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Agung Budiyono, Katsuhiro Nakamura
2003 Volume 72 Issue 7 Pages
1595-1598
Published: July 15, 2003
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Assuming that the quantum point contacts (QPCs) connecting the cavity to large reservoirs of source and drain have a transversal profile of harmonic potential that accommodates an extremely narrow Gaussian wave packet as the ground state, we deduce that quantum correction to the lowest mode transmission coefficient can be approximated as a summation over periodic orbits that are well coupled to both the entrance and exit openings. Energy averaging around the Fermi energy gives the damping factor so that only a few shortest periodic orbits contribute to conductance fluctuations. This confirms the experimental and self-consistent numerical results observed recently in quantum dots, that conductance fluctuations are dominated by a few discrete frequencies.
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Kazue Kudo, Tetsuo Deguchi
2003 Volume 72 Issue 7 Pages
1599-1602
Published: July 15, 2003
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Branches such as bifurcations or multiple branches are observed in the flow of eigenvalues for the inhomogeneous transfer matrix of the XXZ spin chain. The spectral flow for the XXZ anisotropic parameter Δ is obtained by directly diagonalizing the transfer matrix in the regime: −1≤Δ≤1, where the inhomogeneous transfer matrix is real and symmetric. The branches are considered as novel spectral behaviors, which are not decomposed into simple superpositions of level crossings. We may call them
level bifurcations. We also observe that no branches appear in the homogeneous case. The appearance of some of the branches are confirmed through the Bethe ansatz method.
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Yukinobu Kawakita, Shinya Hosokawa, Takeshi Enosaki, Koji Ohshima, Shi ...
2003 Volume 72 Issue 7 Pages
1603-1606
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The dynamic structure factor
S(
Q,ω) of liquid (
l-) Mg was measured at 700°C using high-resolution inelastic X-ray scattering. Based on the high-quality experimental data presented in this paper, we discuss the particle dynamics in dense
l-Mg using the generalized hydrodynamic theory for phonon excitations. The particle motion in this liquid is influenced by collective longitudinal modes, similar to other simple liquid metals such as
l-alkali metals. The
Q dependence of quasielastic line width can be interpreted based on an existing theory modified from the
de Gennes formalism.
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Ivan A. Sergienko, Stephanie H. Curnoe
2003 Volume 72 Issue 7 Pages
1607-1610
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It is shown that both structural phase transitions in Cd
2Re
2O
7, which occur at
Ts1=200 K and
Ts2=120 K, are due to an instability of the Re tetrahedral network with respect to the same doubly degenerate long-wavelength phonon mode. The primary structural order parameter transforms according to the irreducible representation
Eu of the point group
Oh. We argue that the transition at
Ts1 may be of the second order, in accordance with experimental data. We obtain the phase diagram in the space of phenomenological parameters and propose a thermodynamic path that Cd
2Re
2O
7 follows upon cooling. Couplings of the itinerant electronic system and localized spin states in pyrochlores and spinels to atomic displacements are discussed.
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Hiroaki Koga, Yoshimichi Nakamura, Satoshi Watanabe
2003 Volume 72 Issue 7 Pages
1611-1614
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Repulsion-induced order formation is shown to be crucial to the occurrence of the transition from rhombohedral boron nitride (rBN) to cubic boron nitride (cBN), by performing molecular dynamics simulations. Due to the repulsion among B (N), a face-centered-cubic (fcc) lattice of B (N) is formed under compression. This restores the stacking sequence of basal planes, which is disordered during the compression. The fcc lattice directly becomes the fcc lattice of cBN. These results imply the possibility of controlling the transition by controlling the repulsion.
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XiaoJun Liu, Yutaka Moritomo, Tohru Kawamoto, Akio Nakamoto, Norimichi ...
2003 Volume 72 Issue 7 Pages
1615-1618
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Density
nHS of photoexcited high-spin (HS) sites in a spin–crossover film (Nafion-[Fe(Htrz)
3]; Htrz = 1,2,4-4H-triazole) was systematically investigated against temperature
T and excitation power density
P. At low temperatures (≤35 K), the
nHS–
P curve shows a nonlinear increase when
P reaches a critical value (
Pc). We interpreted the increase in terms of the
dynamical phase transition into the condensed state of photoexcited HS molecules, and derived the
P–
T phase diagram. The
P–
T phase diagram and the
nHS–
P curves were analyzed with an Ising-like model which includes a temperature-dependent field.
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Takashi Yanagisawa, Hajime Shibata
2003 Volume 72 Issue 7 Pages
1619-1622
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We show that a two-band model with
k-dependent superconducting gaps well describes the transmission and optical conductivity measured for MgB
2 thin films. It is also shown that the two-band anisotropic model consistently describes the specific-heat jump and thermodynamic critical magnetic field
Hc. A single-gap anisotropic model is shown to be insufficient to understand consistently optical and thermodynamic behaviors. In our model, the pairing symmetry in each band has an anisotropic characteristic which is determined almost uniquely; the superconducting gap in the σ-band has anisotropy in the
ab-plane and the gap in the π-band has a prolate form exhibiting anisotropy in the
c-direction.
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Masashige Matsumoto, Cyril Belardinelli, Manfred Sigrist
2003 Volume 72 Issue 7 Pages
1623-1626
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The inhomogeneous 3 Kelvin phase is most likely a superconducting state nucleating at the interface between micrometer-sized Ru-metal inclusions and Sr
2RuO
4 above the bulk onset of superconductivity. This filamentary superconducting state yields a characteristic temperature dependence of the upper critical field which is sublinear, i.e.,
Hc2(
T)∝(
T*−
T)
γ with 0.5≤γ<1 (
T*: nucleation temperature). The Ginzburg–Landau theory is used to analyze the behavior of the nucleated spin–triplet phase in a field and the characteristic features of
Hc2 observed in the experiment are explained based on a two-component order parameter in the presence of a filament of enhanced superconductivity with a finite width.
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Masafumi Ito, Yukio Yasui, Satoshi Iikubo, Minoru Soda, Masatoshi Sato ...
2003 Volume 72 Issue 7 Pages
1627-1630
Published: July 15, 2003
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The wave vector (
q)- and energy (ω)-dependent magnetic excitation spectra χ″(
q,ω), have been studied in the temperature (
T) range of 10K≤
T<150 K on single crystals of La
1.48Nd
0.4Sr
0.12CuO
4, which has the static “stripe” order in the low-temperature phase. The incommensurability δ of the peak of χ″(
q,ω) found by the
q-scans and the peak width Δ
q exhibit characteristic
T dependences. The observed profiles show a clear incommensurate structure even at rather high temperatures. The results indicate that effects of the slowly fluctuating “stripes” exist not only in the low-temperature tetragonal (LTT) phase but also in the orthorhombic phase (LTO1) of the present system.
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Yoshiharu Kanegae, Yoji Ohashi
2003 Volume 72 Issue 7 Pages
1631-1634
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We investigate the nuclear spin–lattice relaxation rate (
T1T)
−1 in atomic-scale superconductor/magnet multilayered systems and discuss the discrepancy between two recent (
T1T)
−1 experiments on Ru in RuSr
2YCu
2O
8. When the magnetic layers are in the antiferromagnetic state, (
T1T)
−1 in the magnetic layers is shown to decrease with decreasing temperature due to the excitation gap associated with the magnetic ordering. The proximity effect of superconductivity on (
T1T)
−1 in the magnetic layer is negligibly small. Our result indicates that the temperature dependence of (
T1T)
−1 on Ru in RuSr
2YCu
2O
8 likely originates from the antiferromagnetism in the RuO
2 layers, but not from the superconductivity in the CuO
2 layers.
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Kanako Tooriyama, Tatsuya Uezu
2003 Volume 72 Issue 7 Pages
1635-1644
Published: July 15, 2003
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We study supervised learning by Ising perceptrons for a class of non-monotonic teacher input–output relations employing the replica method with the Gibbs algorithm. We consider up to one-step replica symmetry breaking (1RSB) solutions. We find that the behaviour of the learning curve depends on the shape of the teacher input–output relation. In particular, for the class of teacher input–output relations, which represents an extension of the reversed-wedge problem, a peculiar type of learning, perfect anti-learning (PAL), exists, whereas perfect learning (PL) does not exist. Further, we find that the students’ vectors cannot tend to the teacher vector, that is, the students cannot learn the teacher completely. The theoretical results are confirmed by the results of Monte Carlo simulations.
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Yoshiyuki Kabashima
2003 Volume 72 Issue 7 Pages
1645-1649
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We investigate dynamics of an inference algorithm termed the belief propagation (BP) when employed in spin glass (SG) models and show that its macroscopic behaviors can be traced by recursive updates of certain auxiliary field distributions the stationary state of which reproduces the replica symmetric solution offered by the equilibrium analysis. We further provide a compact expression for instability condition of the BP’s fixed point which turns out to be identical to that of instability for breaking the replica symmetry in equilibrium when the number of couplings per spin is infinite. This correspondence is extended to the case of finite connectivity to determine the phase diagram, which is numerically validated.
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Nobuyuki Nakamura, Tetsuro Nakahara, Shunsuke Ohtani
2003 Volume 72 Issue 7 Pages
1650-1654
Published: July 15, 2003
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The 1
s Lamb shift in hydrogenlike rhodium has been measured by observing radiative recombination into the 1
s vacancy of bare rhodium produced and trapped in the Tokyo electron beam ion trap. The 1
s binding energy was determined by measuring the radiative recombination X-ray energy and subtracting the electron beam energy from it. The electron beam energy was measured by simultaneously observing radiative recombination into the 1
s vacancy of bare krypton, for which the level energy is precisely known from an existing experiment. The 1
s Lamb shift in hydrogenlike rhodium has been found to be 28.7±3.4 eV. At the same time, the two electron contribution to the ground state energy of heliumlike rhodium and krypton have been determined. Experimental results are compared with existing theories.
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Hiroto Kuninaka, Hisao Hayakawa
2003 Volume 72 Issue 7 Pages
1655-1663
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The oblique collision between an elastic disk and an elastic wall is numerically studied. We investigate the dependency of the tangential coefficient of restitution on the incident angle of impact. From the results of simulation, our model reproduces experimental results and can be explained by a phenomenological theory of the oblique impact.
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Takahiro Kawashima, Seiji Miyahara, Yukiharu Ohsawa
2003 Volume 72 Issue 7 Pages
1664-1669
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Nonstationary shock waves in a magnetized plasma are studied with theory and particle simulations. In a strong shock wave, the amplitude oscillation occurs. This arises from the ion reflection. The oscillation period is ∼0.3 times the ion gyroperiod, which is equal to the time in which reflected ions return to the shock wave. In the oscillation, the magnetic field is strong when the potential is small, and vice versa. At the phase of strong magnetic field, the field profiles are sharp. The field values predicted by the theory for stationary shock waves agree with simulation results obtained when the wave profiles are sharp.
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Dilip Kumar Saha, Toetsu Shishido, Hiroshi Iwasaki, Ken-ichi Ohshima
2003 Volume 72 Issue 7 Pages
1670-1674
Published: July 15, 2003
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X-ray diffraction study was performed for the atomic arrangements in Pt-rich (87.5 at.%) Cu–Pt alloy with the cubic structure both in the disordered and ordered states using single crystal samples. In the disordered state obtained by quenching from temperatures above 800°C, short-range order (SRO) diffuse scattering intensity maxima were observed at X-point (100, 110 and their equivalent positions) and at L-point (1/2 1/2 1/2 and its equivalent positions). The appearance of the two kinds of intensity maxima is as previously observed in alloys with less Pt concentration, but the intensity ratio of the two maxima is different. The Warren–Cowley SRO parameters, α
lmn, were determined from the observed SRO diffuse scattering intensities and a significant lower value has been found for α
200. The short-range ordered structure is interpreted as being formed as a result of competition between the X-point ordering tendency and the L-point ordering tendency in the alloy. At temperatures lower than 430°C, an ordered structure forms with superlattice reflections both at the X- and L-points. Inspection of the intensities of the reflections shows that the structure is cubic and of the Tang’s type [Acta Crystallogr.
4 (1951) 377], which is expressed as the ABC
6-type structure. This, together with our previous finding in Pt-rich Pt–Mn alloys [Takahashi
et al.: J. Phys. Soc. Jpn.
71 (2002) 681], is the first experimental confirmation of the presence of long-range ordered state in the alloy with such a low solute concentration as 12.5 at.% and this ordering behavior is characteristic of Pt-based alloys.
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Yoshihiro Ishibashi, Makoto Iwata
2003 Volume 72 Issue 7 Pages
1675-1681
Published: July 15, 2003
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The phase diagram and elastic stiffness constants in Martensite alloys with the symmetry change from the cubic m\\bar3m to the tetragonal 4/mmm and the orthorhombic mmm symmetries are discussed on the basis of the Landau-type free energy function expressed in terms of the strain components,
u1,
u2 and
u3. It was found that some of elastic stiffness constants corresponding to the shear deformation become extremely small not only in the vicinity of the transition temperature but also near the morphotropic phase boundary where the Landau-type free energy function is isotropic or less anisotropic in the order parameter space.
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Mamoru Yamashita
2003 Volume 72 Issue 7 Pages
1682-1688
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A global phase diagram of Maier–Saupe model for nematic–isotropic phase transition on the external field versus temperature plane is obtained, where due to non-polar property of the system two sets of order parameters and the conjugate fields are required to describe completely the phenomena. The phase diagram is argued in the context of a similarity of the model to the three-state Potts model. Inhomogeneity at the thin system sandwiched by parallel walls is expressed in terms of an effective external field, where effects due to homeotropic, homogeneous, planer and oblique anchoring walls are classified systematically. A shift of the transition temperature together with the property of phase transition is explained systematically on the basis of the phase diagram of bulk system, where the changes of the order of phase transition is related to a critical point and a tricritical one appearing in the phase diagram.
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Ezat Keshavarzi, Abbas Ali Rostami, Farzane Tabarinia
2003 Volume 72 Issue 7 Pages
1689-1697
Published: July 15, 2003
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In a recent article, we have presented a hard-like equation of state, HLEOS, based on the hard-like behavior of fluids at high densities. It has been shown that the hard-like behavior of any real fluid starts at the common bulk modulus point for each isotherm. To confirm our claim, we have shown that the structure factor of real fluids for such conditions may be predicted just using the Percus–Yevick equation for hard fluids. We have introduced and presented an analytical expression for effective pair correlation function at contact,
geff(σ), for real fluids that it shows a new corresponding states. The HLEOS predicts thermodynamic properties of all kind of fluids, including non-polar, polar, and hydrogen-bonded systems such as Ar, Xe, CH
4, DMB, N
2, C
2H
4, CO, C
2H
5OH, and H
2O successfully. The hard-like EOS has two temperature-dependent parameters, which are related to the soft and hardness of the repulsive branch of the potential. This EOS is also able to predict some known regularities for fluids such as the common bulk modulus point, and common compression point. We have used the HLEOS in prediction of the sound velocity and density for fluids and compared it with the other equations of state.
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Hideaki Sakai, Hidekatsu Suzuura, Tsuneya Ando
2003 Volume 72 Issue 7 Pages
1698-1705
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The band gap, the single-particle energy, and the effective mass are calculated for semiconducting carbon nanotubes in a random-phase approximation within a
k·
p scheme. The energy gaps are shown to be strongly enhanced due to the Coulomb interaction, while effects on the effective mass along the axis direction are small. For realistic values of the interaction parameter, effects of the dynamical screening are sufficiently weak, and the conventional screened Hartree–Fock approximation is shown to work quite well. Further, the band gap contains a term with a residual logarithmic dependence on the tube diameter
d after being scaled by 1⁄
d.
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Toshihiro Kubo, Arisato Kawabata
2003 Volume 72 Issue 7 Pages
1706-1717
Published: July 15, 2003
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We investigate effects of electron–electron interaction on the transmission probability of electrons through a tunnel junction in a strong magnetic field. We start with the Hartree–Fock approximation, and we show that the coulomb interaction, which gives rise to the divergence of Fock correction, should be replaced by the dynamically screened interaction. We also show that we should use the bare coulomb interaction for Hartree term. We take into account higher order contributions using a simple renormalization group approach. The temperature dependence of the transmission probability is qualitatively similar to that of a one-dimensional system.
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Naoki Kitaura, Hiroyoshi Itoh, Yasuhiro Asano, Yukio Tanaka, Jun-ichir ...
2003 Volume 72 Issue 7 Pages
1718-1723
Published: July 15, 2003
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Effects of impurity scattering on tunneling conductance in dirty normal-metal/insulator/superconductor junctions are studied based on the Kubo formula and the recursive Green function method. The zero-bias conductance peak (ZBCP) is a consequence of the unconventional pairing symmetry in superconductors. The impurity scattering in normal metals suppresses the amplitude of the ZBCP. The degree of the suppression agrees well with results of the quasiclassical Green function theory. When superconductors have
d+
is-wave pairing symmetry, the time-reversal symmetry is broken in superconductors and the ZBCP splits into two peaks. The random impurity scattering reduces the height of the two splitting peaks. The position of the splitting peaks, however, almost remains unchanged even in the presence of the strong impurity scattering. Thus the two splitting peaks never merge into a single ZBCP.
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Akihiko Kawano, Yukiko Mizuta, Hiroyuki Takagiwa, Takahiro Muranaka, J ...
2003 Volume 72 Issue 7 Pages
1724-1728
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We present here the low temperature electrical transport and magnetic properties of intermetallic rhenium boride compounds. We newly discovered the superconductivity of Re
7B
3 (
Tc=3.3 K) and its superconducting properties were discussed. We also discussed the physical properties of Re
3B (
Tc=4.8 K), of which supreconductivity was discussed by Strukova
et al. The crystal structures of these compounds (Re
3B and Re
7B
3) are orthorhombic (space group
Cmcm) and hexagonal (
P6
3⁄
mc), respectively, and have differnt B–B bonds each other. The magnetization (
M–
H) curves of these compounds show a typical type-II superconducting behavior. The lower critical field,
Hc1(0), the upper critical field,
Hc2(0) and the Ginzburg–Landau (GL) parameter, κ are, 8 mT, 5.2 T and 35 for Re
3B and 6 mT, 0.9 T and 17 for Re
7B
3.
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Minoru Soda, Yukio Yasui, Toshiaki Fujita, Takeshi Miyashita, Masatosh ...
2003 Volume 72 Issue 7 Pages
1729-1734
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Neutron diffraction studies have been carried out on a single crystal of oxygen-deficient perovskite TbBaCo
2O
5.5 in the temperature range of 7–370 K. There have been observed several magnetic or structural transitions. Among these, the existence of the transitions to the insulating phase from the metallic one at ∼340 K, to the one with the ferromagnetic moment at ∼280 K and possibly to the antiferromagnetic one at ∼260 K, with decreasing temperature
T correspond to those reported in former works. We have studied the magnetic structures at 270 K and 250 K and found that all Co
3+ ions of the CoO
6 octahedra are in the low spin state and those of the CoO
5 pyramids carry spins which are possibly in the intermediate spin state. Non-collinear magnetic structures are proposed at these temperatures. Two other transitions have also been observed at the temperatures, ∼100 K and ∼250 K.
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Masafumi Tamura, Yuko Hosokoshi, Daisuke Shiomi, Minoru Kinoshita, Yas ...
2003 Volume 72 Issue 7 Pages
1735-1744
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We have investigated the crystal structures and magnetic properties of the α- and δ-phases of an organic radical
p-NPNN (
p-nitrophenyl α-nitronyl nitroxide), which yielded the first organic bulk ferromagnet, β-
p-NPNN (the β-phase). The results are compared with those of the β- and γ-phases, which show distinct magnetic ordering due to intermolecular ferromagnetic couplings. Common structural features are found in the four phases. Unlike the other phases, the α-phase exhibits a weak antiferromagnetic interaction. This is attributable to phenyl–phenyl overlapping found only in the α-phase. The crystal structure of δ-
p-NPNN contains a packing motif similar to that of the γ-phase. Though the δ-phase exhibits ferromagnetic interactions, it shows no magnetic ordering down to 0.46 K. It is suggested that ferromagnetic two-leg spin ladders are formed in the δ-phase, instead of a two-dimensional network as in γ-
p-NPNN. This low dimensionality explains the absence of a magnetic transition.
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Yuji Muro, Kyoutaro Yamane, Moo-Sung Kim, Toshiro Takabatake, Claude G ...
2003 Volume 72 Issue 7 Pages
1745-1750
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We have studied the valence states and thermoelectric properties of Yb
2T
3Sn
5 (T = Pt and Pd) with two inequivalent Yb sites. For Yb
2Pt
3Sn
5, the 4
f-hole occupation number
nf is estimated to be 0.4 at 300 K from the magnetic susceptibility and
LIII-edge absorption spectrum. Intermediate-valence behaviors manifest themselves in a largely negative value of the paramagnetic Curie temperature, −216 K, a broad peak at 300 K in the magnetic part of the resistivity, and a large minimum in the thermopower, −38 μV/K at 60 K. The specific heat shows no transition down to 0.6 K. These results are explained by a model in which Yb ions in one site are divalent and those in the other site are in a valence fluctuating state with a Kondo temperature of 200 K. Thus, Yb
2Pt
3Sn
5 is a rare example of the heterogeneous mixed-valence system. An isostructural compound Yb
2Pd
3Sn
5 has a larger unit-cell volume by 2.4%, which allows the Yb ions in both the sites to be divalent.
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Kenji Watanabe, Yoshiya Uwatoko, Yoshikazu Tabata, Hiroaki Kadowaki, C ...
2003 Volume 72 Issue 7 Pages
1751-1757
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Neutron diffraction experiments have been carried out to study the nature of the magnetic order of the pseudo-binary alloy system Ce(Ru
0.90Rh
0.10)
2(Si
1−yGe
y)
2. Response of the ordered atomic magnetic moment, μ, the transition temperature,
TN, and the magnitude of the magnetic modulation vector,
q, to the chemical pressure and also to the applied hydrostatic pressure,
P, were examined at low temperatures. When
y changes, all of μ,
TN and
q show a sudden alteration of the manner of the
y-dependence at around
y∼0.08. The
P-dependence of
q shows quite different features for different
y’s of 0.0, 0.2 and 0.25. On the basis of these observations the possibility of a pressure-induced alternation of the magnetic regime of the order is discussed.
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Takashi Naka, Jie Tang, Jinhua Ye, Akiyuki Matsushita, Takehiko Matsum ...
2003 Volume 72 Issue 7 Pages
1758-1762
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We report the pressure effects on lattice constants, magnetic susceptibility, specific heat and electrical resistivity in the orthorhombic PrCu
2. Anisotropic compression is realized to be κ
a≈κ
c<κ
b even under hydrostatic pressure. Above 1.2 GPa, susceptibility shows a remarkable maximum at
Tmax. This fact implies that the pressure-induced magnetic ordering occurs above 1.2 GPa. Also the results of specific heat and electrical resistivity reveal the anomaly at
P=1.2 GPa to be due to an antiferromagnetic ordering. The temperature–pressure phase diagram is presented up to 2 GPa.
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Makoto Yoshida, Keiichi Koyama, Makoto Shirakawa, Akira Ochiai, Kazuo ...
2003 Volume 72 Issue 7 Pages
1763-1767
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Cyclotron resonance (CR) and magnetic resonance measurements on single crystals of GdSb have been performed at temperatures between 1.4 K and 30 K in the frequency range from 50 to 110 GHz. By using a high-quality crystal with the residual resistivity ratio of about 500, two CR absorption lines are observed at low temperatures for
B||[001] in addition to an antiferromagnetic resonance. The effective mass values are estimated to be 0.26
m0 and 0.50
m0, respectively, which are reasonably consistent with the results of dHvA measurements. On the other hand, in the case of a low grade crystal, a magnetic resonance of Gd impurities is observed. The absorption line of the impurities shows broadening and
g-shift at low temperatures.
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Hideki Yamagata, Hiroyuki Miyamoto, Koichi Nakamura, Masahiro Matsumur ...
2003 Volume 72 Issue 7 Pages
1768-1773
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We studied Zn-substitution effect on the high-
Tc superconductors, underdoped La
2−xSr
xCu
1−yZn
yO
4 (
x=0.10;
y=0, 0.01, 0.02), optimally doped (
x=0.15;
y=0, 0.02), and overdoped (
x=0.20;
y=0, 0.03, 0.06) in a temperature range of
T=4.2–300 K, using Cu nuclear quadrupole resonance (NQR) spin–echo technique. We found full disappearance of the Cu NQR signals for the Zn-substituted, Sr-underdoped
x=0.10 samples below about 40 K, partial disappearance for the Sr-optimally doped ones below about 50 K, but not for the overdoped
x=0.20 ones. From the Zn-doping, the Sr-doping and the temperature dependence of the wipeout effect, we associate the wipeout effect with Zn-induced Curie magnetism or its extended glassy charge–spin stripe formation.
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Ae Ran Lim, Ji Won Kim, Choon Sup Yoon
2003 Volume 72 Issue 7 Pages
1774-1778
Published: July 15, 2003
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The rotation patterns of the nuclear magnetic resonance of
11B (
I=3⁄2) in a nonlinear optical CsLiB
6O
10 single crystal were measured in three mutually perpendicular crystal planes. We observed sixteen different spectra which could be divided into two groups corresponding to two kinds of boron atoms, B(1) and B(2), having different boron–oxygen rings and lying at crystallographically inequivalent sites. From these results, the quadrupole coupling constants and the asymmetry parameters were determined at room temperature for the first time. For the 4-coordinated B(1),
e2qQ⁄
h=0.23±0.03 MHz and η=0.456±0.004, and for the 3-coordinated B(2),
e2qQ⁄
h=2.58±0.03 MHz and η=0.276±0.004. The directions of the principal axes of the electric field gradient tensors were also determined. The spectra for the two groups have different principal values of the electric field gradient tensor and originate from magnetically inequivalent sites. The principal
Z-axis of the EFG tensor nearly coincides with the normal to the plane of the boron–oxygen triangle. We found an interesting correlation between the asymmetry parameter and the largest nonlinear optical coefficient.
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Van An Dinh, Motohiko Saitoh
2003 Volume 72 Issue 7 Pages
1779-1783
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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The cyclotron resonance absorption of two-dimensional electrons in semiconductor heterostructures in high magnetic fields is investigated. It is assumed that the ionized impurity potential is a dominant scattering mechanism, and the theory explicitly takes the Coulomb correlation effect into account through the Wigner phonons. The cyclotron resonance linewidth is in quantitative agreement with the experiment in the Wigner crystal regime at
T=4.2 K. Similar to the cyclotron resonance theory of the charge density waves pinned by short-range impurities, the present results for the long-range scattering also show the doubling of the resonance peaks. However, unlike the case of the charge density waves, our theory gives the pinning mode independent of the bulk compressibility of the substrate materials.
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Hasanudin, Noritaka Kuroda, Tomoko Kagayama, Toyonari Sugimoto, Michi ...
2003 Volume 72 Issue 7 Pages
1784-1788
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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Pressure dependence of the charge distribution along the columns of tetracyanoquinodimethane (TCNQ) molecules in Cs
2TCNQ
3, which is a semiconducting 1/3-filled Hubbard system with the optical energy gap of 0.3 eV at ambient conditions, has been studied by the infrared and visible absorption experiments. An electronic phase transition is found to occur at around 3.6 GPa, in accordance with the previously reported insulator-to-metal transition. Our result suggests that this phase transition accompanies a symmetry change in the relative position of the TCNQ
− radical molecules sandwiching the TCNQ
0 neutral molecule. In addition, the π
∗ electrons, which are localized on the TCNQ
− molecules in the low-pressure phase, are delocalized significantly in the high-pressure phase. However, in the high-pressure phase the π
∗ electrons still maintain the localizing character. The charge-transfer degree of the neutral-like and radical-like molecules of the high-pressure phase is estimated to be ρ=0.46–0.50 and 0.75–0.77, respectively.
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Shin-ichi Kondo, Mitsugu Kakuchi, Atsushi Masaki, Tadaaki Saito
2003 Volume 72 Issue 7 Pages
1789-1791
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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The luminescence properties of CsPbBr
3 films prepared via the amorphous phase by crystallization are dominated by free-exciton emission, and only a weak trace of emission due to trapped excitons was observed, in contrast to the case of bulk CsPbBr
3 crystals. In particular, the films in the microcrystalline state show by more than an order of magnitude stronger free-exciton emission than in the polycrystalline state. The enhanced free-exciton emission is suggestive of excitonic superradiance.
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Krishna G. Nath, Yüksel Ufuktepe, Shin-ichi Kimura, Yuichi Haruya ...
2003 Volume 72 Issue 7 Pages
1792-1799
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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Systematic results of the photoemission spectra for different core levels such as, Tm 4
p, 5
p and 3
d in the mixed valent Tm-monochalcogenides (TmS, TmSe and TmTe) obtained by both experimentally and theoretically are reported. The effects of the electron–electron correlation due to the interaction between core-holes and 4
f-electrons or the interaction between different configurations are considered to explain the spectral features, depending on the principal (
n) and orbital quantum numbers of the core levels. Any sharp peak corresponding to a spin–orbital term is not observed especially from the
n=4 states. Instead, the multiplet structures are dominantly observed, and the physical identity of the spin–orbital peaks is totally or partially dissolved into the multiplets. Moreover, the electron-correlation effect is found to be dependent on the valence components (Tm
2+ and Tm
3+). In the case of the Tm 4
p core level, in which the principal quantum number is identical with the valence 4
f, the correlation effect is stronger, and the configuration interaction is therefore considered to explain the spectral features. The photoemission spectra for the shallow core level Tm 5
p also show the effect of electron correlation, but weaker than that for Tm 4
p. This has been confirmed by the resonant photoemission spectroscopy taken at Tm 4
d–4
f absorption edges. In addition, the feature of Tm 3
d photoemission spectra is discussed. All the experimental spectra are compared with the calculated ones. It is therefore understood that the electron correlation effect plays an important role on determining the various features in Tm 4
p, 5
p and 3
d photoemission spectra.
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A. Kenfack Jiotsa, T. C. Kofané
2003 Volume 72 Issue 7 Pages
1800-1809
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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We study analytically modulational instability in an extended media, taking the one-dimensional quintic complex Ginzburg–Landau equation model as an example. We show that the quintic term can affect the conditions for modulational instability (MI), and the propagating regime. Numerical simulations demonstrate the validity of analytical predictions. The model presents a rich variety of patterns propagating into the system. The main feature of the travelling shock waves is the propagation of a secondary modulated wave at the same time with a stable plane wave.
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Noboru Miyata, Takashi Imazono, Mihiro Yanagihara, Makoto Watanabe, Ta ...
2003 Volume 72 Issue 7 Pages
1810-1811
Published: July 15, 2003
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Chang Hoon Lee, Dong Keun Oh, Cheol Eui Lee
2003 Volume 72 Issue 7 Pages
1812-1813
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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Takeo Jo
2003 Volume 72 Issue 7 Pages
1814-1815
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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Junko Hatori, Yasumitsu Matsuo, Masaru Komukae, Seiichiro Ikehata, Tos ...
2003 Volume 72 Issue 7 Pages
1816-1817
Published: July 15, 2003
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T. Alagesan, Y. Chung, K. Nakkeeran
2003 Volume 72 Issue 7 Pages
1818
Published: July 15, 2003
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K. W. Wojciechowski
2003 Volume 72 Issue 7 Pages
1819-1820
Published: July 15, 2003
Released on J-STAGE: July 25, 2007
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