Journal of the Physical Society of Japan
Online ISSN : 1347-4073
Print ISSN : 0031-9015
ISSN-L : 0031-9015
Volume 66, Issue 11
Displaying 1-50 of 65 articles from this issue
  • Ken–ichi Matsuba, Kazuhiro Nozaki
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 11 Pages 3315-3317
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    It is shown that the renormalization group method does not necessarily eliminate all secular terms in the perturbation series to partial differential equations.Also, choosing a subspace of renormalizable secular solutionscorresponds with setting scales of independent variables inthe reductive perturbation method.
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  • Mitsuyoshi Tomiya, Naotaka Yoshinaga
    Subject area: Classical and quantum physics: mechanics and fields.
    1997 Volume 66 Issue 11 Pages 3318-3321
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    An example other than the hyperbolic billiard, the mode fluctuation of which shows Gaussian distribution, is presented. It is the Bunimovich's stadium billiard where the mode fluctuation is obtained by eliminating the semiclassical contribution of the bouncing ball modes from the spectral staircase function. The mode fluctuation without this elimination shows the skewness which considerably agrees with semiclassically evaluated predictions.
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  • Minoru Takahashi, Eric D. Williams
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 11 Pages 3322-3325
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    A disconnection transition is aphase transition which accompanies a change in the connectedness ofthe fermi sea. The existence of such a transition is established in thecontext of a one-dimensional interacting model. The model considered is an extension of the deltafunction bose gas in which its fourth order conservation law is addedto the original hamiltonian. For low density, the ground state of themodel consists of two separated fermi seas and there are two distinctbranches of excitations. At a critical density, one branch ofexcitations disappears, and there is a second order phase transition toa single fermi sea ground state.
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  • Ken Sekimoto, Shin–ichi Sasa
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 11 Pages 3326-3328
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    When the process of a system in contact with a heat bathis described by the classicalLangevin equation, use of the method of stochastic energetics [K. Sekimoto: J. Phys. Soc. Jpn. 66 (1997) 1234]enables us to derive the form of Helmholtz free energy and thedissipation function of the system.We are able toprove that the irreversible heat Qirr and the time lapseΔ t of an isothermal process obey the complementarity relation, Qirr , Δ t≥q kBT , Smin, where Smin depends on the initial and the final values of the control parameters, but does not depend on the pathway between these values.
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  • Yoshiki Hidaka, Jong–Hoon Huh, Ken–ichi Hayashi, Michael I ...
    Subject area: Fluid dynamics.
    1997 Volume 66 Issue 11 Pages 3329-3332
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The systematic experimental study of direct transition “nonconvective state --- spatiotemporal chaos” in electrohydrodynamic convection of a homeotropically aligned nematic is carried out. The transient patterns, both below and beyond the Lifshitz point, are studied and classified. The patterns initially correspond to oblique and normal rolls, respectively. In all the cases the transition to chaos undergoes slow spatiotemporalmodulations of the local roll orientation. This results in the finaldynamical patterns isotropic on large spatial scales. The dynamics of thefinal patterns are also studied with a quantitative analysis of the powerspectra of turbulent modes and their autocorrelation functions. Theexponential decay of the correlations in time is proved.
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  • Koji Nozaki, Takashi Yamamoto, Masamichi Hikosaka
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 11 Pages 3333-3336
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The details of the molecular layer stacking in the low-temperature ordered (LO) phases of n-alkane with an odd carbon number were investigated by calculating the layer stacking energy.In order to express the layer stacking, a parameter Δ b is defined as the relative shift of the upper layer to the lower layer along the b-axis.The layer stackings with two specific positive and negative Δ b values (Δ b=+b_p, -b_n) have minimum energy. In phases I and V, the energy at the positive Δ b is lower than that at the negative Δ b; the layer stacking with positive Δ bis considered to be more stable. While in phase IV, the energies at both shifts Δ b areequal; the stabilities of the two stackings are the same.The values of relative shift with the minimum energies in each LO phaseapproximately correspond to those values determined using X-ray diffraction.
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  • Jun Kawai, Kouichi Hayashi, Yasuhiro Awakura
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 11 Pages 3337-3340
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Aluminum K-LL radiative Auger X-ray fluorescence spectra of AlPO4 and Al2O3 powders are measured using an X-ray fluorescence spectrometer for elemental analysis. We demonstrate that the Fourier transform of the oscillation in the radiative Auger spectra has information similar to that of the extended X-ray absorption fine structure (EXAFS). The Al--O distances in AlPO4 and Al2O3 are determined by the radiative Auger X-ray fluorescence spectra. The accuracy of the Al--O bond length is within 0.03, Å.
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  • Toshiro Tanaka, Kazuo Miyatani
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 11 Pages 3341-3343
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The low-temperature X-ray diffraction study and the magnetization and the electrical resistivity measurements, were performed on the single phase polycrystalline spinel CuV2S4. The crystal structure was confirmed to have a normal cubic spinel structure with a=9.809, Å and u=0.382 at 300, K. The splitting of the (400) plane was observed below 90, K, resulting in the coherent cubic to tetragonal phase transition with c/a=0.997. Any additional lines due to the charge density wave were not observed. The tetragonality c/a and the deformation potential of spinels fairly well explained the transition temperature of 90, K and the splitting of the 3d(dε ) orbit of about 15, meV. Thus, the phase transition is explained by the cooperative Jahn-Teller effect of V3+(3d2) in the octahedral site.
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  • Wilson Agerico Diño, Hideaki Kasai, Ayao Okiji
    Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
    1997 Volume 66 Issue 11 Pages 3344-3347
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    We show that the recently observed nonmonotonous dependence of theadsorption probability of H2/Pd(111) on the initial rotational statej of the impinging H2 can be accounted for by considering the twofactors- Steering (Dynamical Reorientation) and Rotational-Translational Energy Transfer (Bond-Length Extension), and the importance of the incidence energy (velocity) of the impinging hydrogen molecule. Furthermore, we show that considerable isotope effects can be observed for the j-dependence of the adsorption probability of hydrogen on Pd.
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  • Tadao Kasuya
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3348-3351
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Various unusual properties in the anomalous superconductor URu2Si2 in the normal state have been studied based on the standpoint of pair Jahn-Teller distortion. The pair distortion occurs well above the ordering temperature and thus the transition for the pair ordering is weak. Due to an inherent characteristic of pair ordering, the ordering is not perfect but includes unpaired U atoms. This is the origin of the weak antiferromagnetic ordering with the moment of 0.01--0.04, μ B/U and a heavy fermionlike behavior. No Kondo effect is observed. To confirm the above model, dilute alloy systems have also been studied and it is shown that all of them can be explained by a common model consistent with that of URu2Si2. The proposed two-channel Kondo state for dilute U atoms in the ThRu2Si2 system was shown to be unacceptable.
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  • Hitoshi Seo, Hidetoshi Fukuyama
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3352-3355
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The nature of the insulating ground state in quasi-two-dimensional organic conductor λ-(BETS)_2GaXzY4-z, where the existence of a spin gap is suggested by susceptibility measurement, has been studied theoretically. Hartree-Fock calculations at absolute zero temperature show that if the on-site Coulomb interaction exceeds some critical value, then antiferromagnetic spin ordering emerges and eventually leads to an insulating state which can be considered as a two-dimensional localized spin system. Based on the quantum Monte Carlo simulations of Katoh and Imada, we will show that this system locates near the boundary between the antiferromagnetic phase and the spin gap phase, so that experimental facts can be explained.
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  • Nobuko Kobayashi, Masao Ogata
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3356-3359
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    We have performed a mean field calculation in order to determine the ground state of a modified Hubbard model of a quarter-filled one-dimensional chain. A phase diagram is obtained as the values of the elastic constant of the chain and the on-site Coulomb energy are varied. Our result supports the experimental report concerning (TMTSF)2PF6 that an X-ray observation has confirmed a coexisting phase of 2kF CDW and 2kF SDW.
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  • Ryuta Yagi, Shun–ichi Kobayashi
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 11 Pages 3360-3362
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    We observed an insulator-superconductor transition in small Josephson junctions shunted by ohmic resistors (Rs). The transition took place when Rsq(=h/4e2) for junctions with a tunneling resistance larger than Rq.
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  • Michiyasu Mori, Masao Ogata, Hidetoshi Fukuyama
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 11 Pages 3363-3366
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Possible modification of the quantized conductance of a one-dimensional doped Mott insulator, where the Umklapp scattering plays an important role, is studied based on the method by Maslov, Stone and Ponomarenko. At T=0 and away from half-filling, the conductance is quantized as g=2e2/h and there is no renormalization by the Umklapp scattering process. At finite temperatures, however, the quantization is influenced by the gate voltage and temperature.
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  • Akihiro Himeda, Masao Ogata, Yukio Tanaka, Satoshi Kashiwaya
    Subject area: Superconductivity.
    1997 Volume 66 Issue 11 Pages 3367-3370
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The microscopic structure of vortex cores in high-Tc superconductorsis studied using the two-dimensional t-J model under a uniformly applied magnetic field. The spatial dependence of the pair potential is calculated for various doping rates via the Gutzwiller approximation, in which the effect of strong correlation is taken into account. The results show that, in the wide range of doping rates, the pair potential has d-wave nature and the local density of states near the core center shows a zero-energy peak. However, in the low-doping region, an s-wave component is locally induced around the core and the zero-energy peak splits into two levels. This doping-dependence is characteristic of the t-J model. Our results give a possible explanation for the experimental observation by scanning tunneling spectroscopy [Phys. Rev. Lett. 75 (1995) 2200]which demonstrates the splitting of the local density of states.
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  • Kazuhiko Kuroki, Ryotaro Arita, Hideo Aoki
    Subject area: Superconductivity.
    1997 Volume 66 Issue 11 Pages 3371-3374
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The ground state of a one-dimensional Hubbard model with next-nearest neighbor hopping (t') as well as nearest-neighbor hopping (t) is numericallyinvestigated at half-filling. A quantum Monte Carlo result shows a slowly decaying pairing correlation for a sizeable interaction strength (U ≤ 2t), while the system is shown to become insulating for larger U>U_C-- 3t from a direct evaluation of the charge gap with the density-matrix renormalization group method. The results give a quantitative confirmation of Fabrizio's recent weak-coupling theory which predicts a transition from a superconductor into an insulator at a finite U.
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  • Masao Ogata
    Subject area: Superconductivity.
    1997 Volume 66 Issue 11 Pages 3375-3378
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    A new superconducting phase is found in the two-dimensional t-J model near half-filling within the mean-field theory and Gutzwiller approximation. This state has a spatial dependence of order parameters which is interpreted as a mixing of the extended s-wave component with the finite total momentum in addition to the dx2-y2-wave symmetry. The origin of this peculiar pairing is investigated. There is no node in the gap function in the new state and possible experimental consequences are discussed.
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  • Atsuhiro Kitazawa, Kiyohide Nomura
    Subject area: Magnetic properties and materials.
    1997 Volume 66 Issue 11 Pages 3379-3382
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Based on the universality concept, we study the S=3/2 and S=2 bond-alternating spin chains numerically. In previous papers, the phase diagram of the S=1 XXZ spin chain with bond alternation was shown to reflect the hidden Z2× Z2 symmetry. For the higher S Heisenberg spin chain, the successive dimerization transition occurs, and for anisotropic spinchains the phase structure will be more colorful than the S=1 case. Using recently developed techniques, we show directly that the phase structure of the anisotropic spin chains relates to the Z2× Z2 symmetry.
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  • Yutaka Itoh, Masahiro Matsumura, Hideki Yamagata
    Subject area: Magnetics resonances and relaxations in condensed matter; MÖssbauer effect.
    1997 Volume 66 Issue 11 Pages 3383-3386
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The doping dependence of low-frequency spin dynamics is discussed from a viewpoint of the self-consistently renormalized spin-fluctuation theory for the experimental planar Cu nuclear spin-lattice relaxation rate 1/T1 in the doped high-Tc Cu oxides, La2-xSrxCuO4 (x=0.06, 0.15 and 0.20). We report that the crossover temperature T* of T1T deviating from the high-T Curie-Weiss law increases with reduced carrier density. We found that the doping dependence of T* is not consistent with the current spin-fluctuation theories in which the actual metal-insulator transition is regarded as the disorder-to-order transition. The present suppression of the staggered spin fluctuation is an anomaly near half-filling, inclusive of the pseudo spin-gap.
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  • Katsuhiko Fukasaku, Kyozaburo Takeda, Kenji Shiraishi
    Subject area: Biophysics.
    1997 Volume 66 Issue 11 Pages 3387-3390
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The electronic structures of protein nanotubes, which areformed by the periodical stacking of cyclo-peptide-rings (CPRs), aretheoretically investigated in terms of ab initiocalculations. The interring interaction is caused through theinterring H bonds, when CPRs are periodically stacked. Thisinteraction has a potential to delocalize electrons and holes towardthe tube axis, so that the band conduction occurs throughout theinterring H bonds.
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  • Zengo Tsuboi
    Subject area: Mathematical methods in physics.
    1997 Volume 66 Issue 11 Pages 3391-3398
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    It is known that a family of transfer matrix functional equations, the T-system, can be compactly written in terms of the Cartan matrix of a simple Lie algebra.We formally replace this Cartan matrix of a simple Lie algebra with that of an affine Lie algebra, and then we obtain a system of functional equations different from the T-system. It may be viewed as an Xn(a) type affine Toda field equation on discrete space time. We present, for An(1), Bn(1), Cn(1), Dn(1), An(2) and Dn+1(2), its solutions in terms of determinants or Pfaffians.
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  • Hidetomo Hirao, Sachiko Koseki, Hiroshi Takano
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 11 Pages 3399-3405
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Relaxation modes and rates of a single polymer chainwith the excluded volume interaction is studiedby molecular dynamics simulations.The variational method for the estimation of the relaxation modes and ratesproposed by Takano and Miyashita[J. Phys. Soc. Jpn. 64 (1995) 3688] is generalized to cases where the detailed balance condition is not satisfiedand applied to the results of the present simulations.The relaxation modes and rates estimated by the generalized methoddescribe the behaviors of the autocorrelation functionsof relative velocities and relative positions of the segments well.For a polymer chain with N segments, the behavior of the pth slowest relaxation rate λ_pwith p/N << 1 is consistent with the theoretical predictionλ_p ∝ (p/N)2ν + 1, where ν isthe exponent for the size of a polymer chain in good solvent.
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  • Hirotaka Tominaga, Hirokazu Fujisaka, Wolfram Just
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 11 Pages 3406-3410
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The chaotic motion of a particle in a rotationally symmetricMexican hat potential subjected to a periodic external force is found to undergo a symmetry--breaking instability as the forcing amplitude is increased. Below the threshold the motion is confined to onespace dimension, whereas beyond the instability the particle starts to move in both dimensions. At the onset the system exhibits the so--called on--off intermittency.The statistical characteristics on both sides of the bifurcation point are studied in comparison with previous investigations of on--off intermittency.
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  • Seiji Miyashita
    Subject area: Statistical physics and thermodynamics.
    1997 Volume 66 Issue 11 Pages 3411-3420
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Thermodynamic properties of the three dimensional six-state clock model are investigated. From temperature dependences of the specific heat and the spontaneous magnetization, the discreteness of the model seems irrelevant at high temperature region of the ordered phase, while it is definitely relevant at low temperature region.Studying the size dependence of distributions of the magnetization, however, it turns out that the discreteness is always relevant in the ordered state.The critical exponents of the model are also investigated and it is confirmed that the model belongs to the universality class of the three dimensional XY model.
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  • Ramendra Nath Majumdar
    Subject area: Nuclear structure.
    1997 Volume 66 Issue 11 Pages 3421-3423
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The neutron strength distributions of the two high-spin 1k15/2 and 1l19/2 unbound states of 209Pb have been viewed in detail within the formalism of the Core-Polarisation effect where the effect of interaction of the neutron shell-model states of 209Pb with the collective vibrational states from the giant resonances has been taken into consideration. The theoretical results have been discussed in the light of our previous works on 1j13/2, 2h11/2 and 1k17/2 neutron orbitals of 209Pb. Side by side available theoretical work on the continuum shell-model states has been compared with the present theoretical calculations.
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  • Tomohiko Ishii, Rika Sekine, Toshiaki Enoki, Eizo Miyazaki, Takayuki M ...
    Subject area: Electronic structure of atoms and molecules: theory.
    1997 Volume 66 Issue 11 Pages 3424-3433
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    We investigate the electronic structure of AuCl3 graphite intercalation compounds by means of discrete variational (DV)-Xα molecular orbital calculation and ultraviolet photoelectron spectra (UPS). DV-Xα calculation of the Au2Cl6 intercalate reveals the importance of relativistic effect due to the presence of heavy Au atoms. The terminal Cl 3p orbital contributes mainly to the lowest unoccupied molecular orbital (LUMO) of Au2Cl6 molecule in addition to the minor contribution of the Au 5d component. The calculation of (Au2Cl6)-0.5, which is considered to be intercalate species realized in graphitic galleries through charge transfer from graphite, suggests that the Au2Cl6 intercalate band is located at around the Fermi level EF as well as the graphitic π-band. As a consequence, the density of states at EF is 2-3 times larger than that expected only by the graphitic π-band, which is consistent with optical reflectance, magnetic susceptibility, and the electronic specific heat. The small hump around EF in the UPS of AuCl3-GIC is considered to be associated with the intercalate band. The overlap population analysis suggests the bonds between gold and chlorine atoms in Au2Cl6 become weaker when the 0.5 electron transfer from graphitic π-band to Au2Cl6 molecule. Therefore, the interatomic distances in the Au2Cl6 molecule are found to become elongated, consistent with the experimental results of the Raman spectra.
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  • Hideo Yahata
    Subject area: Fluid dynamics.
    1997 Volume 66 Issue 11 Pages 3434-3443
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Thermal convection of a fluid contained in a two-dimensional vertical rectangle under a uniform horizontal temperature gradient is studied with the aid of numerical simulations of the governing equations of motion. The velocity is assumed to satisfy the rigid boundary conditions (b.c.) on all the boundary walls whereas the temperature satisfies the isothermal and the adiabatic b.c. on the vertical and the horizontal side walls respectively. The Prandtl number Pr of the fluid is Pr = 0.71 and the aspect ratio A of the rectangle is taken as A=6. With increase of the Grashof number G characterizing the intensity of the thermal gradient, the motion successively exhibits different temporal behavior: steady \longrightarrow periodic \longrightarrow quasi-periodic with two fundamental frequencies \longrightarrow chaotic where the transition to chaos is caused by the disruption of the T2-torus due to the phase-locking. The spatial patterns associated with the above temporal oscillations are also given using the contour plots of the temperature field of the convection.
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  • Ettore Minardi
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 11 Pages 3444-3452
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    States of stationary magnetic entropy are connected by a similarity transformation that describes a poloidal flux-conserving rearrangement of the equilibrium and a global invariance of the magnetic structure. It is conjectured that the only permissible states in the confinement zone of a tokamak are magnetically similar states of stationary entropy, and that the physical properties of transport in these states are the same, apart from a similarity transformation. This conjecture, which establishes a connection between transport and magnetic structure, allows one to write down a power balance equation in the confinement zone that describes the temperature evolution in transient processes driven by rapid changes of the magnetic equilibrium. In the present paper the following experimental facts are considered in the light of this equation: the sensitivity of the core temperature of the tokamak to edge perturbations of the current channel, the nonlocal, nondiffusive behaviour of heat pulses from the mixing zone observed in heat modulated experiments and the global temperature evolution observed immediately after the L-H transition.
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  • Maria V. A. P. Heller, Raul M. Castro, Ibere L. Caldas, Zoezer A. Bras ...
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 11 Pages 3453-3460
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Measurements of poloidal and radial magnetic field, density, potential, and temperature fluctuations were simultaneously performed at the plasma edge of the TBR tokamak using a especially constructed probe system. Direct cross spectral and bispectral analyses of these fluctuations showed evidences of both linear and nonlinear coupling between electrostatic and magnetic oscillations. Resonances created by external perturbing magnetic fields slightly reduced the linear coupling and almost entirely suppressed the quadratic coupling.
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  • Yasuo Yoshimura, Teruo Saito, Yasuhito Kiwamoto, Yoshinori Tatematsu, ...
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 11 Pages 3461-3469
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Potential distribution in an end region of the GAMMA10 tandem mirror is investigated associated with experiments for control of an electron flow to a floating endplate installed on an end wall of the vacuum vessel. The end region has an open field configuration. Mesh bias and thermal dike experiments have been carried out in order to reduce a heat flow to the endplate by suppression of secondary electron emission from the endplate. Variations of the axial potential distribution in the two experiments are studied. The observed variations agree with predictions of a theoretical potential model. This agreement shows a strong effect of the secondary electrons on the potential distribution in the end region and also indicates that the potential distribution is predominantly determined by axial particle transport. In this study, production of Yushmanov electrons is also shown.
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  • Masanori Eda, Jun–ichi Sakai, Jie Zhao, Torsten Neubert, Mitsuhi ...
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 11 Pages 3470-3476
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Using a two-dimensional electromagnetic and relativistic particle code, we show that high-frequency Langmuir waves can be generated by the plasma maser mechanism fromlow-frequency Alfvén waves excited by a temperature anisotropy.It is confirmed by the simulation that the plasma maser mechanism does not require an electron (or positron)beam component for the growth of high-frequency Langmuir waves.
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  • Sergei Bulanov, Jun–ichi Sakai
    Subject area: The physics of plasmas and electric discharges.
    1997 Volume 66 Issue 11 Pages 3477-3483
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    We investigate 3D incompressible plasma flow in thevicinities of critical points of magnetic configurations. Wepresent exact self-similar solution of the MHD equations thatcorresponds to the plasma motion with uniform deformation. Thesolution demonstrates appearance of singular distribution of theelectric current density near the magnetic field separatrixsurfaces. Within the class of the solutions, solutions have beenfound which describe formation of singularity during finiteinterval of time.
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  • Hideshi Fujishita, Susumu Katano
    Subject area: Structure of liquids and solids; crystallography.
    1997 Volume 66 Issue 11 Pages 3484-3488
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The crystal structure of antiferroelectric PbZrO3 was re-examined by high resolution powder neutron diffraction. The structure obtained with assumed modulations associated with the lattice vibrational modes Σ3(TO) and R25xy is almost the same as that obtained previously with the same assumptions. However, one coordinate of oxygen positions obtained by the refinement for all crystallographically possible parameters is different from that obtained previously under the same conditions. The difference between the two sets of the structural parameters obtained here is meaningful. The result indicates that the modulation associated with the R25xy mode is fairly distorted. This structure agrees well with that recently investigated using local-density calculations.
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  • Dal–Young Kim, Sook–Il Kwun
    Subject area: Equations of state, phase equilibria, and phase transitions.
    1997 Volume 66 Issue 11 Pages 3489-3493
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Linear birefringence behavior of [NH3C3H7]2MnCl4 was measured near normal-incommensurate phase transitions, i.e., β -γ and δ -ε transitions. Linear birefringence behaved as Δnab-- |t|0.74± 0.02 in the critical region of the two phase transitions. These results imply that two normal-incommensurate phase transitions belong to the same universality class of the 3-d XY model. In addition, linear birefringence behavior in the incommensurate γ phase is also discussed while comparing it to the previous theoretical description based on classical Landau theory.
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  • Vu Van Hung, Nguyen Thanh Hai, Nguyen Quang Bau
    Subject area: Thermal properties of condensed matter.
    1997 Volume 66 Issue 11 Pages 3494-3498
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    By the moment method established previously on the basis of the statistical mechanics, the thermodynamic properties of a strongly anharmonic face-centered and body-centered cubic crystal with point defect are considered. The thermal expansion coefficient, the specific heat Cv and Cp, the isothermal and adiabatic compressibility, etc. are calculated.
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  • Vu Van Hung, Nguyen Thanh Hai
    Subject area: Thermal properties of condensed matter.
    1997 Volume 66 Issue 11 Pages 3499-3501
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    On the basis of our previous papers (refs. \citen{rf:5} and \citen{rf:6}), the expression of melting temperature of body centered and face centered cubic crystals at non-zero pressures is derived: The present theoretical scheme is applied to Au, Ag, Al, Cu and Fe metals. In comparison with experimental data the calculated results deviate only by some percent.
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  • Tomoya Isoshima, Kazushige Machida
    Subject area: Quantum fuids and solids: liquid and solid helium.
    1997 Volume 66 Issue 11 Pages 3502-3511
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Various widely-used mean-field type theoriesfor a dilute Bose gas are critically examinedin the light of the recent discovery of Bose-Einsteincondensation of atomic gases in a confined geometry.By numerically solving the mean-field equations within the framework of the Bogoliubov approximation both stationary non-uniform case and the vortex case under rotation in a cylindrically symmetric vessel are investigated.We obtain spatial structures of condensate, non-condensate, anomalous correlation.The low lying excitation spectra, the local density of statesand the circulating current density in a vortexcorresponding to various levels of mean-field theories are predicted.
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  • Satoshi Toyofuku, Takashi Odagaki
    Subject area: Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties).
    1997 Volume 66 Issue 11 Pages 3512-3516
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Percolation process is studied in a model granular systemon a square lattice, where grains are grown around seeds up tothe n-th neighbors. Critical percolation coverage is shown tooscillate as a function of n. The coverage at which the numberof particles on the surface of clusterstakes a maximum is also shown to oscillateas a function of n. These oscillations are due to the projections ofgrains. The percolation process is shown to belong to the universalityclass of two dimensional percolation.
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  • Izumi Hase, Yoshikazu Nishihara
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3517-3521
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The electronic energy band structure for Sr3Ru2O7, which is related to the superconducting Sr2RuO4 and whose structure is called double-layered structure, has been calculated by using the scalar-relativistic full-potential linearized augmented plane wave (FLAPW) method within the local-density approximation in the paramagnetic case. The result of the calculation suggests that this compound is a metal and its electronic structure looks like that of Sr2RuO4. However, we found one of the Fermi surfaces has a large dispersion along kz axis. The calculated large density of states at the Fermi energy indicates that Sr3Ru2O7 may have a ferromagnetic ground state.
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  • Hideo Hasegawa
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3522-3527
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    A systematic study has been made on the metal-insulator (MI) transition of the doubly degenerate Hubbard model (DHM)in the paramagnetic ground state, by using the slave-boson mean-field theory which is equivalent to the Gutzwiller approximation (GA). For the case of infinite electron-electron interactions, we obtain the analytic solution, which becomes exact in the limit of infinite spatial dimension. On the contrary, the finite-interaction case is investigated by numerical methods using the simple-cubic model with the nearest-neighbor hopping. The mass-enhancement factor, Z, is shown to increase divergently as one approaches the integer fillings (N = 1, 2, 3), at which the MI transition takes place, N being the total number of electrons.The calculated N dependence of Z is compared withthe observed specific-heat coefficient, γ, of Sr1-xLaxTiO_3 which is reported to significantly increase as x approaches unity.
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  • Atsushi Tsuruta, Yoshiaki Ono, Tamifusa Matsuura, Yoshihiro Kuroda
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3528-3535
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    As a straightforward extention of the study on infrared divergences in pseudo-particle spectra in the single-channel degenerate impurity Anderson model, those of the multichannel model are examined with use of the expansion from the large limit of the spin-orbital degeneracy N. Analysis with the most divergent terms in the expansion shows that exponents of spectra of the slave boson and the pseudo-fermion in the M-channel model with 1 ≤ M << N are given respectively by 1-n_f2M/N and (2n_f-n_f2)M/N, where n_f is the average number of localized electrons at the impurity site. When M=1, the results recover those obtained earlier in the single channel model. In the limits, n_f → 1 and M-2 << 1, these results tend to those obtained by the non-crossing approximation (NCA) study. It also shows that the scattering rate of the conduction electrons in the M-channel model includes infrared divergent terms proportional to (1-n_f)(1-M-2) in contrast to the absence of infrared divergent terms in the single-channel model.
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  • Kenji Suzuki, Yoshiyuki Ono
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3536-3542
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The magnetization due to the orbital motion of electrons in confinedtwo dimensional disordered systems subject to perpendicular strong magneticfields is investigated numerically.The effects of the edge states and randomness are discussedfrom the view point of microscopic current distribution. The magnetization as a function of the filling factor is modifiedfrom that for the impurity free case by the fluctuationsin the bulk region, which are of the order of the effective Bohr magneton. On the other hand, the contributions of the edge statesto the magnetization and to the current distributionare stable against the randomness.
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  • Ming–Fa Lin, Kenneth Wen–Kai Shung
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3543-3550
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The self-energy of an electron gas confined to a cylindrical tubule is studied within the dynamic random phase approximation. As a result of the cylindrical symmetry, each subband is described by the angular momentum (l), and the excitation spectrum by the transferred angular momentum (L) of the Coulomb interactions. All of the intrasubband (L=0) and intersubband (L≠ 0) interactions are included in the self-energy. Quasiparticle energy and energy width exhibit the multiple divergent structures, mainly owing to the various plasmons. The contributions due to the ± L intersubband plasmons are the same for the l=0 subband, but not the same for the l≠ 0 subbands. Hence, there are more divergent structures in the self-energies of the l≠ 0 subbands. The downshift of subband edge strongly depends on the carrier density, the tubular radius, and the effective mass. It exhibits cusps or jumps at certain carrier densities, where the subband crossings occur. The special jumps are related to a new L=0 plasmon.
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  • Youichi Yanase, Kosaku Yamada
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3551-3557
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    In the d-electron and f-electron systems, generally, electrons tend to localize at their atomic sites. In these systems, if an atom has plural localized electrons, Hund's rule coupling in the atom is important for the property of the system. We investigate the effect of Hund's rule coupling on the Kondo problem with plural localized electrons by using scaling theory. Following the Poorman's scaling, we give the scaling equations which describethe Kondo effect with Hund's rule coupling. It is shown that the strong coupling fixed point of s-d exchange interaction isnot changed by the Hund's rule coupling. The characteristic energy TK (Kondo temperature) decreases smoothly with increasing Hund's rule coupling.Even if the hybridization terms between conduction electrons and localized orbitals are anisotropic by a crystal field, the characteristic energy is unique, except for the case Hund's rule coupling JH = ∞. There exist ferromagnetic couplings between the localized electron and conduction electrons in the different orbital symmetry. However, they and Hund's rule coupling itself are irrelevant operators.Therefore, the singlet ground state is stable against the Hund's rule coupling.
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  • Tsuneya Ando, Takuji Seri
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3558-3565
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The conductance of single-shell carbon nanotubes is numerically calculated in the effective-mass approximation by treating scattering from impurities exactly.The magnetic-field dependence of the conductance depends sensitively on the mean free path.When the mean free path is sufficiently large, undoped metallic nanotubes exhibit a large positive magnetoresistance in agreement with the prediction of the Boltzmann transport equation.This positive magnetoresistance disappears when the mean free path becomes comparable to the circumference length.
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  • Shigemasa Suga, Hideyuki Harada, Hideki Matsubara, Yuji Saitoh, Akio K ...
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3566-3569
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The lineshapes of core photoemission spectra of U3P4 and U3As4 single crystals are studied. It is found that the U derived core states show characteristic asymmetry except for the oxidized surface, whereas the asymmetry is negligible for the anion derived core states. These results are discussed by considering the screening effect by the U 6d state and hybridization effects. The constant final state spectra in the U 5d→ 5f absorption region is also discussed.
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  • Takao Mori, Kyohei Ogawa, Ken–ichi Yoshida, Kenjiro Miyano, Yasu ...
    Subject area: Electron states in condensed matter.
    1997 Volume 66 Issue 11 Pages 3570-3576
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Temporal and spatial properties were investigated forthe recently discovered photoinduced insulator to metal transition in Pr0.7Ca0.3MnO3.Time evolution of the photocurrent upon irradiation with a laser pulse and its laser-power and applied-voltage dependence were measured and analyzed. Irradiation patterns were controlled and sample length and width were varied. Two components of the photocurrent were separated. The slow component which was concluded to be critical for the transition, was suggested to originate from small metallic “islands” being created within the electrode gap by the irradiation. Measurements done on samples with the controlled width gave proof of the shrinking of the conduction path with decreasing current, supporting the picture of the conduction path being under stress from the surrounding charge ordered, antiferromagnetic bulk and being sustained by the current. Lack of dependence of the resistance on the sample length was observed, indicating that the major contribution to the voltage drop is determined by some “neck” in the conduction path.
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  • Hideaki Maebashi, Hidetoshi Fukuyama
    Subject area: Electronic transport in condensed matter.
    1997 Volume 66 Issue 11 Pages 3577-3590
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Electrical conductivity σ (ω, T)of a lattice electron system due only to mutual Coulomb interaction is studied on the basis of the Fermi liquid theory, ω and T being the external frequency and the temperature, respectively. Based on the Kubo formula to respect the consistency between the selfenergyand the vertex corrections, a formulation of σ (ω, T)is given in terms of memory function which is extended to the matrix form.In this formulation, it is explicitly demonstrated that, in the absence of Umklapp processes, T2-term in the resistivity vanishesas it should in spite of the fact that the total current is not conserved.
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  • Hiroshi Shimahara, Dierk Rainer
    Subject area: Superconductivity.
    1997 Volume 66 Issue 11 Pages 3591-3599
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    The effects of a tilted magnetic field on two-dimensional type-II superconductors of s- and d-wave pairing are studied. This includes a study of the crossover from vortex states to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state when the direction of the magnetic field is changed from perpendicular to the conducting plane to a parallel orientation. The FFLO state is obtained in the limit of a parallel magnetic field, and vortex phases with a large quantum number n>0 (a higher Landau level) appear for tilted magnetic fields. At fixed tilt angle, the critical field exhibits a characteristic gtemperature dependence due to the change of the discrete quantum number. The relevance of the results for the observation and the identification of the FFLO state in the organic and Tc superconductors is discussed.
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  • Yoshihisa Obi, Manabu Ikebe, Hiroyasu Fujimori
    Subject area: Superconductivity.
    1997 Volume 66 Issue 11 Pages 3600-3604
    Published: November 01, 1997
    Released on J-STAGE: October 01, 1999
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    Anomalous behavior of Tc of the superconductor/superconductor multilayer system, NbTi/Nb was quantitatively analyzed applying an advanced approximation for the proximity effect. The observed minimum of Tc as a function of the structure wavelength λ was suggested to come from the combined effects of Tc degradation of the Nb sublayer and interdiffusion of Nb and Ti atoms through the boundary.
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