-
Kazuo Hida
1993 年 62 巻 10 号 p.
3357-3360
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
The location of the XY phase in the ground-state phase diagram of the spin-1/2 anisotropic ferromagnetic-antiferromagnetic alternating Heisenberg chain is determined. This model reduces to the spin-1 XXZ chain if the ferromagnetic bond is infinitely strong. The phase boundary between the XY phase and the Haldane phase is determined from the analysis of the numerically obtained energy spectrum of finite-sized systems with the open boundary condition. Our results are consistent with the series-expansion results by Yamanaka
et al. within their error bars. The boundary between the ferromagnetic phase and the XY phase is also determined by comparing the energy eigenvalues of these two phases.
抄録全体を表示
-
Hironari Miyazawa, Yukio Obata, Hiroshi Suura
1993 年 62 巻 10 号 p.
3361-3363
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
The mechanism for producing abundant negative pions by stimulated emission is discussed. The power required to operate such a PASER is proportional to its linear dimension and is such that can be realized in practice. Possible applications to muon-catalyzed fusion are discussed.
抄録全体を表示
-
Tadao Kasuya, Masafumi Sera, Takashi Suzuki
1993 年 62 巻 10 号 p.
3364-3367
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
Various anomalous properties in CeSb are studied critically. It is shown that they are explained consistently by the formation of a partial magnetic polaron, which disappears with La substitution and is enhanced under pressure, and by a modified Kondo state through an anomalous
p-
d mixing. However, no Kondo effect is observable at low temperature.
抄録全体を表示
-
Hiroshi Kamimura, Yuji Suwa
1993 年 62 巻 10 号 p.
3368-3371
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
A new theoretical explanation is given for the superconducting state in copper oxides. The key feature of the state is the following. A coherent motion of itinerant holes from low-spin to high-spin states in the presence of a relatively long-range antiferromagnetic ordering of the Cu localized spins creates a superconducting state. Based on this state, it is suggested that the attractive interaction between two holes in different energy bands with the same dispersion mediated by Jahn-Teller-type optic phonons is primarily responsible for superconductivity.
抄録全体を表示
-
Yuri V. Sushko, Hiroshi Ito, Takehiko Ishiguro, Sachio Horiuchi, Gunji ...
1993 年 62 巻 10 号 p.
3372-3375
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
Application of a high magnetic field to the pressure-stabilized superconducting state appearing below
Tc1 in κ-(BEDT–TTF)
2Cu[N(CN)
2]Cl enhances/induces a resistive ground state below
Tc2 (<
Tc1). The resistivity in the field-induced phase is insensitive to temperature variation. The field-induced transition is also characterized by a marked resistivity versus field hysteresis and by a pronounced long-time dependence.
抄録全体を表示
-
Tadao Kasuya, Yoshinori Haga, Takashi Suzuki, Toyotaka Osakabe, Masahu ...
1993 年 62 巻 10 号 p.
3376-3379
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
The magnetic orders in CeP under applied magnetic field of up to 70 T are studied based on the layered-type
Γ8 magnetic polaron lattice model studied in the previous paper. Entropy changes, total induced moments and results of neutron scattering in various phases are explained consistently. Fermi surface nesting is important to keep the period constant.
抄録全体を表示
-
Hideyuki Sato, Yoshihiko Kobayashi, Yuji Aoki, Kazuhiko Shintaku, Nobu ...
1993 年 62 巻 10 号 p.
3380-3383
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
The magnetoresistance (MR) at 4.2 K and the temperature dependence of resistivity have been investigated for Au/Fe epitaxial superlattices as a function of Au layer thickness. We found −log (
T) temperature dependence of resistivity below about 10 K. The magnitude oscillates as a function of Au layer thickness in phase with the MR oscillation.
抄録全体を表示
-
Tetsuya Kato, Toshiya Ishii, Yoshitami Ajiro, Takayuki Asano, Shinji K ...
1993 年 62 巻 10 号 p.
3384-3387
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Neutron diffraction measurements of single-crystal RbMnBr
3 have been performed under magnetic fields applied parallel to the
a*-axis of the prototype lattice, where the structural phase transitions are not taken into account. The critical line of a field-induced phase transition, at which the modulation wave number of the spin structure changes, has been obtained in the magnetic phase diagram for 4.2<
T<11 K and 0<
H<5.0 T, in addition to the in-
c-plane spin-flop phase transition.
抄録全体を表示
-
Takashi Kambe, Hidekazu Tanaka, Kazukiyo Nagata
1993 年 62 巻 10 号 p.
3388-3391
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
We investigate the effects of a diagonal interchain interaction
J2 on the ESR modes in the
ABX3-type antiferromagnets with easy-axis anisotropy.The static properties are described by replacing the conventional interchain interaction
J1 by
J1−2
J2. However, because of the phase difference between the sublattice magnetizations,
J2 coupling produces marked effects on some ESR modes in cooperation with
J1 coupling. Large separation between the ω
1-mode and EPR line for
H⊥
c and ω
2- and ω
3-modes for
H⁄⁄
c (
H>
HSF) can be derived by maintaining consistency with the canting angle of spins from the
c-axis and the spin wave dispersion at zero field. ESR measurements in CsMnI
3 are reported. The frequency-field diagram obtained is described well by the model involving
J2 coupling.
抄録全体を表示
-
Kiyoshi Deguchi, Eiji Nakamura
1993 年 62 巻 10 号 p.
3392-3394
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The Rhodes-Wohlfarth ratio μ
c⁄μ
p, where μ
c is the dipole moment determined from the Curie-Weiss constant and μ
p the saturated dipole moment, was examined for LiTlC
4H
4O
6·H
2O (LTT), a displacive ferroelectric having a low Curie temperature of 10 K. The value of μ
c⁄μ
p of LTT is obtained to be about 18, which is much larger than those of other ferroelectrics examined previously. This result supports Tokunaga’s prediction that μ
c⁄μ
p of displacive ferroelectrics with low Curie temperature exhibit large deviation from unity.
抄録全体を表示
-
K\={o}shi Koide, Yutaka Toyozawa
1993 年 62 巻 10 号 p.
3395-3401
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
A Gedankenexperiment is presented on the effect of imperfect detection of the electron path on the double slit interference pattern. Incorporating into our quantum system the detectors for the electron path and the observer who recognizes the response of the detectors, one can decompose the ensemble of electrons with their spots on the film into three subensembles according as the upper, lower or neither detector responds. Only the third ensemble shows the interference pattern. Negative result measurement is included as a special case. This Gedankenexperiment allows one to put the argument of Bohr’s complementarity of the wave/particle duality on a quantitative basis. The realization of the experiment is well within the high technology of the present day.
抄録全体を表示
-
Tohru Koma
1993 年 62 巻 10 号 p.
3402-3412
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
We question the validity of the finite-size-correction method based on conformal field theories. It is shown that the method leads to incorrect critical exponents on some of the correlation functions for a one-dimensional free fermion model. The model exhibits the same critical behaviour as in the well-known square-lattice Ising model that is believed to be conformally invariant.
抄録全体を表示
-
Yoichiro Furutani, Koichi Ohashi, Masahiro Shimizu, Atsushi Fukuyama
1993 年 62 巻 10 号 p.
3413-3424
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The Thomas-Fermi-Dirac-Weizsäcker statistical model of atoms is applied to a compressed diatomic molecule in a dense plasma. As a two-dimensional problem, we analyze numerically a spatial profile of the screening function and the electron density inside a closed boundary surface. We also calculate the Helmholtz’s excess free energy as a function of the internuclear distance, to examine a possibility of the binding state.
抄録全体を表示
-
Hidetoshi Suemitsu, Hideki Kitaura, Katsushi Seki
1993 年 62 巻 10 号 p.
3425-3431
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The relative production rates of Cs
2+ ions produced through two-photon ionization of cesium dimers Cs
2 were measured in the wavelength range 620–670 nm. The calculated production rates of Cs
2+ ions produced via the intermediate state C
1Πu from X
1Σg+ agreed fairly well with the experimental results. The production rates via the intermediate state
1Σu+, which is close to C
1Πu, were calculated. The calculated results, however, showed the completely different function of wavelength from that of the experimental results. Thus we concluded that Cs
2+ ions are mainly produced by the processes via the intermediate state C
1Πu. It was made clear that most of the cesium dimers Cs
2 excited in the super excited states Cs
2** by absorption of two photons are autoionized to produce Cs
2+ ions.
抄録全体を表示
-
T. P. Pandya, L. M. Bali, P. Jha, A. Srivastava, R. K. Shukla, V. Saxe ...
1993 年 62 巻 10 号 p.
3432-3440
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Spontaneous and coherent emission of radiation in a FEL with planar wiggler and axial magnetic fields is investigated. The eccentricities of the resulting electron trajectory and spontaneous emission are seen to be different. On interaction with e.m. radiation electron orbits give rise to elliptically polarised coherent emission at principal and harmonic frequencies. Beam amplifications at higher harmonics peak at lower axial field strengths. The peak gains are significantly larger than the gain obtained at the next lower frequency in the absence of axial magnetic fields.
抄録全体を表示
-
Yong Kweon Suh
1993 年 62 巻 10 号 p.
3441-3445
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Motion of a point vortex in a 90°-corner which is subject to a potential flow is studied. There exists a fixed point at which the vortex is stationary. It turns out that the vortex motion is periodic regardless of the initial position except the fixed point. The fixed point is apart from the corner in a distance proportional to the square root of the ratio of the vortex strength (circulation) and the strength of the potential flow. The period of the circulatory motion of the vortex in a small vicinity of the fixed point is in inverse proportion to the potential-flow strength and is independent of the vortex strength. The motion of the fluid driven by both the potential flow and the vortex is also studied; depending on the location of the stagnation points, generally four kinds of flow patterns are classified.
抄録全体を表示
-
Isao Katanuma, Yasuhito Kiwamoto, Nobuyoshi Ohyabu, Kameo Ishii, Kiyos ...
1993 年 62 巻 10 号 p.
3446-3459
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The electron distribution function is derived analytically with the linearized Fokker-Planck equation in order to analyze the electron confining potential in the geometry of mirror ratio
R<<1. The magnitude of the potential is determined by the electron axial loss time (transit time) τ
⁄⁄ when τ
⁄⁄ is longer than the coulomb collision time τ, on the other hand the magnitude of the potential depends mainly on τ when τ
⁄⁄\lesssimτ. Especially, it is found that the electron confining potential does not depend on the emission rate γ of electrons hitting the wall as long as τ
⁄⁄<<τ.
The bounce-averaged nonlinear Fokker-Planck simulation is carried out in order to investigate the electron confining potential in the case of
R=1. The electron temperature ratio
Te⊥⁄
Te⁄⁄ depends strongly on the ratio τ⁄τ
⁄⁄. The magnitude of the potential obtained in the simulation has a tendency to decreasing with the ratio τ⁄τ
⁄⁄.
抄録全体を表示
-
Mitsuhiro Nambu
1993 年 62 巻 10 号 p.
3460-3475
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The plasma-maser process including electrostatic waves propagating obliquely to an external magnetic field is studied. It is shown that the results based on the linear response theory agree with the previous standard results obtained by M. Porkolab and R. P. H. Chang (Phys. Fluids
15 (1972) 283). It is found that the polarization term for a magnetized plasma gives a finite contribution to the plasma maser in contrast to the case of an unmagnetized plasma, and that the results for the magnetized plasma reduce to those for the unmagnetized plasma in the limit of zero magnetic field. There does not exist discontinuous jump between the expressions for the unmagnetized and magnetized plasmas.
抄録全体を表示
-
Kazuyuki Ohe, Shigeki Hayashi, Takashi Kimura
1993 年 62 巻 10 号 p.
3476-3485
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
Two ionization wave modes simultaneously excited in a low discharge current He positive column are detected by an auto-regression method. One dominant mode which slightly damps can be predicted by the dispersion relation calculated under the assumption that a group of electrons are resonant with a peculiar wave characteristic voltage. The dispersion relation obtained experimentally for the other evanescent mode agrees well with the theoretical dispersion calculated from the hydrodynamic equations using the two-electron temperature approximation.
抄録全体を表示
-
Masayoshi Taguchi
1993 年 62 巻 10 号 p.
3486-3491
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
A poloidally varying electrostatic potential due to a plasma heating anisotropic in velocity space is investigated in the collisionless regime for an axisymmetric plasma. Based on a linearized drift kinetic equation in a presence of external energy-source term, an analytic expression for this electrostatic potential is derived by means of an eigenfunction technique and a variational method. By using this analytic expression, the enhancement of the neoclassical transport coefficients by the anisotropic heating is discussed.
抄録全体を表示
-
G. Gnudi, Tsuguhiro Watanabe
1993 年 62 巻 10 号 p.
3492-3505
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
A new method for integrating differential equations is presented. The method is explicitly described until the order 14, and it has been proven to be A-stable and symplectic with respect to linear Hamiltonian systems.
抄録全体を表示
-
Ryo Maruta, Atsuya Makita, Ken-ichi Ohshima
1993 年 62 巻 10 号 p.
3506-3512
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
X-ray measurements have been performed on the structure of layered compound Cu
0.15Ti
1.08S
2 at room temperature. Weak diffuse scatterings at (1/2, 0, 3/2), (1/2, 1/2, 3/2) and (1, 1/2, 3/2) in reciprocal space are observed. This reveals that both the intercalated copper atoms and self-intercalated titanium atoms are three-dimensionally correlated with each other and the stacking sequence αβαβ… is deduced. By analyzing diffuse intensity, the short-range order (SRO) parameters were determined. A 2×2 in-plane ordered structure is expected for the low temperature phase. The estimated in-plane and interlayer correlation lengths are about 12 A.
抄録全体を表示
-
Takashi Sakuma, Fumihito Suzuki, Shoji Saitoh, Kazumasa Sugiyama, Eiic ...
1993 年 62 巻 10 号 p.
3513-3518
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
The diffuse background intensity of α-Cu
2Se was observed by the anomalous X-ray scattering (AXS) measurement at the Cu
K-absorption edge using synchrotron radiation. The theoretical treatment including the effects of the correlation between the thermal displacements of atoms was applied to the analysis of the observed diffuse background of α-Cu
2Se. The structural model for α-Cu
2Se formerly reported by the present authors has been confirmed by the analysis of the diffuse background.
抄録全体を表示
-
Yoshiyuki Matsumoto, Kiyoshi Ogura
1993 年 62 巻 10 号 p.
3519-3526
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The Slater and the Takagi models of the ferroelectric phase transition in KH
2PO
4 (KDP) have been extended to the model that the number of each proton configuration depends on time. We adopt the two proton configurations proposed by Silsbee
et al. besides the Slater’s and the Takagi’s configurations. The dynamical susceptibility, χ(ω), is obtained in the form of the sum of two Debye-type functions, where we have gained two relaxation times with different temperature dependence. One of them, τ
− tends to infinity when temperature approaches the transition point from the paraelectric region. This feature is very similar to the results of Yoshimitsu
et al. Next, we determine the three orientation energies, ε
0, ε
1 and ε
2, using some experimental results and then calculate two relaxation times numerically. The polarization relaxation mode is found in the narrow frequency region within 0∼0.5 cm
−1.
抄録全体を表示
-
Tomoyuki Hikita, Yoshiko Tezuka
1993 年 62 巻 10 号 p.
3527-3531
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
Ultrasonic velocity and attenuation were measured on TSCC single crystals at 10 MHz. The longitudinal sound was propagated along the
a,
b and
c axes. The velocity was measured by pulse-echo-overlap-method. The sound velocities along the
a and
c axis show a sharp drop at
Tc, whereas the attenuation coefficients a sharp peak (width of less than 0.1 K) at the same temperature. These anomalies can be analyzed by Landau-Khalatonikov process. The longitudinal sound propagated along the ferroelectric
b axis also shows anomalies in velocity and attenuation. However the width of the peak of the attenuation is about 1.3 K and is much wider than those of perpendicular ones. The anomalies in this direction were interpreted in terms of the peculiar nature of this ferroelectric where the short range interaction is playing important role for the phase transition.
抄録全体を表示
-
Yoji Ohashi, Masashige Matsumoto
1993 年 62 巻 10 号 p.
3532-3538
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The band motion of muons in superconductors is studied in detail. Both the damping rate and the effective mass of the muon due to the interaction with conduction electrons are examined. Then, the average hopping rate of a muon is obtained by combining these quantities. The results are compared with that obtained by the double-well model and the relation between the two is discussed. In addition, as an extention of our theory, the quantum diffusion in some unconventional superconductors is also examined.
抄録全体を表示
-
Takafumi Kita
1993 年 62 巻 10 号 p.
3539-3556
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Broken time-reversal (
T) symmetry of anisotropic superfluidity implies topological change of the whole Fermi sphere. An infinite string pierces through the Fermi sphere; the phase of the pair state |
k, −
k〉
s is multivalued around it; and at
T=0, the one-particle occupation number
n(s)(
k) vanishes on the string. Through these observations, this paper settles the problem of the intrinsic orbital angular momentum in
3He–A: The momentum density at
T=0 is given by
g=
NsMvs+(1⁄4)∇×(
Nsh
l)−(h⁄2)
C0l(
l·∇×
l) with
C0=0, namely, the third term is absent due to
n(s)(
k)=0 for
k⁄⁄
l. The process reveals that the Green’s function approach based on the plane wave expansion fails to describe the topological change. Also, the conclusion raises several basic problems such as the divergence of
Hc2 for T-breaking superconductivity. Finally, this paper presents a principle connecting the magnetic field with the phase singularity of the wave function. Its implications to the charged-anyon model and the Dirac monopole are also discussed.
抄録全体を表示
-
Shintaro Mori, Miki Wadati
1993 年 62 巻 10 号 p.
3557-3564
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
In the studies of the curvature instability, the phase separation of the intercalated particles in the membrane and the amphiphilic molecules has been assumed. In the present paper, we discuss another mechanism; we consider the case where the intercalated particles move diffusively except for the coupling with the curvature of the membrane. The instability conditions are explicitly shown for flat and spherical cases. Based on the results, we give an intuitive explanation to the reversible echinocytosis of the red blood cell. We also discuss the application to the multi-component microemulsion systems.
抄録全体を表示
-
Shintaro Mori, Miki Wadati
1993 年 62 巻 10 号 p.
3565-3574
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
We discuss the condition for the curvature instability in d-dimensional surface. We give necessary and sufficient conditions for the instability in the cases where the order parameters on the membrane are described by the φ
4-theory and the spherical model. In the spherical model case, applying Large
D expansion (where
D is the dimension of the bulk space in which the membrane is embedded), we obtain the phase diagram of this system.
抄録全体を表示
-
Susumu Ogawa, Shigemasa Suga, A. E. Bocquet, Fumitoshi Iga, Mitsuo Kas ...
1993 年 62 巻 10 号 p.
3575-3589
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
We report on X-ray photoemission (XPS), Bremsstrahlung isochromat (BIS) and 4
f resonant ultraviolet photoemission (4
f RPES or UPS) spectroscopy of Ce(Pd
1−xCu
x)
3 (0≤
x≤0.133). With increasing
x, the 4
f1 BIS peak clearly observable in CePd
3 is strongly depressed, the 4
f2 BIS peak is found to shift to lower energies and the intensity of the 3
d94
f0 component of the Ce 3
d core XPS is found to become weaker. These experimental results are discussed in comparison with the spectra calculated by using the impurity Anderson model. It is found that lowering of the 4
f level energy ε
f along with reduction of the 4
f hybridization strength
V with
x can qualitatively reproduce the experimental result. It is also strongly suggested that the 4
f-4
f Coulomb energies are different for the 4
f BIS and 3
d XPS final states.
抄録全体を表示
-
Kazuo Soda, Tamiko Mori, Hideaki Kitazawa, Masayuki Hagiwara, Koichi K ...
1993 年 62 巻 10 号 p.
3590-3597
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
We have measured the valence-band photoelectron spectra of (La
1−xSr
x)
2CuO
4−δ single crystals. Spectra obtained at low temperatures (30–80 K) are similar to each other as well as the results reported so far: The intensity at the Fermi level is quite low and the valence-band maximum is shifted to higher binding-energy than what the energy-band calculation predicts. At room temperature the intensity of the 3 eV band is reduced rapidly while the specimen is kept in dark, while it shows a quick recovery when the specimen is exposed to the excitation light for photoelectron measurements. This suggests that a photo-assisted process may take part in this phenomenon. Some possible mechanisms for the photo-induced changes are discussed.
抄録全体を表示
-
Yoshiki Hori, Keita Kishigi, Kazushige Machida
1993 年 62 巻 10 号 p.
3598-3608
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The charge or spin density wave (DW) formation in one-dimensional (1D) electron systems under an external incommensurate potential is shown to be characterized by infinitely many order parameters (MOP) and infinitely many mean-field solutions with almost degenerate energies. We investigate various properties of such a DW state, including the band structure and the relative magnitude of the OP’s as functions of the strength and period of the external potential. The complexity of the configuration space of the mean-field solutions is described by ultrametricity. The observed field-induced SDW transition of 2D systems such as (TMTSF)
2X is discussed where the magnetic field plays a role of the incommensurate potential in this context.
抄録全体を表示
-
Y.-R. Jang, B. I. Min
1993 年 62 巻 10 号 p.
3609-3614
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The quasi-particle spectral weight at the Fermi level (
ZF) in the two-dimensional (2D) electron gas is determined as a function of density. A model local field correction factor (
G(
q)) possessing the correct features both in the small and large q limits is introduced and used to calculate the
ZF, by evaluating the electron self-energy within the GW approximation. It is found that the
ZF calculated using the present
G(
q) is smaller than the one calculated using the Hubbard
G(
q) implying that the correlation interaction makes the system more localized. Our result also indicates that high
Tc superconductors, if described by a 2D electron gas system, will exhibit a small but nonzero (∼0.2) quasi-particle spectral weight at the Fermi level.
抄録全体を表示
-
Yamichi Ohmura
1993 年 62 巻 10 号 p.
3615-3620
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
It has been shown that unusual hole concentration changes in
p-type Si and Ge under stress reported in the earlier work are well accounted for in terms of density of states (DOS) change of each hole due to stress. The DOS of heavy-hole band decreases, while that of light-hole band increases near the band edge region for both tensile and compressive stresses, which impedes the carrier transfer and hence results in extremely small, nearly stress-quadratic hole concentration changes. It has also been demonstrated that, when these DOS changes overwhelm the carrier transfer effect, even the decrease of the low-energy heavy hole concentration takes place at low temperatures.
抄録全体を表示
-
Hiroshi Kaneko, Takehiko Ishiguro, Jun Tsukamoto, Akio Takahashi
1993 年 62 巻 10 号 p.
3621-3632
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Highly conductive heavily iodine-doped polyacetylene changes from metallic to nonmetallic by room-temperature aging. For this change, thermoelectric power varies little, suggesting that the transition is not ascribed to change in carrier concentration but to increase of the degrees of disorder. Corresponding to the transition, low temperature magnetoresistance changes from negative to positive on crossing the transition. The magnetoresistance in the metallic region is interpreted in terms of weak localization, while that in the nonmetallic state is explained by field effect to variable range hopping conduction among Anderson localization states. The transition to the nonmetallic state proceeds inhomogeneously.
抄録全体を表示
-
Tsuyoshi Ueta
1993 年 62 巻 10 号 p.
3633-3638
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Behavior of an electron beam injected from a waveguide into an open space in magnetic fields is studied by the method analogous to that Kirchhoff applied to the diffraction of light. It is found that magnetic field quantum-mechanically collimates electron beams. An electron beam injected from an orifice travels longer distance than that classical theory predicts before reflection on the boundary. Substructure of electron beams around the reflection point is interpreted by introducing the effect of magnetic fields to the diffraction theory in the absence of a magnetic field.
抄録全体を表示
-
Ken-ichi Oshio, Hideo Yahata
1993 年 62 巻 10 号 p.
3639-3650
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
A one-dimensional model system of the Gunn-effect device is considered. It consists of an
n+-
n-
n+ GaAs sandwich structure where the high-
n+ contact layers on both ends are linearly graded to the uniformly distributed low-
n bulk region and a half-wave sinusoidal doping notch is incorporated near the cathode. Using the finite differece method, spatio-temporal evolution of the system subject to the dc and the rf-alternating fields is computed with the amplitudes and the frequency being taken as the control parameters. Current oscillations associated with the cyclic traveling high-electric-field domain are shown to materialize over a range of the control parameters. In particular, the current oscillations become chaotic at specially chosen values of these bias parameters.
抄録全体を表示
-
Tsuyoshi Yamaguchi
1993 年 62 巻 10 号 p.
3651-3660
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
Electronic states are calculated by the DV–Xα–LCAO method for two model clusters C
60Si
57H
44 and C
60Si
41H
36 of the C
60/Si(001) surface, where the C
60 molecule resides on four and two Si dimers, respectively. Due to the electron transfer from the Si surface, the C
60 molecule of the former (latter) cluster has ionicity −2.44 (−1.96). The highest occupied molecular orbital (HOMO) of the C
60 molecule of the former cluster is lower than that of the latter cluster. This implies that the C
60 molecule of the former cluster is more stable than that of the latter cluster. For both clusters, occupied (unoccupied) orbitals of the C
60 molecule near the HOMO have high charge density around double bonds between two hexagons (around single bonds on pentagons). The charge density of an orbital has 4 or more stripes which should be compared with the scanning tunneling microscopy images.
抄録全体を表示
-
Koichi Ichimura, Kazushige Nomura
1993 年 62 巻 10 号 p.
3661-3679
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The electron tunneling study was carried out on Bi
2Sr
2CaCu
2O
8 with use of the scanning tunneling microscope. Both the cleaved and lateral surface of single crystal were investigated. The electronic density of states for the superconducting phase was correctly obtained at the lateral surface. It shows the finite gap on the whole Fermi surface clearly, while the gap has a considerable anisotropy. The temperature dependence of the magnetic field penetration depth was also measured and its thermally activated behavior confirmed the finite gap again. These results indicate the large
s-wave component in the pair wave function and the fair contribution of
d-wave as well. The attractive force between electrons is not only due to the on-site interaction, but also the extended one.
抄録全体を表示
-
Manabu Ikebe, Yoshihisa Obi, Hiroyuki Fujishiro, Hiroyasu Fujimori
1993 年 62 巻 10 号 p.
3680-3685
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The dimensional crossover from anisotropic three-dimensional to two-dimensional behavior in the temperature dependence of the parallel critical field has been studied for Nb/Al
2O
3 superconductive multilayers as a function of the structural modulation wavelength λ. The thicknesses of the superconductive Nb sublayer (
d Nb) and the Al
2O
3 tunneling barrier sublayer (
d Al
2O
3) were varied up to 100 Å. In accord with the calculation due to Deutscher and Entin-Wohlman, the crossover occurs in the vicinity of
T*, where the perpendicular coherence length ξ
⊥(
T) satisfies the relation, 1.4ξ
⊥(
T*)=λ, irrespective of the ratio λ⁄
d Nb.
抄録全体を表示
-
Fumihisa Suzuki, Chikara Ishii
1993 年 62 巻 10 号 p.
3686-3693
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The thermodynamic properties of quasi-two-dimensional Heisenberg antiferromagnet have been investigated in the framework of the modified spin-wave theory. A set of self-consistent equations is derived for chemical potential μ and two mean-field parameters, characterizing the nearest-neighbor spin correlations. Solving these equations under the condition μ=0, we derive a formula determining the Néel temperature
TN as a function of the coupling ratio ε≡
J⊥⁄
J⁄⁄ between the interplane and intraplane exchange couplings. In the region above
TN, the self-consistent equations have been solved numerically, to discuss the temperature dependence of the correlation length.
抄録全体を表示
-
Isao Harada, Mutsuko Fujikawa, Isao Mannari
1993 年 62 巻 10 号 p.
3694-3701
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Ground-state phase diagram and low-lying excitation spectrum of the one-dimensional
S=1 anisotropic Heisenberg antiferromagnetic chain with nearest neighbor and next nearest neighbor interactions are studied by means of an approximate mapping of the original
S=1 spin Hamiltonian to the effective fermion Hamiltonian, which describes the dynamics of spin zero defects in antiferromagnetic environments (domain walls in the Néel state). We find that the frustration due to the next nearest neighbor interactions works cooperatively with quantum fluctuation in the Haldane state and stabilizes it. This is naturally explained in terms of the spin zero defect. In addition, we discuss characteristic features of the excitation spectrum in connection with its ground-state properties.
抄録全体を表示
-
Yoji Ohashi
1993 年 62 巻 10 号 p.
3702-3709
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The uniform susceptibility of high-
Tc cuprates is studied by focusing on its anomalous temperature dependence. Our result shows that the uniform susceptibility has a temperature dependence due to the coupling with antiferromagnetic (AF) spin fluctuations. Furthermore, the difference of the temperature dependence between the lightly doped region and the overdoped region is explained with this mechanism as related to the strength of the AF spin fluctuations.
抄録全体を表示
-
Tadashi Shimizu, Haruyoshi Aoki, Hiroshi Yasuoka, Toshinobu Tsuda, Yut ...
1993 年 62 巻 10 号 p.
3710-3720
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The tensor components of the magnetic susceptibility (χ) and the Knight shift (
K) at the plane Cu(2) sites have been precisely measured in YBa
2Cu
3O
x with
x=6.98, 6.48 and 6.0. Using the temperature dependent χ and
K observed in YBa
2Cu
3O
6.48, we have carried out the analysis of
K-χ diagram to make a separation of the observed susceptibility into orbital and spin contributions. Assuming the orbital contribution from the Cu(2) ions is independent of
x for 6.0≤
x≤7.0, we have obtained the
x dependent spin susceptibility of the Cu(2) ions. The obtained spin susceptibility is discussed in comparison with the theoretical predictions of the Heisenberg model, the Stoner model and a band structure calculation. A complete set of the parameter values used in the crystal field model of a Cu
2+ ion (the crystal field splittings, the orbital reduction factor, the spin-orbit coupling and the
g-factors) has been determined from the
K-χ analysis.
抄録全体を表示
-
Takeo Jo, Shin Imada
1993 年 62 巻 10 号 p.
3721-3727
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
We give an interpretation for the observed systematic trend of magnetic circular dichroism (MCD) in L
2,3 photoabsorption of rare-earth (RE) atoms from Ce to Tm in ferro- or ferrimagnetic RE
2Co
17 assuming the 2
p→5
d electric dipole transition. We assume that the 4
f state of trivalent RE ions is in the polarized Hund-ground-state. We then take into account the spin and orbital magnetic moments induced in the RE 5
d state through the intraatomic 4
f-5
d exchange interaction approximated by a molecular field with assuming a band width of several eV and one tenth filling of the 5
d band. The integrated MCD intensity calculated with a naive one-electron picture is shown to correspond well to the observed trend. The 5
d orbital moment estimated both from the present model and from a MCD sum rule applied to the experiment is of the order of ∼0.1 μ
B, which is comparable to the 5
d spin moment.
抄録全体を表示
-
Nobuyuki Katoh, Masatoshi Imada
1993 年 62 巻 10 号 p.
3728-3740
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The ground state energy, the energy gap and the Fourier transform of the staggered spin correlation function
S(
Q) at zero temperature are investigated for the
S=1⁄2 antiferromagnetic Heisenberg model on a dimerized square lattice with the help of the spin-wave approximations, the second-order perturbation expansion and the quantum Monte Carlo simulations. In contrast to one-dimensional case, the spin gap appears above a finite critical value of the dimerization parameter. δ
c\simeq0.303, where the second-order transition takes place. The antiferromagnetic long range order exists below δ
c. The critical exponent of the order parameter in the antiferromagnetically ordered state is estimated by quantum Monte Carlo calculation to be \simeq(δ
c−δ)
β with β=0.27±0.04, while the correlation length in the spin gap region is scaled as \simeq(δ−δ
c)
−ν with ν=1.36±0.05. All of them are different from the estimates in one-dimension, ν=1 and the spin-wave approximation, β=ν=1. Possible relevance of our result for the spin gap behavior in high-
Tc superconductors is also discussed.
抄録全体を表示
-
Fumio Maruyama, Hiroyuki Nagai, Kengo Adachi
1993 年 62 巻 10 号 p.
3741-3750
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
The magnetic properties of Y
2(Co
1−xT
x)
14B (T=Mn, Fe, Ni) are studied by means of NMR and magnetic measurements. The substitution of Fe and Mn for Co in Y
2Co
14B affects the magnetic anisotropy with a spin reorientation from plane to axis. The relationships between the anisotropy changes and the hyperfine fields of
59Co nuclei determined by NMR are studied. The evaluated Co orbital moments and the increases of the hyperfine fields at 8
j1 and 8
j2 sites are larger than those at other sites, so Co at 8
j1 and 8
j2 sites give the large contribution to the anisotropy of the 3
d sublatice. These anisotropy changes are interpretted by the estimated local anisotropy energy per atom,
ES, at each site and the preferential substitution of Fe and Mn for Co at 8
j2 site.
抄録全体を表示
-
Mitsumasa Ishiwata
1993 年 62 巻 10 号 p.
3751-3761
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり
Selective spin inversion usually produces transfer of the longitudinal magnetization in a coupled spin system. Under irradiation of a stirring-field, however, transverse ones and multiple quantum coherences can also be simultaneously transferred in this process. For a coupled
13C–
1H spin system under irradiation resonant with one of the
1H lines,
13C tickling spectra are observed immediately after inversion of one component of the
13C-polarizations. Spectra thus obtained are considerably different from a simple selectively-inverted pattern of the steady-state ones. These changes depend on amplitude and frequency of the rf field, frequency and phase of the inversion pulse and inhomogeneity of the static magnetic field. The most prominent change in these spectra can be explained by transfer of zero quantum coherence, which is made in the differential form into each line of the spectra.
抄録全体を表示
-
Hiroharu Yorikawa, Masato Itenishi, Shinji Muramatsu
1993 年 62 巻 10 号 p.
3762-3763
発行日: 1993/10/15
公開日: 2007/05/29
ジャーナル
認証あり
-
Yoshinori Tsuchiya, Hideyuki Takita, Shigeyuki Murayama, Yoshikazu Ham ...
1993 年 62 巻 10 号 p.
3764-3765
発行日: 1993/10/15
公開日: 2007/06/01
ジャーナル
認証あり