Showing papers in "Journal of the Physical Society of Japan in 1974"
TL;DR: In this paper, the authors investigated the level broadening and transverse conductivity of a two-dimensional electron system under extremely strong fields in the simplest approximation without the difficulty of divergence, in the so-called damping theoretical one.
Abstract: Characteristics of level broadening and transverse conductivity of a two-dimensional electron system under extremely strong fields have been theoretically investigated in the simplest approximation without the difficulty of divergence, i e. in the so-called damping theoretical one. Those of various cases of short- and long-ranged scatterers have been obtained. To see the dependence on the range explicitly, numerical calculation has been performed for the system with scatterers with the Gaussian potential. Especially in case of short-ranged ones the peak value of the transverse conductivity has been shown to be \((N+1/2)e^{2}/\pi^{2}\hbar\) which depends only on the natural constants and the Landau level index. It has been argued from general point of view that this fact is approximately true without reference to kinds of approximations. Such characteristic of the conductivity was confirmed experimentally, but there still remain some problems as to the absolute value of the level width.
545 citations
TL;DR: In this paper, an oscillatory enhancement of the g factor caused by the exchange interaction among electrons is calculated and the degree of spin splitting of each Landau level observed in Schubnikov-de Haas oscillation is shown to be explained by the theory of the level broadening of Landau levels if such enhancement is taken into account.
Abstract: The oscillatory enhancement of the g factor caused by the exchange interaction among electrons is calculated. The degree of the spin splitting of each Landau level observed in Schubnikov-de Haas oscillation is shown to be explained by the theory of the level broadening of Landau levels if such enhancement is taken into account. The g factor is also calculated under tilted magnetic fields, and the theoretical one is in excellent agreement with the experiment by Fang and Stiles, and with the similar one performed recently by Kobayashi and Komatsubara. It is proposed that the valley splitting is enhanced by just the same mechanism and that such enhancement is a possible reason why it is observed experimentally in low-lying Landau levels.
315 citations
TL;DR: In this paper, an analytical analysis of the photoelectron spectra of core electrons and numerical calculations of their overall line shapes are made with the model proposed in our previous paper.
Abstract: Analytic investigations of the photoelectron spectra of core electrons and numerical calculations of their overall line shapes are made with the model proposed in our previous paper. In the final state of the photoemission, an electronic level of the incomplete shell of the excited atom, initially located well above the Fermi energy e F , is assumed to be lowered down to e d due to the core hole left behind. When e d e F , a singular photoemission edge appears at \(\tilde{\varepsilon}_{\text{F}}\), with a weak spectral hump around \(\tilde{\varepsilon}_{d}\). The results are compared qualitatively with experimental data. Finally, some remarks are made on the relationship between the analytic features of the photoelectron and optical absorption spectra.
262 citations
TL;DR: In this paper, the level broadening and transverse conductivity under magnetic fields of arbitrary strength are studied in the simplest approximation free from the difficulty of divergence caused by the singular nature of the system.
Abstract: The level broadening and the transverse conductivity under magnetic fields of arbitrary strength are studied in the simplest approximation free from the difficulty of divergence caused by the singular nature of the system. Scatterers are assumed to be of short-range. The peak value of the conductivity associated with each Landau level decreases slowly with decreasing magnetic field. Assumption of a phenomenological constant relaxation time is not sufficient and the self-consistency is important even under rather weak magnetic fields. The oscillation of the density of states and the conductivity are numerically calculated.
218 citations
TL;DR: In this paper, the phase transition at 130°C is caused by condensation of the M 3 mode at the M point of the cubic Brillouin zone, while the one at 88°C results from condensing of the doubly degenerate R 25 -like mode (Z 9 mode) at the Z point of a tetragonal Brilloupin zone.
Abstract: Structural phase transitions in perovskite-type CsPbBr 3 have been investigated by neutron diffraction method. Phase transitions occur at 88°C and 130°C, which are respectively second and first order. The phase transition at 130°C is caused by condensation of the M 3 mode at the M point of the cubic Brillouin zone, while the one at 88°C results from condensation of the doubly degenerate R 25 -like mode ( Z 9 mode) at the Z point of the tetragonal Brillouin zone. Group theoretical considerations based on these results reveal that the crystal trans-forms from cubic perovskite structure (O h 1 - P m 3 m ) to tetragonal D 4h 5 - P 4/ m b m at 130°C and further to orthorhombic D 2h 16 - P m b n at 88°C. Possible atomic displacements induced at the phase transitions are obtained from the eigenvectors of the condensing modes.
204 citations
TL;DR: In this article, the effects of simultaneous scattering from many scatterers on the level broadening of each Landau level are investigated by assuming short-ranged scatterrs, and the double-site approximation does not give physically reasonable solution of the self-consistency equation which determines the Green's function.
Abstract: Effects of simultaneous scattering from many scatterers on the level broadening of each Landau level are investigated by assuming short-ranged scatterers. The double-site approximation, which is the direct extension of the single-site approximation, does not give physically reasonable solution of the self-consistency equation which determines the Green's function. Such singular behavior is a result of the incorrect analyticity of the self-energy part and is shown to exist in still higher approximations. At high concentrations of scatterers, an approximate infinite summation of the many-site series gives a reasonable density of states, which has low- and high-energy tails and whose width is effectively smaller than that in the lowest approximation.
155 citations
149 citations
TL;DR: In this paper, the inversion asymmetry splitting of the spin degeneracy is investigated for a narrow-gap semiconductor with the zinc-blend structure. But the analysis of the Schubnikov-de Haas measurements of Hg 0.79 Cd 0.21 (e G =68 meV, m 0 * = 0.006 m).
Abstract: Quantized surface states in an inversion later of narrow-gap semiconductor with the zinc-blend structure are investigated theoretically by the effective mass approximation for nearly degenerate bands. When the band gap is small, and the spin-orbit interaction is large, the inversion asymmetry of surface potentioal causes large k -linear term in the two dimensional dispersion relation, which removes the spin degeneracy. Also, the g -factor becomes so large that the reversal of the ordering of the Landau levels is expected. The theory is applied to the analysis of the Schubnikov-de Haas measurements of Hg 0.79 Cd 0.21 ( e G =68 meV, m 0 * =0.006 m). The inversion asymmetry splitting of the spin degeneracy is as large as several meV, and the inversion in the order of Landau levels is expected to be observed. The surface potentioal of the sample is expressed in the parametrized form, and values of the parameters are estimated by using the experimental data.
139 citations
TL;DR: In this article, a new type of surface mode of the electromagnetic wave is predicted in the case when charge carriers are located at the boundary of dielectric media, and its characteristic feature is discussed.
Abstract: A new type of surface mode of the electromagnetic wave is predicted in the case when charge carriers are located at the boundary of dielectric media. The dispersion relation of the mode is derived and its characteristic feature is discussed. Effect of the surface carrier is represented in terms of characteristic frequency \(\varOmega_{s}\) (=4π N s e 2 / m * c ; N s is density of the surface carrier). The dispersion takes the linear form in the low frequency region (\(\omega{\ll}\varOmega_{s}\)), while it has the square root form (\(\omega{\propto}\sqrt{k}\)) in the high frequency limit (\(\omega{\gg}\varOmega_{s}\)). In contrast to the case to the absence of surface carriers the present mode exists in the frequency region where at least one of the dielectric functions of the adjacent media takes positive value. As a numerical example the dispersion relation is calculated and illustrated for clean surface of p -type InAs.
134 citations
TL;DR: In this article, the level broadening and transport properties of a two-dimensional system under extremely strong magnetic fields are investigated in the single-site approximation (SSA) method.
Abstract: The level broadening and transport properties of a two-dimensional system under extremely strong magnetic fields are investigated in the single-site approximation (SSA). At high concentrations of scatterers, the SSA approaches the simple damping theoretical approximation. At low concentrations, many impurity bands associated with each bound state of an isolated scatterer appear, and the nonexistence of continuous states in this system causes a singular level with zero width in case of scatterers with a δ-potential. The peak value of the conductivity of the impurity band with the angular momentum m is given by \(2\pi l^{2}N_{i}(N+m+1/2)e^{2}/\pi^{2}\hbar\), where N is the Landau quantum number and N i is the concentration of scatterers. The density of states and the conductivity are calculated explicitly for a model system which contains scatterers with the Gaussian potential.
130 citations
TL;DR: In this article, the critical dynamical behavior of the pseudospin-phonon coupled system has been investigated in connection with the structural phase transition of molecular crystals based on Onsager's equation of motion.
Abstract: The critical dynamical behavior of the pseudospin-phonon coupled system has been investigated in connection with the structural phase transition of molecular crystals. Based on Onsager's equation of motion, explicit expressions for three correlation functions, spin-spin correlation, phonon-phonon correlation and spin-phonon correlation, are obtained. It has been shown that the characteristic of the spectra of these correlation functions shows wide variation depending on the values of two parameters: The ratio of the relaxation rate of reorientational motion of an isolated spin and the frequency of the phonon, and the ratio of the interaction parameter of direct spin-spin coupling and that of spin-phonon coupling. Especially, in `fast relaxation case', the spectrum of phonon-phonon correlation shows critical softening, whereas, in `show relaxation case' the spectrum gives `triple peak' structure and only the central (relaxational) mode shows critical slowing down leaving phonon side peaks unchanged.
TL;DR: In this paper, the elastic constants of disordered Fe 72 Pt 28 single crystal have been measured as a function of temperature and the magnetic contribution to the shear modes can be described by the relations - C'm = K 1 (M/M 0 ) 2 and - C m = k 2 (M / M 0 ), where K 1 and K 2 are magnetoelastic coupling coefficients.
Abstract: The elastic constants of a disordered Fe 72 Pt 28 single crystal have been measured as a function of temperature. All elastic constants behave highly anomalously below T c due to the Invar properties of this alloy. The magnetic contribution to the shear modes C '=( C 11 - C 12 )/2 and C = C 44 can be described by the relations - C ' m = K 1 ( M / M 0 ) 2 and - C m = K 2 ( M / M 0 ) 2 where K 1 and K 2 are magnetoelastic coupling coefficients. Using these relations the elastic constants at 0K are C '=0.3×10 10 N / m 2 and C =7.5×10 10 N / m 2 giving rise to an elastic anisotropy of A = C / C '=25. The elastic constant C L behaves differently. C L goes through a minimum at 50°C and a magnetically induced reduction is present up to 200° above T c . This is ascribed to a coupling between the longitudinal sound wave and spin fluctuations.
TL;DR: In this article, the wave propagation in an infinite one-dimensional anharmonic lattice is studied under the influence of an an-harmonic potential and a weak dislocation potential and it is found that the equation for the nonlinear wave propagation has N -kink solution.
Abstract: The wave propagation in an infinite one-dimensional anharmonic lattice is studied under the influence of an anharmonic potential and a weak dislocation potential. It is found that the equation for the nonlinear wave propagation has N -kink solution. The properties of one and two kink solutions are discussed in detail. It is also found that there exists the critical eigenvalue due to the competition between the above two kinds of potentials . A few conservation laws are obtained.
TL;DR: In this paper, the energy spectrum of exciton polaron is studied with the dynamical CPA (coherent potential approximation), which is introduced for inelastic scattering by Einstein phonons at every lattice site.
Abstract: Energy spectrum of exciton polaron is studied with the dynamical CPA (coherent potential approximation), which is introduced for inelastic scattering by Einstein phonons at every lattice site. The coherent potential at energy E is determined by the potentials at energies apart from E by integral times the phonon energy. We determine applicability ranges of the concepts used in the limiting cases; (I) the nearly free exciton for weak coupling, (II) multiple bands of the vibronic excitons for small excitation transfer, and (III) the self-trapped exciton for strong coupling. An ambiguous boundary separating (II) and (III) lies about S ≃6, with S representing the ratio of the energy gain of exciton localization to the phonon energy. The change with increasing excitation transfer for a fixed S is characterized by the sharp crossing of (III) with (I) for \(S{\gtrsim}6\), while by the gradual merging of (II) into (I) for \(S{\lesssim}6\).
Journal Article•
TL;DR: In this article, the authors studied the magnetic properties of disordered γ-phase Mn 1-x Ir x (0.05 1) and showed that the anomalous rise of T N is not mainly attributed to atomic order nor to the enhancement of exchange interaction due to lattice expansion, but that the perturbation of band structure due to alloying leads to stronger magnetic interaction.
Abstract: Crystallographic and magnetic properties were studied in the disordered γ-phase Mn 1- x Ir x (0.05 1 occurs at a temperature below their Neel temperature, T N . The tetragonal distortion temperature, T d in the antiferromagnetic ordered state decreases rapidly with increasing Ir and the alloys with x >0.15 remain cubic down to low temperatures. On the other hand, T N increases with alloying Ir at a rate of about 9 K/at%Ir up to 730 K at x =0.25 and it is extrapolated to 500±20 K for fcc Mn. It was concluded that the anomalous rise of T N is not mainly attributed to atomic order nor to the enhancement of exchange interaction due to lattice expansion, but that the perturbation of band structure due to alloying leads to stronger magnetic interaction. A Cu 3 Au type atomic ordering in the vicinity of x =0.25 was found to raise the T N by about 200 K. The origin of tetragonal distortion is discussed.
TL;DR: In this article, three wave mode coupling effects on ion acoustic waves are examined by applying the Fourier transformation method of separation of the nonlinear slow processes for a two component plasma described by the Vlasov equation.
Abstract: Three wave mode coupling effects on ion acoustic waves are examined by applying the Fourier transformation method of separation of the nonlinear slow processes for a two component plasma described by the Vlasov equation. Contribution of the three mode coupling terms gives rise to a modified Korteweg de Vries equation with a nonlinear term of the form of { B φ+( C /2)φ 2 }φ x , where B and C are constants determined by the unperturbed state of plasmas. It is found that velocity of a stationary solitary wave depends sensitively on the electronion temperature ratio, and that the equation obtained here enables us to account for the amplitude dependence of the solitary wave velocity observed by Ikezi, Baker and Taylor.
TL;DR: In this article, the authors present a method by which they can describe the many exciton system transparently by making the best use of the boson like character of Wannier excitons.
Abstract: We present the method by which we can describe the many exciton system transparently by making the best use of the boson like character of Wannier excitons. Basing upon this method, the total energy of this system and the number of bose-condensed excitons are calculated as a function of the total concentration of excitons, and we show how the boson like character of Wannier excitons is reflected on the emission spectrum from this system and on the absorption spectrum in the presence of these excitons at finite density.
TL;DR: In this article, an extra absorption band with two peaks is observed at the low energy region of the absorption edge for Fe-doped CuAlS 2 and CuGaS 2, respectively.
Abstract: Optical absorptions have been measured in chalcopyrite, CuFeS 2 , and Fe-doped CuAlS 2 and CuGaS 2 An extra absorption band with two peaks is observed at the low energy region of the absorption edge for Fe-doped CuAlS 2 and CuGaS 2 Energy positions of two absorption peaks are 13 eV and 20 eV for CuAlS 2 and 12 eV and 19 eV for CuGaS 2 , respectively The intensity of this absorption band increases with the increase of doped Fe ions and grows into the absorption edge of CuFeS 2 Its oscillator strength comes up to 7·10 -2 In chalcopyrite photoconductivity is observed and its maximum is just at the same energy region of the absorption edge By comparing our results with those of absorption measurements for Cu- or Fe-doped ZnS it is concluded that this absorption band originates from the charge transfer transitions relating to 3d electron of Fe ions and the absorption edge of CuFeS 2 rises from the band-to-band transition corresponding to this charge transfer transition
TL;DR: In this paper, the existence of the satellite accompanying the 4d 5/2 and 4d 3/2 components is shown by an analysis of the spectra obtained by deconvolution of the raw data of La-halides.
Abstract: X-ray photoemission spectra have been measured of the 4d and 3d shells of La 3+ and Ce 3+ in La- and Ce-halides. The results, particularly in the case of the spectra of the 4d level, show a marked dependence of spectral profile of halogen. The existence of the satellite accompanying the 4d 5/2 and 4d 3/2 components is shown by an analysis of the spectra obtained by deconvolution of the raw data of La-halides. The halogen dependence of the spectra is ascribed to the simultaneous charge transfer transition from the valence level of ligand to the unoccupied 4f level of the metal ion as being the orgin of the satellite.
TL;DR: In this article, the reflection spectra of KDP and ADP were studied in the vacuum ultraviolet region up to 35 eV and the peak energies in the reflection spectrum with the energy levels and taking the polarization characteristics into consideration, tentative assignment was given to the bands observed.
Abstract: The reflection spectra of KDP and ADP are studied in the vacuum ultraviolet region up to 35 eV Polarized light is used in the study of low energy part below 13 eV Some peaks in the spectra are found to show remarkable dependence on the polarization of the incident light The energy levels of PO 4 3- , H 2 PO 4 - and H 4 PO 4 + are calculated by the extended Huckel method By comparing the peak energies in the reflection spectra with the energy levels and taking the polarization characteristics into consideration, tentative assignment is given to the bands observed
TL;DR: In this paper, the flow around a flexible plate performing a swimming motion was investigated using hot-wire anemometers, pressure transistors and flow visualization techniques, and it was found that the swimming motion accelerates the flow near the surface in the wave direction, reduces the boundary layer thickness, and suppresses the turbulent fluctuation.
Abstract: The flow around a flexible plate performing a swimming motion was investigated using hot-wire anemometers, pressure transistors and flow visualization techniques It was found that the swimming motion accelerates the flow near the surface in the wave direction, reduces the boundary layer thickness, and suppresses the turbulent fluctuation
Abstract: Weakly nonlinear capillary waves on a liquid column of circular cross-section are investigated on the basis of the derivative expansion method It is found that the complex amplitude of a quasi-monochro-matic travelling wave can be described by a nonlinear Schrodinger equation in a frame of reference moving with the group velocity The known property of this equation reveals that wave trains of constant amplitude are modulationally unstable, which suggests a new possibility of the break-up of column On the other hand, the complex amplitude of a quasi-monochromatic standing wave near the cut-off is governed by another type of nonlinear Schrodinger equation in which the role of the time and that of the space are interchanged This equation makes it possible to estimate the nonlinear effect on the cut-off wave-number
TL;DR: In this paper, it was shown that the equations of motion lead to the inelastic scattering of thermal phonons, resulting in transfer of their momentum to the dislocation, and the frictional force by this mechanism has the T 3 -dependence at low temperatures.
Abstract: The frictional force acting on the dislocation is calculated for the fluttering mechanism based on the continuum approximation. It is shown that the equations of motion lead to the inelastic scattering of thermal phonons, resulting in transfer of their momentum to the dislocation. The frictional force by this mechanism has the T 3 -dependence at low temperatures. If we use the Debye cut-off, the magnitude is about 1.6×10 -4 dyne·sec/cm 2 for Cu at room temperature.
TL;DR: In this article, a theory of nematic ordering in liquid crystals was developed and the method of symmetry-breaking potential and a first-order cluster expansion technique for the partition function were employed.
Abstract: A theory of nematic ordering in liquid crystals has been developed. The method of symmetry-breaking potential and a first-order cluster expansion technique for the partition function are employed. The obtained results agree with those of the Onsager-Isihara (for hard rods) and of the Meiar-Saupe (for dispersion forces) theories in respective limiting cases. The nematic order parameter is calculated as a function of temperature and density of liquids; the calculated values agree very well with the experimental ones on nematic para-azoxyanisole for the pressure range from 1 to 640 ber. The nematic-isotropic transition temperature T c is calculated as a function of the density and shape of molecules (length, breadth and their ratio). The theory provides good explanations, at least qualitatively, of behavior of T c for various homologous series of nematic liquid crystals.
TL;DR: A general relation exists between the relative magnitude of the power spectra J ( m ) (ω) that appear in the expressions of nuclear spin relaxation times T 1, T 2 and T 1ρ of powdered specimen, i.e. the relation holds exactly in the weak collision case irrespective of the modes of motion responsible for the relaxation as discussed by the authors.
Abstract: A general relation exists between the relative magnitude of the power spectra J ( m ) (ω) that appear in the expressions of nuclear spin relaxation times T 1 , T 2 and T 1ρ of powdered specimen, i.e. J (0) (ω): J (1) (ω): J (2) (ω)=6:1:4. the relation holds exactly in the weak collision case irrespective of the modes of motion responsible for the relaxation. The proof is based on the symmetry properties of the spherical harmonics of rank two and therefore applicable not only to dipole-dipole but also to quadrupole coupling interaction and other problems. The reduction factor of the second moment of the nuclear magnetic resonance that results from a type of molecular motion also bears a simple general relation to the minimum value of T 1 due to the motion.
TL;DR: In this paper, the electrical resistivities have been measured in temperature range from 4.2 K to 300 K on both deformed and quenched aluminum, and the deviations from Matthiessen's rule have been observed in both the resistivity of dislocations and of the faulted loops formed by quench-in vacancies.
Abstract: The electrical resistivities have been measured in temperature range from 4.2 K to 300 K on both deformed and quenched aluminum, and the deviations from Matthiessen's rule have been observed in both the resistivity of dislocations and of the faulted loops formed by quenched-in vacancies. The deviations show comparatively similar behavior as the whole, but in detail show somewhat different profile. The results were compared with data published by the other investigators. It is concluded that the origin of the deviation for the dislocation resistivity comes from the anisotropy in scattering mechanism. Furthermore the specific electrical resistivity of dislocation and stacking fault in aluminum were estimated as 1.2×10 -19 ohm-cm 3 and 3.7×10 -13 ohm-cm 2 , respectively.
TL;DR: In this article, the down-and up-spin Green functions were obtained in the weak s − d interaction limit with the results of the molecular field approximation and in the strong interaction limit, respectively.
Abstract: Electronic structure in magnetic semiconductors is investigated on the basis of the s - d exchange model. The exchange scattering of an electron by localized spins is treated in the coherent potential approximation. Coupled equations for the down- and up- spin Green functions are obtained. These equations agree in the weak s - d interaction limit with the results of the molecular field approximation and in the strong interaction limit with those obtained previously by the present author. The density of states for down- and up- spins is calculated in the paramagnetic and completely ferromagnetic states for various values of interaction strength, by assuming a semi-elliptic form for unperturbed density of states.