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Volume 62, Issue 4
Displaying 1-47 of 47 articles from this issue
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Kiyoshi Sogo1993 Volume 62 Issue 4 Pages 1081-1084
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe numerical algorithm for computing eigenvalues of a given matrix using the Toda molecule equation, suggested recently by Hirota, Tsujimoto and Imai, is shown to be equivalent to the quotient-difference method. This relation, convergence of the algorithm and extension to a much wider range of matrices are described.View full abstractDownload PDF (427K) -
Takashi Nagatani1993 Volume 62 Issue 4 Pages 1085-1088
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA cellular automaton (CA) model is presented to simulate the traffic jam induced by a traffic accident. The spreading of jamming cars induced by a car crash is investigated by computer simulation. An analogy is proposed between the crystal growth and the traffic-jam spreading. The scaling behavior of the traffic-jam spreading is studied. It is shown that the number N of jamming cars scales as N≈t2.34±0.03 for p above the dynamical jamming transition pc=0.35 and N≈t1.07 below pc where t is the time and p is the density of cars. The time constant ts, which is the time required for all cars to stop, scales as ts≈p−1.07±0.03 for p<pc. The following scaling form is found: p−1N≈(p1.07t)1.07 for p<pc.View full abstractDownload PDF (443K) -
Chikako Uchiyama, Fumiaki Shibata1993 Volume 62 Issue 4 Pages 1089-1092
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA microscopic laser equation is solved rigorously. In order to transform the original equation of the density matrix into a more tractable partial differential equation, spin and boson coherent states are used. The resulting equation for the probability density is solved to give a continued fraction with the use of orthogonal polynomials. As a preliminary result, dynamics of certain physical quantities are calculated.View full abstractDownload PDF (321K) -
Nobuhito Ohno, David J. Lockwood, Kiyoshi Deguchi, Armin Fuith, Hans W ...1993 Volume 62 Issue 4 Pages 1093-1096
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe effect of growth conditions on the structural acentricity in PbHPO4 has been studied as a function of temperature from 295 to 365 K (TC=310 K) by monitoring the intensities of several odd-parity Raman lines. Only a small acentricity was detected for temperatures just above TC, and the result was independent of sample growth temperature (above and below TC) and conditions.View full abstractDownload PDF (550K) -
Seiji Kojima, Shinichi Hamazaki, Masayuki Tsukioka, Masaaki Takashige1993 Volume 62 Issue 4 Pages 1097-1100
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe concentration dependences of ferroelectricity and ferroelasticity of Ba2NaNb5(1−x)Ta5xO15 were studied by Raman spectroscopy. The A1(z) mode spectra clearly show the difference between ferro- and paraelectric phases. With the increase of x starting from 0.1, the A1(z) modes at 278, 640 cm−1 and at x=0.1 show softening below x=0.7, and then become higher above x=0.7. It is concluded that the ferroelectric phase becomes a paraelectric one at a concentration between x=0.6 and 0.7. With regard to the ferroelasticity the B2(y) mode at 32 cm−1, which is coupled to the ferroelasticity, was investigated. When the concentration x increases the mode at 32 cm−1 fades and then disappears at a concentration around x=0.9. This strongly suggests that the ferroelastic phase disappears around the concentration of 0.9.View full abstractDownload PDF (499K) -
Kohji Abe, Gérard Dolino1993 Volume 62 Issue 4 Pages 1101-1104
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSNew observations of the memory effect in the incommensurate phase of quartz have been performed with birefringence measurements. The enhancement and the decay of the memory effect have been measured for various writing times. A linear relationship between the decay time and the writing time has been found, which cannot be explained by the usual diffusion model of the memory effect. We also present the first observation of a memory effect in a light scattering experiment.View full abstractDownload PDF (555K) -
Masatoshi Imada1993 Volume 62 Issue 4 Pages 1105-1108
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSOne type of Mott transition (MT1) is characterized by diverging enhancement of the charge effective mass when one approaches a Mott insulator from the side of the paramagnetic metal. Another fundamentally different type of Mott transition (MT2) is shown to exist when a spin gap opens. The linear coefficient of the specific heat γ decreases and then vanishes at the transition point of MT2 in sharp contrast with MT1. As an example, a dimerized t-J model is shown to undergo MT2. The underlying pairing mechanism determines the character of MT2. Recent controversial experimental results on the Mott transitions in copper oxides and other strongly correlated systems are discussed from the above viewpoint.View full abstractDownload PDF (588K) -
Hidetoshi Fukuyama, Hiroshi Kohno, Ry\={o}en Shirasaki1993 Volume 62 Issue 4 Pages 1109-1113
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSEffects of long-range Coulomb interaction on the temperature dependence of the resistivity due to impurity scattering have been investigated for a single-channel quantum wire. The resistivity is seen to diverge as T→0, as in the case of the Luttinger liquid with interaction constants independent of momentum transfer, but in the present case, the effective value of the exponent itself depends on T reflecting the logarithmic momentum dependence of the long-range interaction.View full abstractDownload PDF (512K) -
Kazuyoshi Yoshimura, Hiroshi Kubota, Hiroshi Tanaka, Yumiko Date, Mako ...1993 Volume 62 Issue 4 Pages 1114-1117
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSCompositional phase separation was observed in La2−xBaxCuOy near the optimum composition (x∼0.16) for superconductivity with a decisive miscibility gap by means of X-ray diffraction measurements. The phase-separated samples do not show intrinsic superconductivity. Therefore, the superconductive compound in this system is not in a chemical equilibrium state at low temperatures, but is a high-temperature phase obtained by quenching to room temperature. The critical temperature of the phase separation Tp takes a maximum value of 950°C at x∼0.16, suggesting that phase instability is crucial for high-Tc superconductors. The end composition of the miscibility gap in the Ba-poor composition region was found to be 0.12, which is a singular point from crystallographic and band structural standpoints.View full abstractDownload PDF (651K) -
Arata Tanaka, Takeo Jo1993 Volume 62 Issue 4 Pages 1118-1122
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSWe discuss the spin polarization of resonant 3d photoemission spectra at the Ni 3p threshold for ferromagnetic Ni from the viewpoint of a many-body configuration interaction, on the basis of the Anderson impurity model including atomic multiplets. The calculated relative spin polarization (majority-spin minus minority-spin divided by their sum) at the 6-eV satellite is shown to exhibit a dip structure with a minimum of ∼20% and a maximum of ∼35% separated by 7∼8 eV near on-resonance as a function of incident photon energy, which is consistent with the results of recent experiment. Its structure is, contrary to previous discussions, shown to be caused not only by the Fano interference effect but also by the 3p-3d exchange and 3p spin-orbit interaction in the intermediate state of the second-order resonant process. The spin polarization in the main peak and in the various positions of satellites is also discussed.View full abstractDownload PDF (692K) -
Kiyohide Nomura, Kiyomi Okamoto1993 Volume 62 Issue 4 Pages 1123-1126
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWe numerically investigate the critical lines of the fluid-dimer and the Néel-dimer transitions of the S=1⁄2 antiferromagnetic XXZ chain with next-nearest interactions, assuming the asymptotic behavior to be determined by the quantum sine-Gordon model. Our result is different from that of Tonegawa, Harada and Kaburagi, who used the phenomenological renormalization group (PRG). We show that the PRG may lead to a false critical point when it is applied to the Kosterlitz-Thouless-type transition.View full abstractDownload PDF (496K) -
Yuji Furukawa, Shinji Wada, Yoshihiro Yamada1993 Volume 62 Issue 4 Pages 1127-1130
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSMagnetic and zero-field nuclear magnetic resonance investigations have been made on the La2−xSrxCoO4 system (x=0–1.4), one of the isomorphous compounds of the superconducting cuprates. In the La-rich region (x≤0.5), the antiferromagnetic (AF) ordering persists and the internal magnetic field at 1.4 K remains almost constant (Hint(Co)\simeq200 kOe), though the Néel temperature shows an initial strong decrease with a small amount of Sr substitution. When x increases further (x≥0.6), the AF state suddenly transforms to a ferromagnetic state and the Curie temperature shows a maximum (TC=220 K) at x=0.9. Spontaneous magnetizations at T=4.2 K are, however, non-zero (2.2–1.6 μB) only in the range of x=0.7–0.9, and Hint(Co) strongly decreases from 190 kOe (x=0.6) to below 40 kOe (x=1.1). 59Co spin-lattice relaxation time T1 for x=0.7 and 0.9 follows the relation T1T=const., suggesting it is in a metallic state.View full abstractDownload PDF (548K) -
Yutaka Maniwa, Atsushi Ohi, Kenji Mizoguchi, Kiyoshi Kume, Koichi Kiku ...1993 Volume 62 Issue 4 Pages 1131-1134
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESS13C NMR (nuclear magnetic resonance) in C70 solid was observed between 77 K and 340 K. Clear evidence of a phase transition around 280 K and anisotropic molecular rotation was found in a sublimed C70 solid with purity of more than ∼99%. It was observed that the sample quality significantly affects the C70 molecular dynamics.View full abstractDownload PDF (598K) -
Eisuke Iguchi, Keunjin Lee, Akira Iguchi1993 Volume 62 Issue 4 Pages 1135-1138
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSAnderson’s electron-phonon coupling constants (λ) of a polaron localized at an O− ion and changes in ionic spacing (x) induced by electron-phonon interaction in Ni1−xLixO have been estimated by referring to the experimental results of dielectric measurements and dc-conductivities at low temperatures. Calculations based upon the combination of Anderson’s attractive potential and a shell model yield λ and x of ∼−3.7 eV/Å and ∼−9.8×10−3 Å between O− and Ni2+ in [100] direction, and ∼0.59 eV/Å and 6.9×10−2 Å between O− and O2− in ⟨110⟩, respectively. This calculation provides evidence for the stability of polarons localized at oxygen sites.View full abstractDownload PDF (514K) -
Masaki Maeda, Ikuo Suzuki1993 Volume 62 Issue 4 Pages 1139-1142
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSDielectric properties of mixed crystals of betaine calcium chloride dihydrate and betaine calcium bromide dihydrate (NH3)3NCH2COO·Ca2(1−x)Br2x·2H2O (BCC1−xBxD) were examined down to 4 K and the phase diagram of the mixed crystals was determined.View full abstractDownload PDF (384K) -
Ken Sugawara, Hiroyuki Aoyama, Yasuji Sawada, Kiyoshi Toko1993 Volume 62 Issue 4 Pages 1143-1146
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe mechanism of the oscillatory electric potential of a dioleyl phosphate (DOPH) layer in a single hole sandwiched by two KCl solutions, 100 mM and 5 mM, was investigated using two types of cells for axial and transverse observations. It was discovered that the electrical oscillation was related to a macroscopic behavior of the interfaces between DOPH and KCl solutions caused by a chemically driven surface tension effect.View full abstractDownload PDF (873K) -
Masanobu Kaneko, Takashi Odagaki1993 Volume 62 Issue 4 Pages 1147-1152
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSWe prove that quasiperiodic chains associated with a class of quadratic irrational numbers have an inflation symmetry and can be generated from a regular chain by a hyperinflation. We devise the explicit method to find the hyperinflation symmetry and discuss the properties of such a class of quasiperiodic sequences.View full abstractDownload PDF (678K) -
Narimasa Sasa, Junkichi Satsuma1993 Volume 62 Issue 4 Pages 1153-1158
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA series of exact solutions of the stationary axially symmetric vacuum Einstein equations are discussed based on Hirota’s bilinear method. The solutions are expressed in terms of some determinants and include Neugebauer’s soliton solutions as a particular case.View full abstractDownload PDF (476K) -
Takeshi Iizuka, Miki Wadati1993 Volume 62 Issue 4 Pages 1159-1166
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA two-dimensional anharmonic lattice which has a line discontinuity in the mass distribution is considered. We study scattering of the nonlinear waves due to the mass interface. In the continuum approximation, the incident, reflected and transmitted waves are shown to obey three independent KP equations. By solving the KP equations for sech2-type intial values, we investigate effects of the discontinuous interface on the developement of the incident line soliton. It is shown that the transmitted line soliton breaks up while the reflected soliton does not. The reflection angle is different from the incident angle due to the nonlinearity. These are considered as features of nolinear refraction and reflection phenomena. Our approach is applicable to other two-dimensional nonlinear systems such as shallow water and ion acoustic wave.View full abstractDownload PDF (675K) -
Masakazu Ichiyanagi1993 Volume 62 Issue 4 Pages 1167-1176
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSIt is shown that Mori’s algorithm can be adopted to derive the generalized Langevin equation for nonequilibrium steady states. In this paper, nonequilibrium situations are considered in which there are constant dissipative currents due to the applied constant fields. The two kinds of the fluctuation-dissipation theorem are formed for the simplest nonequilibrium systems.View full abstractDownload PDF (1146K) -
Kunitaka Kondo, Takeshi Chikamatsu, Shin-Hong Kim1993 Volume 62 Issue 4 Pages 1177-1182
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA high PT dilepton event observed in 1.8 TeV \barpp collisions at CDF is analyzed with Dynamical Likelihood Method. A likelihood function for the dilepton decay channel in the t\bart production is given. We illustrate how the method can be applied to eliminate some typical Standard Model processes that could generate spurious events. By assuming that the event comes from the t\bart production, the maximum likelihood mass and the expectation value of mass are evaluated as 124 and 136 GeV/c2, respectively, and a mass range at the 68% confidence level is estimated to be (119,151) GeV/c2, including measurement errors.View full abstractDownload PDF (652K) -
Byong-Soo Min, Yoshitaka Yoshinari, Toshio Watabe, Yasuhito Tanaka, Ch ...1993 Volume 62 Issue 4 Pages 1183-1192
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSPartial ionization cross sections for 4d-electrons in xenon by electron impact have been measured by means of a combination of the electron-energy-loss spectroscopy and the Auger electron spectroscopy in the impact energy region from 70 eV to 4 keV. The cross sections increase with the impact energy rapidly from the threshold and display a sharp maximum, whose value is (17.0±3.5)×10−18 cm2, around 120 eV impact energy, revealing an existence of a resonance. The cross sections arise again from a minimum at about 200 eV and exhibit a broad maximum of (14.5±3.0)×10−18 cm2 around 500 eV. Absolute scale of the cross section is determined using the generalized oscillator strengths for the 4d-ionization, which are measured by the electron-energy-loss spectroscopy. Relative cross sections are measured as a function of the impact energy using an Auger line assigned to the N5O2,3O2,3 (1S0) line. Experimental results are compared with a previous experimental result given by a different procedure and a result of a theoretical calculation.View full abstractDownload PDF (1272K) -
Kenshi Nakamura, Takehiro Takahashi, Tohru Nakano1993 Volume 62 Issue 4 Pages 1193-1201
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWe investigate the temporal development of the statistical properties of two-dimensional incompressible turbulence simulated for a long time. First, we obtain information on the evolving microscopic vortical structure by inspecting the time variation of qth order fractal dimensions of the enstrophy dissipation rate. The conclusion drawn from such an inspection is consistent with a picture given by Kida (J. Phys. Soc. Jpn. 54 (1985) 2840); in the first stage the ∇×ω field grows up in the most advantageous spots of the initial configuration, leading to the very intermittent state, and the energy spectrum is near k−4. Then the turbulence enters the less intermittent stage with the spectrum k−3. Second, we measure the probability density functions (PDF) of the vorticity, its increment over a distance and the enstrophy dissipation rate. The PDFs of the vorticity increment over a small separation and the enstrophy dissipation rate are found to be quite similar to those of the velocity increment and the energy dissipation rate in three dimensions.View full abstractDownload PDF (1135K) -
Osamu Sano1993 Volume 62 Issue 4 Pages 1202-1208
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSA study is made on the diffusion of particles in the thermal convection in a horizontal fluid layer, which is slightly above the critical Rayleigh number. In our experiment, in which almost periodic array of hexagonal cells is generated, a star-shaped spreading of neutrally buoyant particles is observed. Numerical simulation is performed, by taking a spatially periodic regular array of steady laminar hexagonal Rayleigh-Bénard cells as a basic flow, into which particular types of small disturbances are applied. Horizontal distribution of advected particles, particle paths and effective transport coefficient are investigated for various amplitudes, directions and frequencies of the perturbation. The characteristic pattern of impurity is reproduced in laminar hexagonal-cell-like flow with zero mean velocity, with enhanced effective transport coefficient which is proportional to the perturbation amplitude and which becomes maximum at some resonant frequency.View full abstractDownload PDF (956K) -
Isao Katanuma, John A. Tataronis1993 Volume 62 Issue 4 Pages 1209-1220
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe velocity distribution function of electrons created by ionization in a magnetic mirror is determined analytically. It is assumed that electrons trapped in the electrostatic hill of the mirror are controlled principally by externally injected microwave radiation and the axial and radial transport processes. A relationship between the height of the electrostatic potential hill and the density of trapped electrons is derived.View full abstractDownload PDF (1239K) -
Yushi Kato, Kazunori Matsumoto, Shigeyuki Ishii1993 Volume 62 Issue 4 Pages 1221-1232
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSFundamentals of the ECR (electron cyclotron resonance) multiply charged ion source have been experimentally studied with a tandem-type mirror field configuration using low-frequency microwaves (2.45 GHz). By differential pumping, it is possible to sustain discharge in extremely low gas pressures, where multicharged ions can be efficiently produced. A model is proposed to enable investigation of charge-state distribution of argon ions in a plasma and extracted ion currents. The model includes processes of cumulative ionization, recombination, and charge exchange with neutral particles. Ion confinement times depending on the charge state are also included in the consideration of atomic collision and ion diffusion in the direction along the magnetic field (z-axis). The calculations, which take account of charge exchange with neutral particles, are consistent with experimental results. Critical comparison between the data and these calculations suggests that high-temperature electrons are essentially important for multicharged ion production.View full abstractDownload PDF (1477K) -
Shigehiko Nonaka1993 Volume 62 Issue 4 Pages 1233-1244
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSSeveral characteristics of electromagnetic (EM) waves propagating along a bare (or dielectric-coated) plane conductor (or semiconductor) are obtained by solving Maxwell’s equations. The theory was constructed by regarding the metal as an electron plasma. The results were as follows: (I) Dispersion relations and attenuation coefficient for surface wave are obtained in terms of electron relaxation time and electron density in metal, (II) EM propagating modes in the dielectric layer are modified by electron density in metal, (III) Several characteristics of the propagations are also obtained qualitatively, especially on mode conversion between surface wave (SW) and the TM1 mode in the dielectric layer.View full abstractDownload PDF (1517K) -
Hiroyuki Yokoi, Shojiro Takeyama, Noboru Miura, Günther Bauer1993 Volume 62 Issue 4 Pages 1245-1254
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSMagnetic field effects on the structural phase transition in p-Pb1−xGexTe (x=0.01) and n-Pb1−xGexTe (x=0.008) have been investigated by infrared magneto-transmission measurements in the megagauss range using the single-turn coil technique. We have found that the transition temperature Tc increases by 14 K by the application of magnetic fields of 90 T parallel to the [111] direction in p-type samples whose Tc at 0 T is 34 K. Similar dependence has been observed in n-type samples. These results not only provide a support to the previous work by Takaoka and Murase in the low field range below 7 T but also show that the magnetic field effect on the phase transition is even enhanced in the ultra-high magnetic field range without any saturation. We have estimated the critical field of the possible structural phase transition induced by magnetic fields in PbTe.View full abstractDownload PDF (1241K) -
Hiroshi Ajiki, Tsuneya Ando1993 Volume 62 Issue 4 Pages 1255-1266
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe π-electron states of carbon nanotubes (CN’s) in magnetic fields are calculated in the effective-mass theory. A sensitive change of CN from metal to semiconductor depending on its structure is well reproduced. The band gap is inversely proportional to the tube diameter and exhibits a drastic change as a function of magnetic flux passing through the cylinder with period ch⁄e due to the Aharonov-Bohm effect. In a magnetic field perpendicular to the tube axis, the band-gap is reduced strongly and the energy spectra approach those of a graphite sheet.View full abstractDownload PDF (1087K) -
R. J. Nicholas, D. J. Barnes, Noboru Miura, C. T. Foxon, J. J. Harris1993 Volume 62 Issue 4 Pages 1267-1271
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSCyclotron resonance of the 2-Dimensional Electron System in GaAs/Ga0.66Al0.34As heterojunctions has been studied in very high (∼90 T) magnetic fields. The resonance is found to split into two components due to the energy dependence of the electron g-factor. The exact magnitude of the splitting is slightly smaller than observed in bulk GaAs, but is found to be carrier concentration dependent. The intensity of the two different transitions is also found to be carrier concentration dependent, despite the fact that the electron g-factor of the Lowest Landau state is close to zero. This behaviour is interpreted as due to collective electron effects similar to results observed at lower densities and lower temperatures in lower magnetic fields.View full abstractDownload PDF (668K) -
Yoshimi Tsuchiya, Hiroyuki Saitoh1993 Volume 62 Issue 4 Pages 1272-1278
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe electrical conductivity and thermoelectric power have been measured to investigate the semiconductor-metal transition in liquid Ge15Te85. It has been found that the activation energy of the electrical conductivity has a marked peak definitely below the temperature where the specific heat, compressibility and thermal expansion coefficient show sharp peaks. The results have been interpreted as being due to the semiconductor-metal transition associated with dissociation of ionic assembly ‘GeTe4’ in the liquid.View full abstractDownload PDF (785K) -
Ryuta Yagi, Yasuhiro Iye1993 Volume 62 Issue 4 Pages 1279-1285
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSWe have studied energy spectra of a two-dimensional electron system in the presence of a weak magnetic field modulation. It is found that the magnetoresistance shows an oscillatory behavior similar to the so-called Weiss oscillation for the case of an electric potential modulation. The main difference between the two cases is that the phase of the magnetoresistance oscillation is shifted by π⁄2. This results in an inverted peak and valley structure for the magnetic field modulation as compared to the Weiss oscillation. We have also attempted to measure the predicted effect. So far the experimental observation is hindered by the dominant strain-induced Weiss oscillation.View full abstractDownload PDF (838K) -
Yuji Hirao, Masanobu Haraguchi, Masuo Fukui, Gixin Guo, Akira Yoshida1993 Volume 62 Issue 4 Pages 1286-1291
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSA life time of light emitting Au/AlOx/Al tunnel junction which has been widely investigated is usually short at room temperature in the air. We have explored the origin of such a short life time of tunnel junction. It has been found that the degradation of tunnel junction is due to an oxidation of Al film and a destruction of the junction.View full abstractDownload PDF (773K) -
Nobuyuki Momozawa, Yasuo Yamaguchi1993 Volume 62 Issue 4 Pages 1292-1304
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSNeutron diffraction and magnetization measurements have been made on single crystal specimens of hexagonal-ferrite helimagnet (Ba1−xSrx)2Zn2Fe12O22 (x=0.748) in a field applied perpendicular to the c-axis. Two types of intermediate phases, intermediate-I and -II, are successively induced by a field, and their magnetic structures are determined by using the Fourier series expansion method. In each phase, the moments order in fanlike oscillatory structures in which there are large and small spin-bunches perpendicular to the c-axis. The magnetization curve and the turn angle of the helix are discussed from exchange interactions.View full abstractDownload PDF (1369K) -
Yoshiaki Tanaka, Norikiyo Uryû1993 Volume 62 Issue 4 Pages 1305-1316
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSIn the Ising model on a helical lattice with period M (in the limit M→∞ of this lattice, the model corresponds to the two-dimensional Ising model), the exact simultaneous equations to calculate physical quantities are derived. The zero field magnetic susceptibility χ0, and also the specific heat C are obtained numerically for the system of M≤11. Furthermore, in the Ising model with up to the next nearest neighbor interactions on the helical lattice, χ0 and C are calculated for the system of M≤9. The results obtained are an excellent approximation to the exact χ0 and C of the two-dimensional systems.View full abstractDownload PDF (789K) -
Hiroshi Shimahara1993 Volume 62 Issue 4 Pages 1317-1328
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSSpin-fermion model on the CuO2 lattice of the copper oxide high temperature superconductors with inter-CuO2-plane interaction is studied in a perturbation theory with respect to the spin-fermion coupling. Spin waves in a short-range order are phenomenologically assumed, and modification of the spin waves by hole doping which makes the spin correlation functions satisfy the sum rule is taken into account. Antiferromagnetic (AF) phase boundary is obtained on the temperature and hole concentration plane for various strength of the inter-CuO2-plane interaction. AF spin correlation length is also calculated. Relation between the results and experimental results of the copper oxides is discussed.View full abstractDownload PDF (1198K) -
Masayuki Shiga, Koji Fujisawa, Hirofumi Wada1993 Volume 62 Issue 4 Pages 1329-1336
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe roles of geometrical spin frustration in magnetic and thermodynamic properties of YMn2 and Y(Sc)Mn2 are studied. It is shown that the ground state of Y(Sc)Mn2, which exhibits heavy fermion like behavior, may be regarded as a quantum spin liquid realized through the frustration. To confirm this idea, magnetic, thermal and electrical properties of the Y0.95Sc0.05 (Mn1−xAlx)2 pseudobinary system have been studied. The substitution of Al for Mn causes a spin liquid to spin glass transition as a result of partial raise of spin configurational degeneracy.View full abstractDownload PDF (962K) -
Hirofumi Wada, Masahito Nishigori, Masayuki Shiga1993 Volume 62 Issue 4 Pages 1337-1345
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSSpecific heat and high field magnetization were measured for Ce(Fe1−xCox)2, which shows a double magnetic transition in the concentration range of 0.04<x<0.3. The compounds with 0≤x≤0.3 show a specific heat anomaly due to the ferromagnetic to paramagnetic transition at Tc. Magnetic entropy of CeFe2 was evaluated as 2.5 J/K mol, which is much lower than that expected from a localized moment model. Besides anomaly at Tc, another specific heat anomaly due to the antiferromagnetic (AF) to ferromagnetic (F) transition was observed for x=0.1 and 0.2. It is shown that the entropy change associated with the AF-F transition is mainly described by a difference in the electronic specific heat between the F and AF states. The AF-F transition of Ce(Fe1−xCox)2 is discussed from the thermodynamical point of view.View full abstractDownload PDF (1054K) -
Naomichi Hatano, Masuo Suzuki1993 Volume 62 Issue 4 Pages 1346-1353
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSTemperature dependence of the correlation length of the one-dimensional S=2 Heisenberg antiferromagnet is investigated numerically, to compare with those of the S=1⁄2, 1, 3/2 models. The correlation length of the S=2 model is found to be saturated to a value ξ−1\simeq0.012(2) as T→0, which confirms the Haldane conjecture. Combined with the estimate ξ−1\simeq0.16 of the S=1 model by other authors, the present estimate is well explained by ξ−1∼S exp (−πS).View full abstractDownload PDF (857K) -
K. Elankumaran, K. V. S. Rama Rao1993 Volume 62 Issue 4 Pages 1354-1359
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSFerromagnetic resonance (FMR) studies have been carried out on thin films of MnCoxSb system at room temperature (RT). Exchange coupling constant (A) and g-values have been evaluated from the observed spectra. They are found to decrease with increase of Co concentration. The strain anisotropy field changes its sign at a concentration of x=0.18 indicating the spin reorientation occurring in the system. The anisotropy fields calculated from the FMR in powder recorded at X-band and Q-band frequencies also confirm the occurrence of spin reorientation.View full abstractDownload PDF (735K) -
Yutaka Nakai1993 Volume 62 Issue 4 Pages 1360-1364
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSInternal field distributions at Fe and Sn sites in Au(Fe):Sn and Au(CrFe):Sn spin glass systems were evaluated from the Mössbauer spectra in the same method as for Au(Fe) and Au(CrFe) systems. The distributions at both sites agree with each other. Therefore, the previous method of evaluating the internal field distributions as performed for the Au(Fe) spin glass and the related systems is justified.View full abstractDownload PDF (468K) -
Hideaki Goto, Kenzo Baba, Terutaka Goto, Shintaro Nakamura, Akira Tama ...1993 Volume 62 Issue 4 Pages 1365-1371
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe dielectric response of valence fluctuation compound Sm3Se4 has been measured in the frequency range from 20 Hz up to 1 GHz. The resultant response of Sm3Se4 is described by a superposition of two independent dispersions with the Cole-Cole type, which are given by the valence fluctuating state in Sm3Se4 crystal with vacancies. The phase angle θ=90° for the admittance of Sm3Se4 at low temperatures leads the absence of free carrier like in an ideal capacitor. Similar behavior on Sm2Se3 is also presented.View full abstractDownload PDF (767K) -
Tetsuhiko Tomiki, Yoshiiku Ganaha, Tomoyoshi Futemma, Tohru Shikenbaru ...1993 Volume 62 Issue 4 Pages 1372-1387
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe spectra of optical constants of α-Al2O3 single crystals at 297 K and 10 K are presented over the range of photon energies from 6 eV to 120 eV for the electric fields of incident light parallel to optic axis ⟨c⟩ and normal to it. The optical constants include the complex index of refraction, conductivity, complex dielectric constant, loss functions and effective number of electrons per unit cell. The spectra in E\lesssim78 eV are interpreted in terms of the interband transitions from the O 2p and 2s bands to the Al conduction bands and the free electron-like absorption of photons by the O 2p band electrons. The volume energy loss function has a prominent peak at E∼26.4 eV for the plasma oscillation dominantly of the 2p electrons. The spectral features in E\gtrsim78 eV resulting from electronic transitions from the Al L2,3 levels are presented with the L2,3 exciton doublet, e.g., at 78.72 eV and 79.15 eV for ε2⁄⁄.View full abstractDownload PDF (1460K) -
Tetsuhiko Tomiki, Yoshiiku Ganaha, Tohru Shikenbaru, Tomoyoshi Futemma ...1993 Volume 62 Issue 4 Pages 1388-1400
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSThe reflectivity spectrum of Y3Al5O12 (YAG) single crystals at 297 K is presented in the region of 6.734 eV≤E≤116 eV. The spectra of optical constants derived from the reflectivity by the Kramers-Kronig analysis are tentatively interpreted in terms of the energy levels of the constituent atoms of YAG. Plasma resonance peaks are found at 23.38 eV and 36.20 eV in which the valence-band electrons and valence- as well as full-band electrons participate, respectively. The structure of absorption due to excitations of the electrons in the Al3+ L2,3 levels is found in the region of E\gtrsim76 eV. The free electron-like absorption calculated by the Drude formula by use of the line shape parameters of the plasma resonance line is compared with the dielectric constant in the region of E\gtrsim24 eV. The effective optical dielectric constant calculated from the optical constant ε2 is found to be in good agreement at 116 eV with the optical dielectric constant derived from the dispersion formula.View full abstractDownload PDF (1489K) -
Yasuhiro Kondo, Gentaro Ishimori1993 Volume 62 Issue 4 Pages 1401-1406
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSThe two-phonon Raman spectra have been measured for an AgBr single crystal at LHeT, by using a time correlated single photon counting method. The results are compared with the two-phonon density of states based on the extended shell model.View full abstractDownload PDF (732K) -
Kanemitsu Katou, Hiroshi Mamada1993 Volume 62 Issue 4 Pages 1407-1408
Published: April 15, 1993
Released on J-STAGE: June 01, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (248K) -
T. K. Song, S.-M. Lee, S.-I. Kwun1993 Volume 62 Issue 4 Pages 1409-1410
Published: April 15, 1993
Released on J-STAGE: May 29, 2007
JOURNAL RESTRICTED ACCESSDownload PDF (271K)
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