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Hidetoshi Nishimori
1993 Volume 62 Issue 9 Pages
2973-2975
Published: September 15, 1993
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The conjecture of Ruján on error-correcting codes is proven. Errors in decoding of signals transmitted through noisy channels assume the smallest values when signals are decoded at a particular finite temperature. This finite-temperature decoding is compared with the conventional maximum likelihood decoding which corresponds to the
T=0 case. The method of gauge transformation in the spin glass theory is useful in this argument.
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Masayoshi Taguchi
1993 Volume 62 Issue 9 Pages
2976-2978
Published: September 15, 1993
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A poloidally and toroidally varying electrostatic potential due to the perpendicular ion drift and its effect on the radial heat flux are studied in the plateau regime for a nonaxisymmetric toroidal plasma. This potential produces an enhancement by one order of magnitude in the electron heat flux, whereas an increase of the ion heat flux is modest. Moreover, these radial electron and ion heat fluxes due to this potential are found to be
inward in a stellarator satisfying the conditions
mε
h2>2ε
t2 and
nq−
m>0, where
q is the safety factor,
n and
m are the numbers of the toroidal field periods and the helical field coils, and ε
t and ε
h are the toroidal and the helical magnetic field modulations.
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Toshiakira Ando, Akiyoshi Nagata, Shigeyuki Kubota, Ko-ichi Sato, Hide ...
1993 Volume 62 Issue 9 Pages
2979-2982
Published: September 15, 1993
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New features of dynamo action were found in normal-
Θ discharge on the STP-3M reversed-field pinch (RFP), where
Θ=
Bθ(
a)⁄〈
Bz〉 is the pinch parameter. The results indicate that as the magnetic Reynolds number (S) increases, the self-organization effect works smoother in the RFP plasma, hence the toroidal magnetic flux increases continuously and uniformly in the toroidal direction. Furthermore, the effective inductance in the RFP plasma increases with increasing
S and is kept constant during the plasma current duration. These features lead to the conclusion that usual discrete dynamo action does not play an essential role in the RFP dynamo.
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Tomoyuki Hikita, Hidetoshi Dainobu
1993 Volume 62 Issue 9 Pages
2983-2985
Published: September 15, 1993
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Longitudinal acoustic phonons were excited by crossing two picosecond pulse laser beams in Rocbelle salt. The time dependence of phonon oscillation was detected by the time-delayed third probing beam. From the recorded signals for three crossing angles, the phonon frequencies were deduced to be 1.57 GHz, 1.12 GHz and 506 MHz. The results indicate that the thermal absorption process (ISTS) is predominant for the present impulsive stimulated scattering.
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Tatsuo Suzuki, Tsuneya Ando
1993 Volume 62 Issue 9 Pages
2986-2989
Published: September 15, 1993
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A self-consistent calculation is performed for the study of magnetic-field effects on the energy level structure of quantum wires formed by a split gate technique at GaAs/AlGaAs heterostructures. The self-consistent potential and the energy dispersion exhibit a dramatic change when a subband depopulation occurs in high magnetic fields.
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Daijiro Yoshioka, Masao Ogata
1993 Volume 62 Issue 9 Pages
2990-2993
Published: September 15, 1993
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An asymptotically exact ground-state wave function is obtained for one-dimensional electrons of a model Hamiltonian. The Hamiltonian has an arbitrary parameter. Tomonaga-Luttinger (TL)-liquid-like behavior for a small value of the parameter changes gradually into non-TL-liquid behavior as the parameter is increased. Parameter dependence of the momentum distribution function and the structure factor are investigated numerically for small systems.
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Masahito Ueda, Akira Shimizu
1993 Volume 62 Issue 9 Pages
2994-2998
Published: September 15, 1993
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We study the noise spectrum of electrical current in a voltage-biased conductor. At low frequencies, the noise power in a nondissipative conductor is below the standard quantum limit which typically appears in tunnel junctions. Energy dissipation in the conductor further reduces the low-frequency noise power, nearly to zero when the dissipation is strong enough. At high frequencies, however, the noise is no longer suppressed, and the noise power approaches the standard quantum limit irrespective of the strength of energy dissipation.
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Yositake Takane
1993 Volume 62 Issue 9 Pages
2999-3002
Published: September 15, 1993
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Quasiparticle energy dispersions in the vortex state of pure type-II superconductors are studied theoretically near
Hc2, taking account of the orbital quantization due to a magnetic field. We find that the dispersions have a small gap at integer multiples of cyclotron frequency. It is shown that the quasiparticle is composed of a pair of an electron and a hole quantized in Landau levels.
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Yasuhiro Nakazawa, Masayasu Ishikawa, Satoru Noguchi, Kiichi Okuda
1993 Volume 62 Issue 9 Pages
3003-3006
Published: September 15, 1993
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We investigated two intermetallic compounds, CeZn
11 and UZn
12, for heavy-electron behavior and found that the coefficient of low-temperature specific heat is about 850∼900 mJ/(mol K
2) for UZn
12. The compound CeZn
11, which has a relatively small γ value of 43.2 mJ/(mol K
2), exhibited an antiferromagnetic long-range order at 2.0 K evidenced by a large peak of the specific heat and a broad maximum in the susceptibility, while UZn
12 exhibited neither superconducting nor magnetic phase transition down to 0.4 K.
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Takayuki Shirakura, Fumitaka Matsubara
1993 Volume 62 Issue 9 Pages
3007-3010
Published: September 15, 1993
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We study a short-range site-random Ising model in three dimensions (3D) using a Monte Carlo (MC) method and find a phase transition to a spin glass (SG) phase at a very high temperature (
Tc\simeq2.83 J). Values of the critical exponents estimated from a finite-size scaling analysis are different from those in both the 3D\mp
J Ising model and the 3D Ising ferromagnet. We suggest that the SG phase in this model is a new SG phase which is characterized by a nonzero SG order parameter
q≠0.
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Hitoshi Ohta, Seisaku Imagawa, Mitsuhiro Motokawa, Hidekazu Tanaka
1993 Volume 62 Issue 9 Pages
3011-3014
Published: September 15, 1993
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Submillimeter wave ESR has been performed from 90 to 380 GHz for CsCuCl
3 using the pulsed magnetic fields up to 15 T in the temperature range from 1.8 to 86 K. In the ordered phase below
TN=10.5 K, shift of the ESR mode from that in the conventional mean field theory including Dzyaloshinsky-Moriya interaction has been observed for
H⁄⁄
c above the critical field
Hc where a small jump in the magnetization occurs. These anomalies cannot be understood in terms of the mean field theory and will be discussed in connection with a new theory proposed by Shiba and Nikuni which suggests that the quantum effect is responsible for the anomalies at
Hc.
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Masayasu Takeda, Yasuo Endoh, Hideki Yasuda, Kazuyoshi Yamada, Atsushi ...
1993 Volume 62 Issue 9 Pages
3015-3018
Published: September 15, 1993
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We have investigated Fe/Cr artificial multilayers to elucidate the origin of a giant magnetoresistance effect (GMR), by neutron scattering measurement in external magnetic fields up to 0.8 Tesla. Intense diffuse scattering appears around the superlattice reflection corresponding to the antiferromagnetic Fe layer stacking. The magnetic diffuse scattering intensity decreases drastically in magnetic fields, which strongly suggests that the GMR effect in this system is dominated by the appearance of magnetic disorder at the interface between the Fe and the Cr layers.
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Masakazu Ito, Hiroyuki Deguchi, Kazuyoshi Takeda, Yuzo Hashimoto
1993 Volume 62 Issue 9 Pages
3019-3022
Published: September 15, 1993
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The fully mapped
T-
H (temperature-magnetic field) phase diagram of DyNi
2Si
2 has been determined by heat capacity and magnetic susceptibility measurements. In zero magnetic fields, the heat capacity exhibits a small but distinct cusp at
T1=3.7 K corresponding to the magnetic order-order phase transition, and a clear λ-type transition at
TN=5.6 K. Except for the paramagnetic phase, three magnetic phases are found below
TN and below the critical field
Hc=21.5 Oe. The results are discussed in comparison with recent experimental evidence which indicates the two-dimensionally modulated spin structures in the
c-plane.
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Tetsuo Ohama, Hiroshi Yasuoka, Yasuomi Maeda, Toshiro Takabatake, Hiro ...
1993 Volume 62 Issue 9 Pages
3023-3026
Published: September 15, 1993
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NMR and NQR measurements have been made for Pauli paramagnetic UNi
2Ga. The temperature dependence of the Knight shift and the nuclear relaxation rate 1⁄
T1 at the Ga sites has been measured between 4.2 K and 290 K. Fermi liquid behavior, that is, temperature-independent Knight shift and 1⁄
T1 proportional to temperature, has been observed over the measured temperature range. A quantitative analysis suggests that the enhancement of the wave-vector-dependent susceptibility χ(
q) is fairly localized near
q∼0 in
q space.
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T\={o}ru Ozaki, Takashi Senju, Eiji Nakamura
1993 Volume 62 Issue 9 Pages
3027-3030
Published: September 15, 1993
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Detailed structures of the ferroelectric domains in KH
2PO
4 have been observed between parallel polarizers. Three types of domain patterns which show self-similarity are found in the pyramidal growth sectors of
c plate crystals. The patterns are characterized with fractal aspects of the “pentad” Cantor sets having the Hausdorff dimension
D≈0.756.
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Baoping Zhang, Satoru S. Kano, Yasuhiro Shiraki, Ryoichi Ito
1993 Volume 62 Issue 9 Pages
3031-3034
Published: September 15, 1993
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The oscillator strength of excitons in InGaAs/GaAs single quantum wells is studied for the first time by reflectance measurements using a Fourier transform spectrometer. Decrease of the oscillator strength of the zero phonon line at higher temperatures is found and analyzed using the temperature dependence of a modified Debye-Waller factor with an averaged phonon mode. For a sample of
L=140 Å, the oscillator strength is estimated to be 5.1×10
−4 Å
−2. The well width dependence of the oscillator strength is found to reach a maximum at a critical well width. We also observe anomalies in the oscillator strength and linewidth at temperatures lower than 50 K.
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Hideaki Ujino, Miki Wadati, Kazuhiro Hikami
1993 Volume 62 Issue 9 Pages
3035-3043
Published: September 15, 1993
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For the quantum Calogero-Moser model, we construct a set of conserved operators and another set of operators, named boost operators, from its Lax operator. We prove that each conserved operator satisfies both the Lax equation and a remarkable relation named additional relation. From these knowledge, we show that the conserved operators are involutive. Moreover, the conserved operators and the boost operators constitute the U(1)-current algebra. All the proofs are simplified a great deal due to the Lax equations and additional relations.
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Nobuko Fuchikami, Sho Kaneda, Shunya Ishioka
1993 Volume 62 Issue 9 Pages
3044-3051
Published: September 15, 1993
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We propose a stochastic model of phonon-number fluctuations that allows to simulate 1⁄
f-like behavior. The fluctuation process is described as a random walk on the ladder of energy levels of a harmonic oscillator. Two characteristic time scales are involved in the process: the mean life time of states τ
l and the correlation time τ
c. When the ratio τ
c⁄τ
l is large, the 1⁄
f-like spectrum is observed within the frequency range 1⁄τ
c<
f<1⁄τ
l. Conditions for large values of the ratio are discussed.
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Macoto Kikuchi, Nobuyasu Ito
1993 Volume 62 Issue 9 Pages
3052-3061
Published: September 15, 1993
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A new method for studying dynamical correlation of temporal sequence is proposed. We introduce a new quantity named
statistical dependence time τ
dep as an estimator for the equilibrium relaxation time. The calculation of τ
dep does not require calculation of any time-displaced correlation function nor numerical fitting in extracting the relaxation time; as a result, the estimation of τ
dep and statistical analysis such as the error estimation are quite straightforward and simple. We apply this method to the critical dynamics of 3D Ising model, and estimate the dynamical critical exponent
z as 2.030±0.004, provided
Kc=0.221654 (if possible error in
Kc is taken into account, the error in
z becomes 0.01).
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Tota Nakamura, Naomichi Hatano
1993 Volume 62 Issue 9 Pages
3062-3070
Published: September 15, 1993
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The Néel and collinear order parameters of the
J1-
J2 model are calculated by the quantum Monte Carlo simulation with the reweighting method. Systems of sizes
N=4×4, 4×8 and 8×8 are treated. The thermodynamic quantities obtained by the size extrapolation suggest that the Néel order remains finite for α≤0.4 and vanishes for α>0.6, where α is defined by
J2⁄
J1, and that the collinear order remains for α≥0.7 and vanishes for α<0.6. The present result is consistent with the result of the modified spin-wave calculation, conflicting with that of the naive spin-wave theory.
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Igor I. Gancheryonok, Takashi Kushida
1993 Volume 62 Issue 9 Pages
3071-3076
Published: September 15, 1993
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A theoretical analysis is made of polarization characteristics of three-wave sum (ω
3=2ω
1+ω
2) and difference (ω
3=2ω
1−ω
2) frequency mixing or CARS in isotropic substances. A formula to calculate the polarization state of the combined wave at frequency ω
3 is obtained for the general case of noncollinear pump (ω
1) and probe (ω
2) beams. The conditions are also clarified in which the generated radiation has the same polarization state or the polarization state with the opposite handedness as the input probe beam. The results are compared with a recent experiment of three-wave difference frequency mixing in Hg vapor. Determination of spectroscopic parameters by the application of ellipsometric method to the three-wave mixing is also discussed.
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Noboru Takimoto, Shinzi Yamamura, Kunio Funayama
1993 Volume 62 Issue 9 Pages
3077-3091
Published: September 15, 1993
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Experimental study is given of non-equilibrium stationary 1⁄
f temperature noise. A previous theory predicts that one-dimensional or quasi one-dimensional thermal conductor generates, under proper conditions, the 1⁄
f temperature noise, when input heat fluctuates with a white spectrum. The prediction is confirmed by experiments on a thin and long enough cylindrical copper. In passing it is shown explicitly that this noise is related to a time-scale invariant relaxation.
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Kenji Tanaka, Keiji Matsuo, Shinji Koda, Mark Bowden, Katsunori Muraok ...
1993 Volume 62 Issue 9 Pages
3092-3105
Published: September 15, 1993
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Electron density fluctuations in Heliotron E were measured using a wide beam laser phase contrast method in a frequency range of 2.5≤
f≤500 kHz and a wavenumber range of 0.1≤
k≤1.3 rad/mm. Two branches of
S(
k,
f) spectra were detected, which we have called a high speed branch and a low speed branch because of a difference in their measured phase velocities. Their characteristics were studied from spatial distributions, correlation with magnetic fluctuations, phase velocities, fluctuation levels and theoretical considerations. The high speed branch is consistent with a Magneto Hydro Dynamic (MHD) mode driven by a resistive interchange instability and mainly existed inside the limiter, and the low speed branch is explained as a microturbulence driven by a drift instability and mainly existed outside the limiter. The implications of these findings for studies of plasma confinement in Heliotron E are discussed.
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Masayasu Sato, Shinich Ishida, Nobuaki Isei
1993 Volume 62 Issue 9 Pages
3106-3113
Published: September 15, 1993
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The effects of relativistic frequency broadening on the ECE measurements for a high temperature tenuous tokamak plasma are studied. Calculations of the radiation transfer are carried out assuming a spherically-symmetric relativistic Maxwellian distribution function for electrons. From the relativistic point of view, observation of the fundamental ordinary mode ECE along a major radius from the low field side is best for the measurement of the electron temperature profile. It is impossible to obtain the electron temperature profile using measurements from the high field side without information on the optical thickness along the propagation path.
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Yoshio Nogami, Kazuyoshi Ogasawara, Shigeki Takeuchi, Takehiko Ishigur ...
1993 Volume 62 Issue 9 Pages
3114-3126
Published: September 15, 1993
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Structures of Langmuir-Blodgett (LB) superlattice films formed with alternately deposited fatty acid Cd salts with different alkyl-chain length are studied by high resolution X-ray diffraction method using a synchrotron radiation source. The remarkable diffraction peak shift is observed in the superlattice film. The shift is interpreted in terms of the Guinier effect in partially-disordered superlattice system. Simultaneous modulation of molecular position and of molecular scattering factor results in the peak shift. The effect of alkyl-chain species substitution and of cooling on the peak shift are also described. The partial disorder in the superlattice is caused by dissolution of LB film.
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Takashi Sakuma, John O. Thomas
1993 Volume 62 Issue 9 Pages
3127-3134
Published: September 15, 1993
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The diffuse neutron scattering intensity for Li
2SO
4 at 908 K has been calculated using a treatment which includes correlation between thermal displacements of the atoms and reorientation of the SO
42− ions. The calculation of the diffuse neutron diffraction scattering for Li
2SO
4 powder is based on a structural model obtained from a recent analysis of single crystal neutron Bragg reflections for the high temperature cubic phase of Li
2SO
4. Relatively large correlations are required between the displacements of the atoms (λ
s(S)s(O) and λ
sn(O)sn′(O) for
n≠
n′) to obtain good agreement between calculated and observed diffuse intensities. It is shown that evidence for a “paddle-wheel mechanism” is difficult to obtain from an analysis of the diffuse neutron scattering intensities.
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Kazuo Nakamura, Shoji Kashida
1993 Volume 62 Issue 9 Pages
3135-3141
Published: September 15, 1993
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TlS is known as a mixed valence compound containing monovalent and trivalent thallium ions. The structure of the newly found monoclinic TlS has been analyzed using three-dimensional single crystal diffraction data. Space group C2:
a=11.018(6),
b=11.039(15),
c=60.16(7) Å, β=100.69°(4) and
Z=128. The structure is characterized by layers formed of corner-connected Tl
+3S
4 tetrahedra. Monovalent Tl
1+ ions are located between the layers and have trigonal prismatic coordination of the sulfur ions. The structure is a variation of the TlGaSe
2 type with fourfold modulation along the
c-axis. The modulation is caused by cooperative distortion of trigonal prisms around the monovalent Tl
1+ ions.
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Masanori Inui, Shin’ichi Takeda, Tetsuo Uechi
1993 Volume 62 Issue 9 Pages
3142-3149
Published: September 15, 1993
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The ultrasonic velocity, sound attenuation and density measurements have been carried out for molten Cu(Cl
1−xBr
x) mixtures at temperatures from the melting points to about 800°C to investigate the thermodynamic and dynamical properties. The adiabatic compressibility of this system has obtained from the observed ultrasonic velocity and density. The observed compressibility has an interesting concentration dependence of positive deviation from linear one and has the maximum around Cu(Cl
0.2Br
0.8), which suggests large fluctuations in the molten mixtures compared with pure molten CuCl and CuBr. The sound attenuation shows large temperature dependence around
x=0.2 and 0.8. We discuss the thermodynamic and dynamical properties of the molten mixtures from a view point of chemical bond, taking the difference of ionicity between Cl and Br into account.
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Shun-iti Ezure, Toshio Ikeda
1993 Volume 62 Issue 9 Pages
3150-3156
Published: September 15, 1993
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Diffusion measurements have been made for Cl
2 in NaCl and RbCl crystals doped with OH
− ions. Diffusion front was detected by observing the blue coloration with electron irradiation or the yellow fluorescence due to O
2− ions. The solution of the diffusion equation with a chemical reaction permits the evaluations of diffusion coefficient and Henry’s constant of Cl
2 in these crystals. Activation energies of the diffusion are 1.61±0.11 eV with
D0=5.8×10
−5 m
2 s
−1 in NaCl and 1.84±0.24 eV with
D0=7.1×10
−2 m
2 s
−1 in RbCl. These results are compared with theoretical results by Diller. Temperature dependence of the Henry’s constant indicates that dissolution of Cl
2 molecules at the surface is the exothermic reaction.
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Haruyoshi Aoki, Shinya Uji, Ariane Keiko Albessard, Yoshichika \={O}nu ...
1993 Volume 62 Issue 9 Pages
3157-3171
Published: September 15, 1993
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The de Haas-van Alphen (dHvA) effect measurements have been performed for both the field ranges above and below the metamagnetic transition field (
Hm) in the (010) plane in CeRu
2Si
2. The experimental frequencies and effective masses below
Hm agree well with the predictions of the first principle or the renormalized band structure calculations based on the itinerant 4f electron model. On the other hand, those above
Hm can be explained well by the localized 4f electron model. The one to one correspondence between the dHvA oscillations below and above
Hm can be made. The frequencies are found to change abruptly around
Hm. The effective masses decrease considerably around
Hm and continue to decrease with increasing field. These observations indicate that the 4f electron nature changes from itinerant to localized around
Hm.
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Takao Mori, Yoshihiro Shimazu, Seiichiro Ikehata
1993 Volume 62 Issue 9 Pages
3172-3180
Published: September 15, 1993
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We investigated the effect of compensation on the electronic properties of heavily phosphorus doped silicon. A sample just in the metallic region was compensated by irradiation with fast neutrons to the intermediate region. A detailed study of
29Si NMR (Knight shift, spin-lattice relaxation time
T1) was carried out together with a measurement of the static magnetic susceptibility. We obtained the result that in our compensated samples the Knight shift becomes larger than in the uncompensated case. Coupled with results of
T1 and magnetic susceptibility we conclude that as a result of compensation the donor wave function extends spatially. The NMR measurements were made in the temperature region of 0.5–0.04 K.
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Osamu Sakai, Yukihiro Shimizu, Hiroyuki Shiba, Koji Satori
1993 Volume 62 Issue 9 Pages
3181-3197
Published: September 15, 1993
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The Kondo problem in superconductors is studied by extending Wilson’s numerical renormalization group method. As a continuation to a previous paper (J. Phys. Soc. Jpn.
61 (1992) 3239), various problems related to the localized excited state produced by a magnetic impurity are examined in detail. In particular, the binding energy of the localized excited state, its spectral weight, one-electron and magnetic excitation spectra and the spatial variation of the order parameter are studied over the whole regime of the magnitude of
TK⁄
Δ (
TK: Kondo temperature,
Δ: superconducting energy gap).
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Daijiro Yoshioka
1993 Volume 62 Issue 9 Pages
3198-3202
Published: September 15, 1993
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Orbital magnetization of two-dimensional electrons confined in a harmonic potential is calculated at finite temperature. The calculation has been done with the canonical ensemble average, and the results are compared with those by the grand canonical averaging. Both methods give the same results, the Landau diamagnetism, for
kBT>hω
0, where ω
0 is the frequency of the harmonic potential. At lower temperature both averaging give qualitatively similar results except that the canonical averaging gives slightly larger magnetic response than the grand canonical averaging.
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Hiroshi Shimada, Taizo Masumi
1993 Volume 62 Issue 9 Pages
3203-3215
Published: September 15, 1993
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Transport phenomena of photoexcited electrons in CdS have been investigated at crossed electric and magnetic fields. Dynamics of electrons at the so-called “accumulation” area in the velocity space, escaping from the LO-phonon emission, has been clarified in a view of the hot electron effect at strong transverse magnetic fields, particularly in the case of interaction with acoustic phonons, both the deformation-potential coupling and piezoelectric coupling included.
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Kazushige Machida, Tetsuo Ohmi, Masa-aki Ozaki
1993 Volume 62 Issue 9 Pages
3216-3230
Published: September 15, 1993
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Double superconducting transitions and the observed isotropy of the phase diagram; magnetic field (
H) vs temperature (
T) in a heavy Fermion compound UPt
3, are consistently accounted for by a scenario based on the one-dimensional representation (1D scenario) with odd-parity in the weak spin-orbit coupling case. A symmetry breaking field due to the antiferromagnetism (
TN=5 K) lifts the spin space degeneracy of the pairing function to split the transition temperature
Tc. The 1D scenario scenario explains the experiments better than the previous 2D scenario based on the two-dimensional representation. The identified triplet pairing function of the B phase in low
T and low
H is characterized not only by time inversion breaking, but also by non-unitarity. In addition to the usual excitation branch with the line node, the existence of the gapless excitation branch in this state explains various long known puzzles, in particular, the “residual” linear specific heat at low
T.
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Guoxiang Huang, Zaixin Xu, Wenliu Xu
1993 Volume 62 Issue 9 Pages
3231-3238
Published: September 15, 1993
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A magnetic gap soliton theory for the intrinsic self-localized magnon modes in one-dimensional Heisenberg antiferromagnets is developed in this paper. It is shown that these solitons have zero group velocity in the magnetic lattice and that the frequency of carrier wave is within the gap of magnon band. Different from the results obtained recently by lattice Green’s function, our approach demonstrates that only the antisymmetric two-spin bound state can exist. We also show that the system can produce a new type of intrinsic self-localized magnon mode, a nonpropagating kink, whose oscillatory frequency is just below the upper cut-off of the magnon band.
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Tatsuo Kobayashi, Masafumi Takiguchi, Kiichi Amaya, Hiroyuki Sugimoto, ...
1993 Volume 62 Issue 9 Pages
3239-3243
Published: September 15, 1993
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The magnetic properties of MOTMP 4-methacryloyloxy-2,2,6,6-tetramethyl-piperidin-1-oxyl are studied at tempratures below 1 K. The dominant magnetic coupling between the radicals is ferromagnetic. The one-dimensional behavior observed in the temperature dependence of susceptibility is consistent with previous result of heat capacity measurement in which the intrachain ferromagnetic interaction is estimated to be
J⁄
k=0.9 K. The susceptibility in the ordered state, however, shows spin-flip transition, which reveals antiferromagnetic long range order. From the analysis of ordering temperature
TN and critical field
HC, the interchain interactions are also estimated by the mean field theory.
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Yoshikazu Suzumura, Yoshiaki \={O}no
1993 Volume 62 Issue 9 Pages
3244-3256
Published: September 15, 1993
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Organic conductors, DCNQI-Cu salts, with a mixed valence Cu
+4⁄3 on the average has been studied theoretically by applying the slave-boson method to the strongly correlated systems which consist of π-electrons of DCNQI molecule and d-electrons of Cu atoms. The ground state is calculated by use of the 1/
Nσ expansion method which treats the local constraint strictly. It is shown that the electron mass around the Fermi surface is enhanced in the presence of the charge density with the three-fold periodicity.
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Hiroyasu Shimaoka, Kazuhiro Kuboki
1993 Volume 62 Issue 9 Pages
3257-3265
Published: September 15, 1993
Released on J-STAGE: June 01, 2007
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The one-dimensional
S=1 anisotropic antiferromagnetic Heisenberg model with next-nearest as well as nearest-neighbor exchange intearction is studied with particular emphasis on the effect of the frustration. The ground-state phase diagram and the low-lying excitations are examined by use of the bosonization method and the self-consistent harmonic approximation. It turns out that the frustration works in stabilizing the Haldane phase against the Neel phase, since its effect on the latter phase is larger. The large-
D phase is almost unaffected by the frustration, resulting in its relative stability against other phases. The excitation gap in the Haldane phase (Haldane gap) is found to be reduced by the frustration near the boundary to the large-
D phase, while it increases in the vicinity of the Neel phase.
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Hidetoshi Nishimori, Hikaru Kawamura
1993 Volume 62 Issue 9 Pages
3266-3267
Published: September 15, 1993
Released on J-STAGE: May 29, 2007
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We prove that there is no gauge glass ordering in two dimensions at finite temperatures. Numerical results have thus been rigorously justified.
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Tetsuro Nikuni, Hiroyuki Shiba
1993 Volume 62 Issue 9 Pages
3268-3276
Published: September 15, 1993
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A theoretical interpretation is given on the magnetization process of CsCuCl
3 showing a small jump for the external field applied parallel to the
c-axis. It is shown that quantum fluctuations are so important in this
S=1⁄2 triangular antiferromagnet that they can change the ground-state spin structure. The observed magnetization jump is successfully explained as a spin flop process caused by the quantum effect.
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Tomonobu Ohyama, Hiroyuki Shiba
1993 Volume 62 Issue 9 Pages
3277-3293
Published: September 15, 1993
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Recent neutron experiments have revealed that the excitation spectrum in quasi-one-dimensional ABX
3-type antiferromagnets cannot be explained within the conventional linear-spin-wave theory even in the ordered phase. To explain this result, we take into account two-magnon excitation processes in the spin-wave expansion and apply it to CsNiCl
3 at
T=0. We find that in addition to modifying the energy and intensity of the one-magnon spectrum, these processes can result in large peaks due to two-magnon continuum. The coupling between longitudinal and transverse fluctuations is found to be important as previously suggested by phenomenological Landau-Ginzburg models. Our results agree reasonably well with available experiments. Similar effects can be expected in other quasi-one-dimensional systems having non-collinear spin structures.
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Jiang-Tsu Yu, Ssu-Hao Lou
1993 Volume 62 Issue 9 Pages
3294-3301
Published: September 15, 1993
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The CrO
42− impurity has been found to be very effective in stabilizing a phosphorus oxyradical produced by γ-irradiation at room temperature in KH
2PO
4 and NH
4H
2PO
4 crystals. A similar radical species can be observed in pure Ba(H
2PO
4)
2 crystals γ-irradiated at room temperature. The observed principal values of the
g-factor and the
31P hyperfine splitting indicate that this radical species could be the [PO
5]
2− or [O
3POO]
2−.
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Katsurou Hanzawa
1993 Volume 62 Issue 9 Pages
3302-3314
Published: September 15, 1993
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Electronic configurations and local susceptibilities at all copper and oxygen sites in YBa
2Cu
3O
7 are determined from the analysis of the electric field gradients (EFG’s) and the Knight shifts (shifts). Besides main contributions from 3
d holes for Cu sites and 2
pσ holes for O sites, it is necessary to consider 4
p electrons of Cu and 2
pπ holes of O for accurate analysis of the EFG’s, and 4
s electrons of Cu and 2
s holes of O for the shifts. Difference in the observed EFG’s between Cu(1) and Cu(2) is due to the 4
p-electron contributions, and the 3
d-electron states are determined to be quite similar. Each site of Cu and O shares almost same amount of holes. The local spin susceptibilities, however, are fairly different in order of magnitude as Cu(2), Cu(1), O(2, 3), O(4), implying a strong correlation in Cu(2).
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Makoto Iwata, Masahito Eguchi, Yoshihiro Ishibashi, Shigeo Sasaki, Hir ...
1993 Volume 62 Issue 9 Pages
3315-3326
Published: September 15, 1993
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The successive phase transitions in (CH
3NH
3)
3Bi
2Br
9 (MABB) single crystal have been investigated by measuring of dielectric and elastic dispersion and Brillouin and Raman scattering. Softening of the elastic constant
c66 and critical slowing down of the order parameter, which belongs to the
Eg representation, have been found in the phase I. No optical soft mode has been observed. The phase transition from the phase I to the phase II has been discussed by the Landau theory.
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Akito Kakizaki, Toyohiko Kinoshita, Takehiko Ishii, Takayuki Kashiwaku ...
1993 Volume 62 Issue 9 Pages
3327-3333
Published: September 15, 1993
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In the valence band photoemission spectra of CeNi single crystals, we have observed a new satellite feature which appears at the lower binding energy side of the two-hole bound state satellite and shows resonance enhancement at the Ni 3
p threshold. On the basis of the observed excitation energy dependences of the spectral features, we investigate the origin and the resonance aspect of this new feature. We also investigate the origin of the other weak valence band satellites which appear at 5.3 eV and 10.6 eV.
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C. D. Hu
1993 Volume 62 Issue 9 Pages
3334-3342
Published: September 15, 1993
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We have analysed the nonlinear current excited by the
s-polarized incident light on jellium surfaces with quantum mechanics. The microscopic structure of the surface is also taken into account. We found that the current density is proprotional to ∇
E2. The proportional coefficient is related to the linear density-current response function of the jellium surface.
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Alain Ferragut, Yasuyuki Gono, Takeshi Murakami, Tsuneyasu Morikawa, Y ...
1993 Volume 62 Issue 9 Pages
3343-3344
Published: September 15, 1993
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Iwao Hosokawa
1993 Volume 62 Issue 9 Pages
3345-3346
Published: September 15, 1993
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Iwao Hosokawa
1993 Volume 62 Issue 9 Pages
3347-3348
Published: September 15, 1993
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