bluuebunny/crossref_metadata_2025 huggingface dataset:
A Scaling Approximation of Quasi-Particle Interaction in Helium II
Authors: Chow W. K. , Fung P. C. W. , Wong K. W.
Published: March 2014

The thermodynamic variables are expressed in terms of the elementary excitation spectrum obtained from the combined correlation-basis-function and canonical transformation method. A scaling factor accounting for the quasi-particle interaction is logically introduced. By adjusting its value we obtain good results to the thermo-dynamic variables for superfluid helium 4.
Magnetically Ordered Structures of Nuclear Spins in fcc Metals
Authors: Oja A. S. , Viertiö H. E.
Published: March 2014

In order to find how the extensive degeneracy is lifted in the mean field ground state of nuclear spins in fcc metals, various fluctuation effects have been investigated. In exchange dominated systems like silver and gold, quantum fluctuations result in a simple 1-k̄ structure, while a strong dipolar interaction is predicted to stabilize a 2-k̄ state in copper. In natural isotopic mixtures of copper and silver there are two magnetic isotopes. This randomness favors a 3-k̄ structure. The effects of thermal fluctuations are also discussed.
Theory of the Coherent Heavy Fermion State: Universal Behavior, Pressure Dependence and Neutron Scattering Cross Section
Authors: Auerbach Assa , Levin K.
Published: March 2014

We discuss a solution of the Anderson lattice Hamiltonian within a 1/N expansion framework which provides a well controlled microscopically based description of the coherent heavy fermion state and associated Landau parameters. This theory has been previously used to explain systematic scaling with γ (the linear coefficient of the specific heat) of the T2 contribution to the resistivity and T3lnT term in the specific heat. Here it is also extended to discuss recent neutron experiments. Antiferromagnetic peaks in the neutron cross section which correspond to zone boundary wave vectors and frequencies of the order of TK arise naturally as a consequence of transitions across the hybridization gap. Finite frequency structure at low wave vectors derives from f-spin non conserving processes which occur at the 1/N level when a realistic c-f hybridization to a local crystal field doublet is included in the Anderson lattice.
Interacting Fermions: Correlation Functions Obtained with the Gutzwiller Wave Function
Authors: Gebhard Florian , Vollhardt Dieter
Published: March 2014

A recently developed analytic approach is used to calculate correlation functions for interacting spin-1/2 fermions on a lattice in terms of the Gutzwiller wave function. In one dimension the evaluations are performed analytically and without any approximation. Whenever possible comparison with exact results (Hubbard-model, spinless fermions) is made.
Hydrodynamic Fluctuations in Heavy Fermion Systems
Authors: Becker K. W. , Fulde P.
Published: March 2014

A theory of hydrodynamic fluctuations is presented. We find that the displacement-displacement correlation function for the lattice contains an overdamped hydrodynamic mode which is due to electro density fluctuations. Since the Landau-Placzek ratio is 5–6 orders of magnitude larger than in ordinary metals the electron-diffusion mode should be experimentally observable. In fact it seems that they have been observed already. We also discuss the density mode at small wave vectors outside the hydrodynamic regime. The electron-diffusion mode converts into a propagating mode which has features of an acoustic plasmon or zero sound. In addition we find high energy plasmons and a low energy optical plasmon which is expected when more than one heavy quasiparticle band intersects the Fermi level.
Specific Heat due to Spin Fluctuations in Nearly Ferromagnetic and Heavy Electron Metals
Authors: Konno Rikio , Moriya Tôru
Published: March 2014

The specific heat due to extended (long wavelength) paramagnons is expressed by using four parameters associated with the band structure and the exchange enhancement factor. The expansion form
γT+δT3ln
T+βT3 of this expression is shown to be valid only at extremely low temperatures outside the range of existing measurements, while the full expression seems to explain the results of measurements. In the localized paramagnon limit, as may be the case in certain heavy electron systems, We find a T3 ln
T-lime behavior in a certain temperature range around a characteristic temperature.
Thermoelectric Power of Ce Impurity in Cubic Crystalline Field at Low Temperatures
Authors: Kawakami Norio , Okiji Ayao
Published: March 2014

The low-temperature thermoelectric power of the Ce impurity system is investigated precisely by means of the Bethe-Ansatz solution of the Anderson model. The crystal-field effect on the giant thermoelectric power is discussed for the cubic field with the results obtained for the specific-heat enhancement factor and the renormalized f-level position.
Study of Elementary Excitations in He II by Raman Scattering
Authors: Ohbayashi Kohji , Akagi Toshiya , Ogita Norio , Watabe Mitsuo , Udagawa Masayuki
Published: March 2014

Raman spectra of liquid 4He have been measured in the temperature region from 0.65 K to 4.2 K under pressure from svp to 20 kg/cm2. Many fine structures have been found as well as the strong two-roton peak. A new proposal is made to interpret the fine structures to be associated with multi-phonon processes of not only two but also more than two elementary excitations. Detailed measurements of the pressure dependence of the two-roton peak have been done. From the pressure dependence of the shift of the two-roton peak, we can claim that the two-roton interaction change from attractive at low pressure to repulsive at higher pressure.
Acoustic de Haas-van Alphen Effect of CeB6 and LaB6
Authors: Suzuki T. , Goto T. , Sakatsume S. , Tamaki A. , Kunii S. , Kasuya T. , Fujimura T.
Published: March 2014

All of the main orbits of LaB6 have been observed successfully by the ultrasonic measurement of dHvA oscillations of elastic constants without field modulation technique, where the high resolution important. Adopting the ultrasonic technique in a dilution refrigerator, the acoustic dHvA oscillation of CeB6 is obtained for the heavy fermion with effective cyclotron mass ∼7.2m0 of the extremal orbit 0.012 A-2(1.26MG)
Concentration Dependence of Specific Heat of CexLa1-xCu6
Authors: Satoh Kazuhiko , Kato Masatsume , Maeno Yoshiteru , Fujita Toshizo , Ōnuki Yoshichika , Komatsubara Takemi
Published: March 2014

Specific heat of a dense-Kondo system CexLa1-xCu6 has been measured systematically down to 0.1 K. With decreasing the Ce concentration, the specfic heat per molar Ce increases and the Kondo temperature is found to decrease. Also the results are reasonably compared with theories for the dilute-Kondo system.
Preparation and Electrical Transport Properties of Ce1-xLaxCu6-Thin Films
Authors: Adrian G. , Adrian H. , Möhle W.
Published: March 2014

We report the preparation of Ce1-xLaxCu6 thin films and measurements of resisitivity ρ(T), Hall-effect RH(T), and magnetoresistivity Δρ(B,T). For CeCu6-films structures in ρ(T) and a T2-behavior below 0.18K, characteristic for Heavy Fermion systems, are observed. The formation and coherence of heavy quasiparticles is also reflected in strong temperature dependences of RH(T) and Δρ(B,T). These Heavy Fermion properties disappear at a La-concentration of x = 0.25. Increasing x further leads to a dilute Kondo impurity behavior.
Low Energy Optical Excitations of CeBi
Authors: Kwon Y. S. , Kitazawa H. , Sato N. , Abe H. , Nanba T. , Ikezawa M. , Takegahara K. , Sakai O. , Suzuki T. , Kasuya T.
Published: March 2014

The optical reflectivity was measured in the single crystal of CeBi at 300K and 10K. The absorption due to the Kondo peak was observed around 6meV at low temperature and that of the f-d transition was observed in the infrared region at both temperature. Virtual excitons with a certain space
extention are considered.
Specific Heat of a New Dense-Kondo Compound CePdIn
Authors: Maeno Y. , Takahashi M. , Fujita T. , Uwatoko Y. , Fujii H. , Okamoto T.
Published: March 2014

The specific heat of a newly-found dense-Kondo compound, CePdIn, has been measured between 1.8 and 80 K. The magnetic contribution to the specific heat, Cm = C(CePdIn)-C(LaPdIn), is explained by a simple sum of the Schottky specific heat between the ground and the first excited doublets ( Δ=120 K) and the Kondo specific heat (TK≃4 K). The ratio Cm/T increases rapidly below about 15 K and reaches 0.33 J/K2mol already at 4 K, which is more than twice the magnetic ordering temperature TN=1.8 K.
Magnetic Properties of the Pseudo-Ternary System CeRh2Si2-xGex–A Kondo-Necklace
Authors: Godart C. , Gupta L. C. , Tomy C. V. , Vijayaraghavan R. , Thompson J. D.
Published: March 2014

CeRh2Si2 undergoes an antiferromagnetic phase transition at 37K which is unusually high for in Ce-based system. It is known that at moderate pressures, magnetic ordering in CeRh2Si2 is completely suppressed. Substituting Ge for Si, which is equivalent to applying a negative pressure to the system, gives rise to a very interesting effect: TN of the pseudo-ternary system CeRh2Si2-x Gex first increases (TN=38.5K for x = 0.125) and then decreases as x increases. The slope dTN(x)dx is largest at x = 1. X-ray measurements confirm that the system crystallizes in ThCr2Si2-structure for the entire range of x (0 x 2) and there is no anomaly in lattice constants. Magnetic susceptibility measurements carried out in the temperature interval 4.2K T 300K show that cerium atoms are in trivalent valence state. We argue that these observations can be understood on the basis of Doniach's Kondo-necklace model.
Nonlinear Magnetotransport of the Magnetic Field-Induced SDW State in the Organic Superconductor
Authors: Osada Toshihito , Miura Noboru , Oguro Isamu , Saito Gunji
Published: March 2014

We have observed a nonlinear transport behavior in the magnetic field-induced spin-density-wave (SDW) state in (TMTSF)2ClO4 at low temperatures. The nonlinearity appears only in the diagonal conductivity with a very small threshold electric field. This observation is indicative of a possibility that the sliding motion of the SDW is responsible for this nonlinearity. The electric field dependence of the small period oscillations similar to the Shubnikov-de Haas effect suggests that this oscillatory phenomenon relates to some kind of tunneling mechanism.
Origin of Small-Period Oscillatory Magnetoresistance in Bechgaard Salts
Authors: Yamaji Kunihiko
Published: March 2014

On the basis of an anisotropic two-dimensional band modeling the Bechgaard salts, we study into the effect of the title in terms of Umklapp process matrix elements of the SDW periodic potential, which are calculated by using one-electron eigen wave functions obtained in the normal state in the magnetic field H with due regard to the dimerization along the conducting axis. The Umklapp matrix elements produce small gaps of order 0.03 meV in addition to the bigger Landau band gaps in the energy spectrum. These gaps pulsate reaching zero with a period close to the observed small period in 1/H. The phenomenon of the title is ascribed to the Zener tunneling of thermal current carriers through these pulsating small gaps.
Fermi Surface Modifications and Magnetic Breakdown Connected to Charge-Density Waves in NbSe3
Authors: Coleman Robert V. , Everson M. P. , Falicov L. M. , Lu Hao-An , Johnson A.
Published: March 2014

The magnetoquantum oscillations in NbSe3 show frequency shifts and beat structures due to interaction with the pinned charge-density-wave (CDW) configuration. Measurements in magnetic fields up to 220 kG indicate that local deformations of the pinned CDW cause extremal area changes in small lens-shaped sections of normal Fermi surface (FS). Calculations of magnetic breakdown (MB) to the open nested sections of FS with a distribution of areas at the MB junctions can explain the data.
Study of 2D Electron Gas Properties in Acceptor Graphite Intercalated Compounds
Authors: Joss W. , Ruitenbeek J. M. Van , Vagner I. , Rachdi M. , Roth S.
Published: March 2014

The oscillatory magnetization of stage 1 and 2 AsF5 intercalated graphite compounds was measured with the de Haas-van Alphen torque method in fields up to 22 T. From the angular dependence of the de Haas-van Alphen frequency and the cyclotron effective mass we conclude that the Fermi surface is ideally cylindrical. The Landau levels are found to be well separated compared with the broadening due to imperfections. Despite this fact the wave form of the oscillations is perfect sinusoidal in contrast to the standard theory.
Electronic Specific Heat of Gamma Phase Copper-Cadmium Alloys
Authors: Collocott Stephen J. , Rayne John A.
Published: March 2014

The electronic specific heat of the γ-phase in the binary coppei-cadmium system has been measured as a function of composition from 0.5K to 5K. A very rapid decrease with electron/atom ratio is observed in the corresponding density-of-states at the Fermi level. The behavior supports the view that this phase is a Hume-Rothery electron compound and the electronic structure is determined by contact between the Fermi surface and the relevant Jones zone for the γ-brass structure. Results for both the electronic specific heat coefficient and the Debye temperature as a function of electron concentration are compared with those for the γ-phase of the copper-zinc and the γ2 phase of the coppei-aluminum binary alloy systems.
Scattering of Electrons by Kinks on the Dislocation Line in a Metal
Authors: Mukhin Serge
Published: March 2014

The interaction between conductivity electrons in a metal and the dislocations containing kinks in the Peierls potential relief is investigated theoretically. At low temperatures and sufficiently low density of other defects inelastic scattering of electrons by the kinks leads to a quadratic temperature dependence of the thermal conductivity of the sample along the favored direction of the dislocation axes,In a plane perpendicular to the dislocation axes,elastic scattering of electrons by the dislocation cores is predominant.
Temperature and Magnetic Field Dependence of the Tunnel Resistance of Pure and Doped Al–O–Al Junctions
Authors: Spahn E. , Keck K. , Wiesner H.
Published: March 2014

At temperatures between 1.9 K and 1.2 K (Tc of Al) we found that Al-O-Al tunnel junctions (TJ) show an extremely steep resistance Increase accompanied with a negative magnetoresistance (MR∼ln B). Doping the TJ with Au, which already has a strong spin-orbit coupling, we observe a positive MR at low temperatures. The influence of magnetic impurities, e.g. Ni, leads to a widening of the MR curves of undoped TJ. Near Tc superconducting fluctuations contribute to the inelastic scattering processes. These results are corresponding to the behaviour of weak localization in disordered two-dimensional metallic films.
Geometrical Resonance in Sb Doped Si near the Metal-Nonmetal Transition
Authors: Ishiguro Hideto , Ochiai Yuichi , Yoshizaki Ryozo , Suzuki Tetsuro
Published: March 2014

In ultrasonic wave resonance of Sb doped Si ( 1×108 cm-3 ) we have observed several peaks in the temperature dependence of the linewidth of low frequency resonance signals from 10 to 80 K. There exists a strong magnetic field dependence of the linewidth at the same resonance signals. It is found that these peaks come from a relaxation process in the localized electronic state having a energy gap. On the other hand, at metallic sample ( 1×1019 cm-3 ) we can observe no relaxation process. Comparing our result with other studies, we consider that the relaxation process can be explained by the valley orbit splittings of the ground state of Sb donor in Si.
Berry's Phase and Localization for Phonons in Helically Wound Rods
Authors: Igarashi Jun-ichi
Published: March 2014

A manifestation of Berry's topological phase is considered for transverse acoustic phonons in helically wound rods. The transmitted intensities are calculated for rods with random refractive index, and the interference patterns are discussed in connection with the Anderson localization.
Numerical Study of Universal Conductance Fluctuations
Authors: Giordano N.
Published: March 2014

We have used numerical techniques to study conductance fluctuations in disordered one and two dimensional tight binding models. We have focussed on the conductance fluctuations produced by the movement of a single impurity, and study how the magnitude of these fluctuations varies as the length of the system is increased. Our results indicate that the fluctuations vary much more weakly with sample length than has been predicted from analytic calculations.
Measurement of the Specific Heat of the 2-D Electron Crystal
Authors: Glattli C. D. , Andrei E. Y. , Williams F. I. B.
Published: March 2014

We measured the specific heat of a 2-D electron crystal above liquid Helium. For electronic temperatures Te≤0.8Tm , where Tm is the melting temperature, we found that the specific heat fits well a Debye model with renormalized elastic constants. At melting we observed no jump in the specific heat, indicating that the transition is of continuous order, in accord with the Kosterlitz-Thouless model of melting via unbinding of dislocations.
Nonlocal Plasmon Spectrum of a Superlattice in a Quantizing Magnetic Field: Bernstein-Mode Branch
Authors: Gumbs Godfrey
Published: March 2014

The dispersion relation of the nonlocal plasmon spectrum of a layered two-dimensional electron gas (2DEG) at low temperature in a quantizing magnetic field perpendicular to the layers is examined. Magnetoplasmons of this system have been studied by others, but they have considered only the lowest band in the plasmon spectrum. The excitation spectrum of a 2DEG has been found to have branches analogous to “Bernstein” modes near multiples of the cyclotron frequency for n≥2. For a periodic array of 2DEG layers, the Bernstein modes interact to form bands. Explicit results are presented for the degenerate case in the high-field quantum limit, when all electrons are in the lowest Landau eigenstate.
Resonant Magnetotunneling in AlGaAs/GaAs Triple Barrier Diodes
Authors: Bando Hiroshi , Nakagawa Tadashi , Tokumoto Hiroshi , Ohta Kimihiro , Kajimura Koji
Published: March 2014

Resonant magnetotunneling in a triple barrier diode, where two quantum wells are formed by three barriers, is studied by applying magnetic fields both perpendicular and parallel to the interfaces. Under the perpendicular magnetic field, an oscillatory structure is found in the current-voltage characteristics (I-V's) in addition to the large peaks which have been found without magnetic field. The period of the oscillation is proportional to the magnetic field. The structure is attributed to inelastic tunnelings with an LO-phonon emission and subsequent change in the Landau quantum number. Under the parallel magnetic field, strong broadening of the large peaks towards a larger
bias is found. A model for the broadening is proposed.
Thermal Convection in 3He–4He Mixtures near the Tricritical Point
Authors: Ardron M. R. , Lucas P. G. J. , Tucas A.
Published: March 2014

Exploratory experiments are described that investigate 3He–4He mixtures near the tricritical point as convection systems. Measurements of the temperature difference between the horizontal boundaries of a convection cell heated from above exhibit features attributable to phase separation and the bulk superfluid transition but show no feature consistent with the onset of stationary convection. The presence of convection is inferred from enhanced thermal conduction and the existence of a time-dependent state showing similarities to Busse's oscillatory instability. The effect of superfluid film flow was very noticeable and measurements of the film superfluid transition temperature are presented for four concentrations of 3He in 4He.
Spin Glass-like Behaviors in a Frustrated Antiferromagnet MnCl2-GIC
Authors: Matsuura Motohiro , Karaki Yoshitomo , Yonezawa Takeshi , Suzuki Masatsugu
Published: March 2014

Magnetic ordering of a triangular antiferromagnet MnCl2-graphite intercalation compound is investigated by thermal and magnetic measurements. All the experimental results obtained so far in this work reveal that the system behaves apparently like a spin glass around the ordering temperature Tc in both stationary and dynamical aspects, in spite of the frustrated but regular lattice structure.
Magnetic Susceptibility of AuFe: Tg and Curie-Weiss Parameters
Authors: Fisher R. A. , Phillips N. E. , Seto M.
Published: March 2014

The dc field-cooled susceptibilities, χ, of annealed AuFe with nominal concentrations, c, of 0.5, 1 and 2 at.% Fe have been measured in the ranges 2≤T<150K and 1≤H≤50000G. Spin-glass temperatures, Tg, were determined from the cusps in χ at low field. Analysis of the data above 3Tg determined the Weiss constants, Θ, and the effective magneton numbers, p. Assuming S=3/2 for Fe, values of g, the spectroscopic splitting factor, were derived from p.
Kondo Effect and Mutual Interaction
Authors: Sugiyama Tadao
Published: March 2014

Effects of mutual interaction on the forward scattering type s-d exchange interaction have recently been clarified by using the renormalization group method in one-dimension and found that effective strong interaction suppresses the Kondo effect. The above studies are reviewed and moreover, the scaling behavior of the backscattering type s-d coupling is considered.
On the Temperature Hysteresis of Dysprosium Electrical Resistance near Phase Transitions
Authors: Dudáš Ján , Feher Alexander
Published: March 2014

High precision electrical resistance measurements of pure dysprosium were performed in the temperature range from 4.2 K to 300 K on cooling and warming. We have observed the electrical resistance temperature hysteresis at the order-order transition due to existence of the mixed spiral - ferromagnetic phase and that at order-disorder transition, caused by a new intermediate “vortex” magnetic structure.
Low-Temperature Magnetization and Spin-Wave Excitations in Gd
Authors: Nagata Shoichi , Ebisu Shuji , Fujita Eiji , Miyazaki Masatosi , Taniguchi Satoshi
Published: March 2014

The magnetization of Gd has been measured in the temperature 4<T<310 K at constant magnetic field using a vibrating sample magnetometer. We present an exact analysis of spin-wave excitations for Gd in the presence of a magnetic field, H. The low temperature magnetization is found to obey the form : Δσ(T)/σ(0)=BZ(3/2,Tg/T)T3/2+CZ(5/2,Tg/T)T5/2, where B and C are constants, Z(3/2,Tg/T) and Z(5/2,Tg/T) are the characteristic functions of T and H, indicating magnetic field effects.
A 153Eu NMR Study in Diluted Antiferromagnet; EuxSr1-xTe
Authors: Okada K. , Luetgemeier H. , Pieper M. , Zinn W.
Published: March 2014

Insulating diluted antiferromagnets EuxSr1-x Te are studied by a pulsed NMR and high frequency susceptibility measurements for various concentration of x. The experiment is performed at liquid helium temperatures in external field up to 6.5 Tesla. In low field, the spectrum of 153Eu-NMR consists of two peaks for x=95%, 85%, and 75% at 1.2K. For x=95% and 85%, the enchancement factor of NMR becomes maximum at 0.07 Tesla which is just the same value as that of the spin flop transition in antiferromagnetic EuTe. For x=75% and 65%, the transition fields are 0.38 Tesla at 1.2K and decrease slightly with increasing temperatures. In high external field, the resonance spectrum changes gradually from paramagnetic to antiferromagnetic. The experimental results in high external field are compared with a modified mean field theory which is rather good agreement with the data.
Single Domain Magnetic Particles: Magnetic Alignment and Evidence for Verwey Transition from Low Temperature Measurements
Authors: Defranzo A. , Gunther L. , Swanson A. G. , Brooks J. S.
Published: March 2014

In order to make a careful study of ferrofluids of single domain particles of magnetite at low temperatures it is essential to know whether the Verwey transition has taken place. We report the first clearcut evidence for its occurrence as exhibited by the magnetization of a sample cooled down from room temperature to 1K in the presence of an applied field of 8T. Removal of the field leads to a drop in the magnetization associated with a change in the direction of the easy axes in conjunction with the Verwey transition. Previous evidence, based upon the temperature dependence of Mössbauer spectra was quite weak.
Diffusive Soliton in ID Ising-like Antiferromagnet CsCo1-xMgxCl3·H2O
Authors: Goto Takao , Maegawa Satoru
Published: March 2014

The nuclear spin-lattice relaxation time T1 of 133Cs in CsCoCl3·2H2O doped with magnesium with concentration of 2.5% has been measured to study the dynamical behaviors of the soliton (propagative domain-boundary) in ID Ising-like antiferromagnetic system, The experimental results for Ho//c-axis suggest an effect of the impurity on the soliton motion. The temperature dependence of T1 for Ho// a-axis exhibits quite similar features to those for the pure crystal: There appears (T1)min. We show that the diffusive-soliton model gives a good explanation of these experimental results.
Low-Temperature Magnetic and Structural Transitions of the Quasi-One-Dimensional Magnets TMMC and DMMC at High Pressures
Authors: Takeda Kazuyoshi , Suzuki Takamasa
Published: March 2014

The magnetic and structural phase transitions of the quasi-one-dimensional magnetic systems TMMC ((CH3)4NMnCl3; TN=0.84 K) and DMMC ((CH3)2NH2MnCl3; TN=3.60 K) have been studied by the heat capacity measurements at hydrostatic pressures. From the pressure dependence of the Néel temperature, the magnetic Grüneisen constant for the interchain interaction through –Mn– (CH3)4N–Mn– bridge has been conjectured to be much larger than 10 for the intrachain super-exchange interaction through –Mn–Cl3–Mn– bridge. A pressure-induced structural transition has been found in TMMC at pressure p=3.2±0.1 kbar at 4He temperatures. DMMC has been also suggested to experience a structural change in the range 3.2 kbar<p<3.7 kbar.
Very Low Temperature Magnetization of Cu(L–ALA)2
Authors: Calvo R. , Novak M. , Oseroff S. , Symko O. G.
Published: March 2014

Magnetization measurements of Cu (L-ALA)2 from room temperature down to 10 mK show Curie-Weiss behavior at high temperatures, corresponding to a g value of 2.135±0.04 and spin 1/2. AT 0.7 K there is a maximum in the magnetization associated with short range anti- ferromagnetic order. At 0.1 K there is a plateau attributed to frustration and it is followed by an increase in the magnetization below 50 mK due to loose spins. A 1-dimensional anti- ferromagnetic Heisenberg chain is used to explain some of the results.
Successive Phase Transitions in 2D-XY Ferromagnet (C6H5CH2NH3)2CuCl4
Authors: Kimishima Y.
Published: March 2014

The temperature dependence of magnetization M(T) was measured for two-dimensional-XY ferromagnet (C6H5CH2NH3)2CuCl4 by SQUID magnetometer, and two succesive magnetic phase transitions were observed at low effective magnetic field Heff less than about 2.5 Oe. The extrapolated values of upper- and lower transition temperatures Tcu and Tcl were 7.0 and 5.0 K, respectively, at Heff=0. The Tcu and Tcl coincided with each other at about 7.0 K and 2.5 Oe. The experimental results were compared with Pokrovsky and Uimin's theory on the spin wave type fluctuations in 2D-XY ferromagnet, and the scaling dimension Δ at Tcu was estimated experimentally as Δ≦0.36. This result is in agreement with Δ(Tcu)=1/π derived from the above theory.
He II Thermal Counterflow near Superfluid Turbulent Transition
Authors: Yamaguchi Minoru , Fujii Yoshiko , Kishida Masayuki , Nakamura Masaki
Published: March 2014

Thermal counterflow of He II in a circular glass capillary has been studied near a transition from laminar flow to turbulent flow. In order to study effects of edge shape of a capillary on the vortex nucleation a sharp edged capillary (tube I) and a tapered capillary (tube II) were used. The temperature difference (ΔT) across the tube was measured precisely using a thermocouple connected to a SQUID detector. The vortex line density Lo was obtained from ΔT data. The critical value of (Lo
1/2d)c (d: tube diameter) at the transition for tube II was smaller than that for tube I. The spontaneous periodic fluctuation of ΔT was observed near the transition.
Satellite Phonon Absorption Lines above the 875 GHz Resonance of Interstitial Oxygen in Silicon
Authors: Dittrich E. , Scheitler W. , Eisenmenger W.
Published: March 2014

Acoustic phonon spectroscopy with superconducting tunneling junctions as phonon generator and detector revealed a large number of sharp absorption lines between 875 GHz (oxygen resonance) and
1.35 THz for silicon doped with interstitial oxygen (Si:0i). The strength of these lines scales with the square of the oxygen concentration ranging from 1017 to 1018 cm-3. Under mechanical stress the lines show a frequency shift almost identical to the main oxygen resonance at 875 GHz as well as to the also observable isotope resonance. These satellite absorption lines are therefore discussed as 0i–0i neighbour interaction. This is supported by the influence of annealing.
Conductance of Two-Dimensional Quasicrystals
Authors: Ueda Kazuo , Tsunetsugu Hirokazu
Published: March 2014

Conductance of two-dimensional quasicrystals (2D-Fibonacci lattice and Penrose lattice) is discussed with the use of multichannel Landauer formula. For the 2D-Fibonacci lattice there is a transition from the regime of finite spectral measure for a weak potential to the regime of zero measure for a strong potential. The conductance of the 2D-Fibonacci lattice fluctuates with the system size and even in the strong potential regime the fluctuation is not less than e2/h. The conductance of the Penrose lattice is discussed in the light of these new findings.
Dielectric and Structural Studies of Trifluoromethane Monolayers on Boron Nitride and Graphite
Authors: Wiechert H. , Maus E. , Knorr K.
Published: March 2014

Dielectric and X-ray diffraction measurements have been performed in the search for two-dimensional electrically ordered phases in CF3H monolayers adsorbed on boron nitride (BN) and graphite. Two distinct crystalline phases have been found: an orientationally disordered triangular incommensurate high-temperature phase and a uniaxially compressed low-temperature phase, in which the molecules show staggered orientations of the dipole moments leading to states of antiferroelectric (T < 75 K) or ferroelectric (T < 50 K) nature. A phase diagram of CF3H monolayers is proposed.
Hydrostatic-Pressure Derivative of Tm and Tc in A15 Compounds
Authors: Ota S. B.
Published: March 2014

The behaviour of the hydrostatic-pressure derivatives (dTm/dp) and (dTc/dp), in the A15 compounds has been investigated theoretically. The cubic-to-tetragonal transformation has been assumed to be driven by Jahn-Teller effect involving the narrow electronic band that arises out of the doubly degenerate Γ12 state near the Fermi energy. The electrons in this band are also assumed to contribute to the superconducting state which has been described by the Bardeen-Cooper-Schrieffer theory. It has been argued that Tc chiefly depends on the electronic density of states at the Fermi energy, which is altered significantly by the variation of Tm with hydrostatic pressure. It has been shown that the sign of (dTc/dp) is opposite to that of (dTm/dp) and (dTc/dp) is an order of magnitude lower than (dTm/dp). These are in agreement with the experimental results.
X-ray Diffuse Scattering in “Premartensitic Phase” of A–15 Compounds
Authors: Kamigaki Kousei , Sakashita Hirofumi , Terauchi Hikaru , Toyota Naoki , Fukase Tetsuo
Published: March 2014

The origin of “premartensitic state” of Nb3Sn with A–15 type structure has been investigated by x-ray diffraction technique. The diffuse scattering along the [112̄] direction around the (666) reflection has been found above Tm (martensitic transformation temperature) and develops with lowering temperature to Tm. The origin of the diffuse scattering is associated with “tweed pattern” observed by electron microscopy.
Properties of Superconducting NbN and NbCN Single Crystal-Like Thin Films Grown on Single Crystal Substrates
Authors: Francavilla T. L. , Skelton E. F. , Pande C. S. , Wolf S. A. , Hein R. A.
Published: March 2014

Single crystal-like films of NbN and NbCN were epitaxially grown on single crystal substrates of [100]-oriented MgO and [101̄0]-oriented sapphire by rf-reactive sputtering. The films consist of fine grain crystallites slightly misaligned with respect to each other, but in overall alignment with the substrate in the case of MgO. The superconducting transition temperatures of both NbN and NbCN films grown on MgO were slightly lower than those of films simultaneously grown on companion sapphire substrates.
Superconducting Properties in Mo6Se8-xSx
Authors: Furuyama Masafumi , Kobayashi Norio , Noto Koshichi , Muto Yoshio
Published: March 2014

Upper critical magnetic field Hc2 was measured on several single crystals of the Chevrel phase compound Mo6Se8-xSx with a wide concentration range (X=0.0, 0.2, 0.5, 0.7, 1.0, 1.5, 2.0, 3.0, 4.0 nominally). An enhancement of Hc2 over the Werthamer-Helfand-Hohenberg (WHH) theoretical value was observed for all samples. The temperature dependence of the renormalized hc2 is expressed by the same universal curve. On the other hand, it seems that the enhancement of hc2 is independent of the strength of the electron-phonon interaction, because the electron-phonon interaction changes from strong coupling to weak one.
Are Pb–Bi Ordering Waves Instrumental for the Metal-Insulator Transition in BaPb1-xBixO3?
Authors: Weber Werner
Published: March 2014

We propose that the metal-semiconductor transition in the BaPb1-x
Bi
x
O3 alloy system in caused by a cooperative effect of both `breathing' type charge density waves and ordering waves on the Pb-Bi lattice. The wavevectors Q are nesting vectors over the proper Fermi surfaces and should increase with Bi concentration x. They should be observable in the diffuse elastic scattering.
Electron Tunneling Measurements of High Tc Compounds Using Break Junctions
Authors: Moreland John , Goodrich L. F. , Ekin J. W. , Capobianco T. E. , Clark A. F.
Published: March 2014

We report on the break junction technique and its application to the high Tc superconductors LaSrCuO and YBaCuO. In this technique, bulk samples are fractured and the freshly fractured surfaces adjusted to form a tunneling junction with vacuum or liquid helium as the insulating barrier. Precise mechanical adjustment permits the study of electron tunneling phenomena between pieces of a bulk superconductor. The current voltage characteristics of these break junctions are variable indicating sample inhomogeneity. However, some junction settings result in the more familiar quasiparticle signatures in the current voltage characteristics. Low leakage junctions indicate the presence of a sharp superconductive energy gap as well as large variations in junction conductance above the gap edge in both materials.
3.5 inch Magneto-optical Disk Memory System using Readout Technique from Transmitted Light and NdDyFe-based Recording Material
Authors: Kogure Shigeru , Yonekubo Masatoshi , Ota Kazuhiko , Nebashi Satoshi , Hirasaki Michiya
Published: March 2014

A low-cost 3.5 inch magneto-optical disk memory using the readout technique from transmitted light and the new recording material has been developed and confirmed to work as the peripheral system to a personal computer.
Novel 1-beam-overwriting Method for Phase-change Erasable Disk
Authors: Yasuoka Hiroshi , Ojima Masahiro , Terao Motoyasu , Nishida Tetsuya
Published: March 2014

In-Se-Tl-Co compound is found to have short crystallization time of 60ns and high crystallization temperature of 320°C. When recording at a low linear velocity on this material, spiky peaks appear in the readout signals and pre-recorded data can not be completely erased after overwriting with 1 circular laser beam spot. The phase changing process is analysed by a crystallization model and computer simulation of the recording film temperature. Based upon these studies, a new 1-beam-overwriting scheme is proposed, in which a high power laser beam continuously irradiates the recording film, except for short time intervals corresponding to the signals to be recorded. This 1-beam-overwriting is demonstrated to provide high quality overwriting characteristics.
Focus Sensing Characteristics of the Pupil Obscuration Method for Continuously Grooved Disks
Authors: Irie Mltsuru , Fujita Teruo , Shinoda Masahisa , Kondo Mitsushige
Published: March 2014

This paper presents a Fourier optic model for calculating focus error signals derived with the pupil obscuration method for optical disk drives (ODD). In continuously pregrooved disks, the focus error signals in random accessing are varied by the diffracted beam. We examine the influence of the diffracted beam on the focus error signals and the focus sensing characteristics. The theoretical analysis using this model shows that the fluctuation of the focus error signal can be suppressed to within 0.2µm peak-to-valley at the focus, and that the focus offset produced by an axial displacement of the split detector is about 0.3µm for a displacement of 100µm, in which the numerical aperture of the objective lens and the sensor lens are 0.5 and 0.053, respectively. Then, we make clear that the linear-zone width can be expanded from 2µm to 8µm when the boundary-area width of the split detector increases from 10µm to 50µm. The theoretical results are compared with experimental results and they correspond well with each other.
Ba-Ferrite Magneto-optical Recording Media
Authors: Kaneko Yujiro , Sawada Yasuo , Ohmi Fumiya , Miyamoto Isao , Watada Atsuyuki
Published: March 2014

We have studied on the application of Ba-ferrite(BaFe12O19) to magneto-optical recording. It was found that CoTi substituted Ba-ferrite(BaCoxTixFe12-2xO19) films on GGG single crystals had Faraday rotation of 0.9deg/ µ m(λ=780nm) and Curie temperature of 320°C at X=0.9. And CoTi substituted Ba-ferrite films with the perpendicular magnetic anisotropy were obtained on glass substrate by using (111) orientated NiZn-ferrite(NixZn1-xFe2O4) films for under layer. From these results, Ba-ferrite magneto-optical recording medium which constitution is glass substrate, NiZn-ferrite under layer, CoTi substituted Ba-ferrite magnetic layer and stripe-shaped metal reflective layer for the guide tracks, is proposed from the optimization of each layer.
Crystallization Properties and Operative Regions of Erasable Optical Disk using Chalcogenide Films
Authors: Okuda Masahiro , Rhee J. C. , Fusong J. , Naito Hiroyoshi , Matsushita Tatsuhiko
Published: March 2014

Measurements of the index n and the activation energy E in the Avrami equation from the reflectivity change and DSC enable us to discuss the crystallization properties of chalcogenide films and the operative regions of the erasable optical disk. The reasonable optical disk material is necessary to have the high melting temperature Tm and the larger activation energy E of crystallization. In order to increase Tm and E, it is desirable that, in the Ga-Se-Te systems, the increase of Ga content is necessary.
Pregrooved Disk Formed by Dry Etching Technique
Authors: Miyagi Masami , Iwasawa Akira , Yamazaki Hiroki
Published: March 2014

A pregrooved disk is fabricated by dry etching of the silicon oxide film deposited on the glass substrate. The disk has a uniform groove depth and a smooth surface, which enables stable tracking operations and high quality playback of prepits signal.
Photochromic Mechanisms in Deposited Spiran Thin Film
Authors: Morinaka Akira , Yoshida Takashi , Funakoshi Nobuhiro
Published: March 2014

A study of photochromism in vacuum deposited spiran film which shows reversible change which occurs between two of three phases, is conducted. The colored form of spiran is considered to be stabilized by hydrogen bonding of neighboring molecules. Infrared spectrum analysis clarifies that this stabilized colored form is attributed to the cisoid form.
Polymer Substrates for Optical Discs
Authors: Hennig Jürgen
Published: March 2014

PMMA and PC are widely used as substrate materials for optical discs. Because of its barrier effect inorganic glass is sometimes preferred for DRAW and E-DRAW information carriers. PMMA is little sensitive to orientation and stress birefringence but absorbs water up to 2 wt.-%, thus PMMA substrates being prone to warping. With PC the situation is just the other way round. So we are looking for a polymer which combines low optical anisotropy with reduced water absorption. In view of the additivity of bond polarizabilities we might be able to solve the anisotropy problem via copolymerization and/or blending by compensating positive and negative anisotropies where molecular structure and compatibility are important factors. Process improvements including injection and compression molding as well as extrusion to keep the orientation low compete strongly with these chemical developments. Reduced water absorption may.be achieved by copolymers MMA/St and MMA/CHMA or by special polyolefines and partly by epoxy resins.
Change in Birefringence in Polycarbonate Substrates under Operating Environments
Authors: Nakada M. , Saitoh M. , Toki K. , Gokan H.
Published: March 2014

Long term birefringence change in polycarbonate substrate has been studied at high temperature or with stress, and the equation relating the birefringence change rate with temperature or stress was experimentally determined. At high temperature, the change in birefringence was found to be logarithmic in time and can be explained in terms of a stress relaxation. The effect of stress on the change in birefringence was analyzed from a viscoelastic point of view, and it was found that the change in birefringence was proportional to the 0.31 power of time. It is concluded, from the evaluation of the birefringence change under operating environment, that a polycarbonate substrate has high stability in regard to birefringence when used for magneto-optical disks.
Predictors of performance on the National Board of Chiropractic Examiners Parts I and II*
Authors: McCall Angela R. , Harvey Richard D.
Published: March 2014

Objective

The purpose of this study was to examine predictors for success on Parts I and II of the National Board of Chiropractic Examiners (NBCE) written examinations.

Methods

Two validity studies were conducted to examine the criterion validity of Logan College assessments for Part I and II NBCE scores. Both studies consisted of a longitudinal design to examine the validity of entrance grade point average (GPA), in-program chiropractic course content GPA, and an institutional practice exam on Parts I and II of the NBCE.

Results

Analyses revealed that Part I GPA and practice exam scores combined accounted for 72% of the variance within Part I NBCE scores. Furthermore, every subtest of the Part I NBCE could be reliably predicted by course performance. In the 2nd study, Part I GPA, Part I NBCE score, and Part II GPA accounted for 75% of the variance within Part II NBCE scores.

Conclusions

Internal training and educational assessments (eg, course grades and practice exams) proved to be strong determinants of NBCE performance above and beyond initial levels of preparedness, thus validating the impact of the chiropractic curriculum on NBCE test achievement.
Some Optimization Models and Techniques for Electric Power System Short‐term Operations
Authors: Sun Andy , Phan Dzung T.
Published: March 2014

This article introduces modern optimization models and solution methods for two fundamental decision‐making problems in electric power system short‐term operations, namely the optimal power flow (OPF) problem and the unit commitment (UC) problem. This article reviews basic formulations and surveys some of the most recent advances, including global optimization techniques for exact solution of the OPF problem, adaptive robust optimization models for the UC problem under uncertainty of renewable generation and demand‐side response, contingency analysis for large‐scale power systems, and distributed optimization schemes for decentralized operation.
Discrete Optimization with Noisy Objective Function Measurements
Authors: Hill Stacy D.
Published: March 2014

The problem of optimizing noisy objective functions over a discrete set—stochastic discrete optimization—occurs in a wide variety of practical applications. This article gives a general formulation of such optimization problems and indicates some of the diverse applications. It also describes several classes of methods for solving such problems and discusses some of their important features such as expected performance and computational efficiency.
Economic Inclusion and Financial Education in Culturally Diverse Communities: Leveraging Cultural Capital and Whole‐Family Learning
Authors: Robles Bárbara J.
Published: March 2014

This chapter focuses on the importance of approaching economic education pedagogy as a whole‐family learning process, especially in high immigrant and culturally diverse neighborhoods.
Reconstruction of Vascular Structure with Multicellular Components using Cell Transfer Printing Methods
Authors: Lee Yu Bin , Jun Indong , Bak Seongwoo , Shin Young Min , Lim Youn‐Mook , Park Hansoo , Shin Heungsoo
Published: March 2014

Natural vessel has three types of concentric cell layers that perform their specific functions. Here, the fabrication of vascular structure is reported by transfer printing of three different cell layers using thermosensitive hydrogels. Tetronic–tyramine and RGD peptide are co‐crosslinked to prepare cell adhesive and thermosensitive hydrogels. The hydrogel increases its diameter by 1.26 times when the temperature reduces from 37 °C to 4 °C. At optimized seeding density, three types of cells form monolayers on the hydrogel, which is then transferred to the target surface within 3 min. Three monolayers are simultaneously transferred on one substrate with controlled shape and arrangement. The same approach is applied onto nanofiber scaffolds that are cultured for more than 5 d. Every type of monolayer shows proliferation and migration on nanofiber scaffolds, and the formation of robust cell–cell contact is revealed by CD31 staining in endothelial cell layer. A vascular structure with multicellular components is fabricated by transfer of three monolayers on nanofibers that are manually rolled with the diameter and length of the tube being approximately 3 mm and 12 mm, respectively. Collectively, it is concluded that the tissue transfer printing is a useful tool for constructing a vascular structure and mimicking natural structure of different types of tissues.
Controlled Growth of Single‐Walled Carbon Nanotube Networks by Catalyst Interfacial Diffusion
Authors: Yick S. , Han Z. J. , Ostrikov K.
Published: March 2014

Single‐walled carbon nanotubes are promising for many applications due to their unique mechanical, electrical and optical properties. However, their application has been hampered so far by the lack of controllability in the direct growth process, in particular the size and chirality distributions which inevitably lead to a large variability of their electronic structures. Here we demonstrate the effect of catalyst interfacial diffusion using a tri‐layered Al2O3/Fe(Mo)/Al2O3 catalyst and achieve the effective control of density, diameter, and conductivity of the as‐grown nanotube networks. This method modulates the thickness of the top Al2O3 layer which affects the diffusion of Fe atoms and subsequently the formation of catalyst nanoparticles. We show that the tri‐layered catalyst allows one to vary the density of networks from 0.18 to 35 tubes/μm2, the diameter from 1.36 to 1.72 nm, and the metallic fraction from 20% to 45%. It may thus represent a promising strategy for tailoring the properties of as‐grown carbon nanotube networks for their proposed applications.