following. (i) The characteristic length in domain growth obeys
l(
t)∼(log
t)
α where α is smaller than the value predicted by Huse and Henley [Phys. Rev. Lett.
55 (1985) 2708]. (ii) The exponent α seems to depend on the impurity concentration and temperature. (iii) Dynamical scaling of the structure factor is satisfied and the form of the scaling function depends on the impurity concentration.
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Hisashi Haga, Akira Onodera, Masaharu Tokunaga, Yôichi Shiozaki
1993 Volume 62 Issue 5 Pages
1597-1602
Published: May 15, 1993
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Measurements of specific heat were carried out on structurally incommensurate ferroelectrics K
2ZnCl
4 and (NH
4)
2BeF
4 over a wide temperature region with an AC calorimetric technique. Critical indices α associated with the normal-incommensurate phase transition are obtained as 0.12±0.02 for K
2ZnCl
4 and 0.18±0.02 for (NH
4)
2BeF
4. These values do not agree with that in the 3
d XY-model proposed by Bruce and Cowley, and are rather comparable with α=0.125 for the 3
d Ising-model. A crossover from a logarithmic behaviour to a power-law behaviour was found at reduced temperatures
tcr=1×10
−3 for K
2ZnCl
4 and 5×10
−3 for (NH
4)
2BeF
4, respectively.
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Kazumasa Narumi, Yoshikazu Fujii, Keiji Kishine, Shinsuke Fujiwara, Ke ...
1993 Volume 62 Issue 5 Pages
1603-1611
Published: May 15, 1993
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The energy spectra of scattered ions of 12–32 keV H
+, He
+ and N
+ have been measured at glancing angle incidence on the clean (001) and (111) surfaces of Si. A similar formula of the position-dependent stopping power which has been derived for high energy light ions was used to analyze the present results of low energy ions.
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Osamu Narikiyo, Daijiro Yoshioka
1993 Volume 62 Issue 5 Pages
1612-1623
Published: May 15, 1993
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The collective charge-excitation spectrum of a double quantum well system in a strong magnetic field is obtained within the random phase approximation. Correction to the spectrum coming from the finiteness of the magnetic field is calculated up to the first order in inverse of the magnetic field. Dependencies on the magnetic field of (i) the velocity of long wave length excitation and (ii) the phase boundary of the quantum Hall state signaled by the softening of the roton minimum of the spectrum are discussed.
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Akio Kimura, Shigemasa Suga, Tomohiro Matsushita, Hiroshi Daimon, Take ...
1993 Volume 62 Issue 5 Pages
1624-1633
Published: May 15, 1993
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Electronic structures of ferri-, ferro- and antiferromagnetic Cu
2Sb type intermetallic compounds have been studied by ultraviolet and X-ray photoemission spectroscopy (UPS, XPS) as well as by X-ray absorption spectroscopy (XAS). The different spectral features in the core level XPS and the 2p XAS spectra of these materials are discussed by considering the non-equivalent sites of the transition metal atom, M(I) and M(II). The valence band photoemission spectra are also discussed in comparison with the results of recent band calculations.
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Norikazu Tomita, Hideo Fukutome
1993 Volume 62 Issue 5 Pages
1634-1652
Published: May 15, 1993
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We show in the Hartree-Fock approximation that electronic defects which are SDW–CDW domain walls exist in the one dimensional extended Hubbard model of half filling. In the vicinity of the SDW–CDW phase boundary, SDW and CDW polarons and charged solitons split into confined pairs of these defects. They become freely mobile along a chain on the phase boundary. They have ±1⁄4 spins and ±1⁄2 charges in an equidistant lattice and are called halfons. Halfon pairs can convert smoothly the SDW and CDW and can be major quantum fluctuations in the SDW–CDW phase transition. In a bond alternated lattice their spins and charges, respectively, deviate from 1/4 and 1/2. On the SDW–CDW phase boundary, there exist new density waves called the mixed density waves (MDW). Halfons are classified by their trajectories connecting the SDW and CDW via the MDW. We derive the counting rules to explain their fractional spins and charges.
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Atsushi Ikawa, Shoji Yamamoto, Hideo Fukutome
1993 Volume 62 Issue 5 Pages
1653-1668
Published: May 15, 1993
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A tractable direct optimization algorithm is developed to optimize orbitals in the Slater determinants (S-dets) in a resonating Hartree-Fock (Res HF) wave function. We reduce the variation space using the orbitals to put the first order energy variation in the steepest descent direction. The orbitals in the next iteration are determined so as to minimize the energy functional including up to the second order variation. This algorithm is applied to the one dimensional Hubbard model of half-filling. The optimized S-dets much deviate from the trial S-dets prepared from the HF calculations. The Res HF ground state generated with a few S-dets explains from 99.9 to 95.0% of the ground state correlation energy in all the correlation regimes. We have spin correlation functions with the correct short and long range behaviors and the lowest triplet and singlet spin excitations with correct dispersions, suggesting that the optimization of orbitals incorporates long range spin fluctuations and their mode-mode couplings.
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Tatsuya Okada, Satoru Ohno
1993 Volume 62 Issue 5 Pages
1669-1675
Published: May 15, 1993
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The conductivity of liquid In
1−xSe
x alloys decreases rapidly with increasing Se concentration, and shows a deep minimum and a small peak at the composition
x=0.58 and 0.60, respectively. The dependences of the thermopower and the magnetic susceptibility on concentration exhibit a deep minimum and a relatively broad minimum with large negative values at the composition
x=0.58 and 0.60, respectively. The conductivity and thermopower near the stoichiometry In
2Se
3 were analyzed by using the equations derived from the Kubo-Greenwood formula. According to this analysis, the conductivity gap was about 0.4 eV for liquid alloys near the stoichiometry.
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Mikio Koyano, Shigeo Ôhara, Yoshiaki Hara, Masasi Inoue, Giyuu K ...
1993 Volume 62 Issue 5 Pages
1676-1681
Published: May 15, 1993
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Magnetoresistance and Hall effect have been measured at 4.2 K using a hybrid magnet up to 26 T for several crystals of quasi-two-dimensional η-Mo
4O
11 that has a charge-density-wave (CDW) induced nested multiple carrier band structure. The magnetoresistance is exceptionally large and the Hall resistivity shows a unique magnetic field dependence. We have confirmed the existence of characteristic hysteresis phenomena in both quantities between up- and down-sweeps of an applied magnetic field, as well as Shubnikov-de Haas (SdH) oscillations. The hysteresis effects can be related with a magnetic field dependent
irreversible process for the CDW formation and destruction. These transport properties are found to be sample-dependent.
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M. A. Khan
1993 Volume 62 Issue 5 Pages
1682-1691
Published: May 15, 1993
Released on J-STAGE: May 29, 2007
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A supercell with thin layers of empty spheres (
Es) between two successive metallic slabs is constructed. This supercell is then studied for its electronic structure by Linear Muffin Tin Orbitals (LMTO) method in its Atomic Sphere Approximation (ASA). A sufficient number of
Es layers is used to break the inter-slab bonding. Computational results of the magnetic moments of V(001) films for different lattice constants are presented. The single overlayers of Pd and V on Ag(001) surface show paramagnetic behaviour for Pd overlayer while a ferromagnetic stability for V overlayer with a small magnetic moment. Finally, the interband transitions in Pd/Ag(001) and V/Ag(001) are presented.
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Takeshi Inaoka
1993 Volume 62 Issue 5 Pages
1692-1701
Published: May 15, 1993
Released on J-STAGE: June 01, 2007
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In small coated particles, the internal and external surface excitations of the shell material and the surface excitation of the core material interact with one another. We examine how the inner and outer surface excitations of the shell are coupled with each other in the presence of the dielectric core, and how this coupling varies its characteristics with change of the shell thickness, the multipole order and the core dielectric constant. In addition, we make a similar analysis of the effect of the dielectric coating on the surface excitation of the core. Although we employ a simple approach of the local response theory, our results do not depend upon the explicit frequency dependence of the local dielectric function characterising the shell or core material.
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Masaaki Matsuda, R. J. Birgeneau, Yasuo Endoh, Yoshikazu Hidaka, M. A. ...
1993 Volume 62 Issue 5 Pages
1702-1709
Published: May 15, 1993
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Neutron scattering experiments have been performed to study the dynamic spin properties of La
1.98Sr
0.02CuO
4, a crystal with just enough Sr to destroy three-dimensional long range magnetic order and induce spin-glass behavior at low temperatures. The
q-integrated susceptibility ∫d
2q2D Im χ
2D(
q2D, ω) follows the scaling function of ω⁄
T suggested by Keimer
et al. Below 3 meV, however, clear deviation from the scaling function is observed at low temperatures. This probably originates from a gap in the spin-wave-like excitations due to the out-of-plane anisotropy.
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Yoshihiro Yamada, Akihiko Sakata, Tetsuro Murakami
1993 Volume 62 Issue 5 Pages
1710-1715
Published: May 15, 1993
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The C-14 Laves phase NbFe
2 is a very weak antiferromagnet with ferromagnetic spin fluctuations. The magnetic properties of the Al-substituted Nb(Fe
1−xAl
x)
2 system were investigated for
x≤0.5 by NMR and magnetisation measurements. It was found that the antiferromagnetism is enhanced by the Al substitution for
x≥0.05, while for
x<0.05 very weak ferromagnetism appears. The origin of the ferromagnetism is discussed.
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David N. Timms, Eugeniusz Zukowski, Malcolm J. Cooper, David Laundy, S ...
1993 Volume 62 Issue 5 Pages
1716-1722
Published: May 15, 1993
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The existence of a term in the cross section for inelastic photon scattering of circularly polarised photons which is dependent on orbital magnetisation has been proposed and supported by evidence from one Compton scattering experiment carried out at 45 keV. The integrated intensity of the Compton scattering is studied as a function of the angle between the incident beam and the direction of magnetisation. Further measurements of a similar nature on the same samples, Fe, Co, HoFe
2, which have produced negative results, are reported here. These latest results, which were obtained at two different synchrotron rings (the Daresbury Storage Ring and the KEK Accumulation Ring), throw doubt upon the importance of such effects in the Compton limit.
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Junji Iida, Midori Tanaka, Yasuaki Nakagawa, Satoru Funahashi, Noboru ...
1993 Volume 62 Issue 5 Pages
1723-1735
Published: May 15, 1993
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Magnetization, neutron diffraction and Mössbauer measurements have been performed on a two dimensional (2D) double-layered triangular antiferromagnet LuFe
3+Fe
2+O
4 single crystal. Two magnetic rods (0, 1,
l) and (1/3, 1/3,
l) with broad widths across them reveal that 2D magnetic ordering is not of long range and no 3D one occurs down to 4.2 K in contrast to an ordinary magnetic system. Thermoremanent magnetization measurements suggest that the system consists of various size ferrimagnetic clusters. The characteristic profile of
l-scan in (0, 1,
l) can be realized by taking account of correlation among clusters for intra double-layers and inter double-layers. The temperature variations of intensity in magnetic scattering can be explained qualitatively by assuming unequal exchange interactions among three sublattice.
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Katsuhiko Takegahara
1993 Volume 62 Issue 5 Pages
1736-1744
Published: May 15, 1993
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Using a quantum Monte Carlo simulation technique, we study magnetic properties of the 6-fold degenerate Anderson model, which corresponds to the angular momentum
j=5⁄2. The model is characterized by the
f-
f Coulomb interaction
U, the hybridization width
Γ, and the
f-electron energy level
Ef. As
U increases, the Kondo temperature
TK decreases for the electron-hole symmetric case (
Ef∼−5
U⁄2), although
TK increases for the shallow
Ef case (
Ef∼0). We also study an effect of cubic crystal field splitting
Δc on the susceptibility and the Kondo temperature, and find a suppression of susceptibility and an increase of
TK when the occupied
f-electron number is nearly equal to one. In processes of Monte Carlo simulations, the negative sign problem does not appear.
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Noriaki Matsunaga, Youiti Ootuka
1993 Volume 62 Issue 5 Pages
1745-1749
Published: May 15, 1993
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The magnetization of phosphorus doped silicon is measured in the magnetic fields up to 5 kG over the temperature range from 10 mK to 4.2 K at phosphorus concentrations from 5.3×10
17 to 4.5×10
18 cm
−3. The dependence on temperature and on magnetic field is explained by the localized spin model even in the lightly metallic region.
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Akira Oyamada, Atsushi Isobe, Hideaki Kitazawa, Akira Ochiai, Takashi ...
1993 Volume 62 Issue 5 Pages
1750-1757
Published: May 15, 1993
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Magnetic susceptibilities, electrical resistivities and specific heats of Ce
2Sb, Ce
2Bi and CeLaBi were measured to clarify these physical properties. The most characteristic points of these compounds are the following. Ce site are two dimensional and the distance between Ce atoms are very small. The similarity between these compounds and CeRh
3B
2, in which Ce sites are one dimensional and the distance between Ce atoms are very small, are discussed.
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Toshikazu Hirose, Masaru Kawaminami, Kozo Obara, Masanori Arakawa, Hid ...
1993 Volume 62 Issue 5 Pages
1758-1766
Published: May 15, 1993
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The dielectric constant ε′(ω,
T), ε″(ω,
T) and the electric conductivity σ(ω,
T) of Bi
2−xGd
xWO
6 single crystals have been measured in the temperature range from 350 K to 4.2 K and at frequencies from 20 Hz to 1 MHz. EPR measurements with an X-band spectrometer have been made on Gd
3+-doped Bi
2WO
6 crystals. Two kinds of centres observed are ascribed to Gd(1) and Gd(2) ions substituted for Bi(1) and Bi(2) ions, respectively. Fine structure parameters obtained are |
b20|=1367, 1138, and |
b22|=1060, 384 in units of 10
−4 cm
−1. Temperature dependence of resonant fields for the Gd(1) centre shows a marked difference from that for the Gd(2) centre. This is due to the difference between the coupling of the two Gd ions to phonon modes.
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Akihiko Ishibashi, Masayuki Watanabe, Tetsusuke Hayashi
1993 Volume 62 Issue 5 Pages
1767-1777
Published: May 15, 1993
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Emission spectra and decay characteristics of exciton luminescence in Pb
1−xCd
xI
2 solid solutions have been investigated for a wide range of the composition
x. Continuous shift of the absorption edge toward higher energy with increasing
x is ascribed to reduction in the band-width of the exciton associated with 6s-6p transition of Pb ions. The emission band appearing near the absorption edge of the solid solutions with
x below 0.5 is attributed to the luminescence of excitons localized at various potential wells induced by the composition fluctuation. An essential change in the excited state character from the excitonic state to the excitation of Pb ion clusters is found to take place at the composition
x around 0.5.
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Kaoru Iwano, Keiichir\={o} Nasu
1993 Volume 62 Issue 5 Pages
1778-1781
Published: May 15, 1993
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Nonlinear optical properties in halogen-bridged mixed-valent platinum complexes are studied theoretically for the first time. Two types of nonlinearities are treated here. One is the electric-field modulation of the absorption spectrum, and the other is the third-harmonic generation. The spectral shapes of these nonlinearities are determined by a method in which both effects of the electron-hole correlation and the lattice fluctuations are taken into account. As for the electric-field modulation, the difference spectrum observed in the visible region for [Pt(en)
2][Pt(en)
2Cl
2](ClO
4)
4 is well reproduced with features such as the rigid shift of the main charge-transfer band and the newly appearing peak due to the parity-even exciton. On the other hand, in the spectrum of the frequency-dependent intensity of the third-harmonic generation, several enhancements are found: the three-photon resonance structure due to the parity-odd exciton and the free electron-hole continuum, and the two-photon resonance peak due to the parity-even exciton. In particular, the last one seems to correspond to that observed in the experiment.
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