著者

Yonezawa Shingo Kajikawa Tomohiro Maeno Yoshiteru

出版者

American Physical Society

雑誌

Physical Review Letters (ISSN:00319007)

巻号頁・発行日

vol.110, no.7, 2013-02

被引用文献数

94

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ルテニウム酸化物における超伝導の一次相転移の発見 -超伝導と磁場の未知の相互作用メカニズムの存在を示唆-. 京都大学プレスリリース. 2013-02-15.

著者

Okada Susumu Shiraishi Kenji Oshiyama Atsushi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.90, no.2, pp.026803, 2003-01

被引用文献数

33 21

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Based on total-energy electronic-structure calculations within the density-functional theory, we find that a high spin state is realized for an ultimate dangling bond unit on an otherwise hydrogen-covered Si(111) surface. We further propose a systematic method of constructing nanometer-scale dangling bond networks that exhibit the ferrimagnetic spin ordering. The interplay between the electron-electron interaction and the surface reconstruction is elucidated.

著者

Boero Mauro Parrinello Michele Terakura Kiyoyuki Ikeshoji Tamio Liew Chee Chin

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.90, no.22, pp.226403, 2003-06

被引用文献数

157 118

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A first principles study of a hydrated electron in water at ordinary and supercritical conditions is presented. In the first case, the electron cleaves a cavity in the hydrogen bond network in which six H2O molecules form the solvation shell. The electron distribution assumes an ellipsoidal shape, and the agreement of the computed and the experimental optical absorption seems to support this picture. At supercritical conditions, instead, the H-bond network is not continuous and allows us to predict that the electron localizes in preexisting cavities in a more isotropic way. Four water molecules form the solvation shell but the localization time shortens significantly.

著者

Sato T. Matsui H. Takahashi T. Ding H. Yang H.-B. Wang S.-C. Fujii T. Watanabe T. Matsuda A. Terashima T. Kadowaki K.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.91, no.15, pp.157003, 2003-10

被引用文献数

99 110

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We report a systematic high-resolution angle-resolved photoemission spectroscopy on high-Tc superconductors Bi2Sr2Can-1CunO2n+4 (n=1–3) to study the origin of many-body interactions responsible for superconductivity. For n=2 and 3, a sudden change in the energy dispersion, so called “kink”, becomes pronounced on approaching (π,0) in the superconducting state, while a kink appears only around the nodal direction in the normal state. For n=1, the kink shows no significant temperature dependence even across Tc. This could suggest that the coupling of electrons with Q=(π,π) magnetic mode is dominant in the superconducting state for multilayered cuprates, while the interactions at the normal state and that of single-layered cuprates have a different origin.

著者

Okada Susumu Oshiyama Atsushi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.91, no.21, pp.216801, 2003-11

被引用文献数

73 70

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We report total-energy electronic-structure calculations that provide energetics and electronic structures of double-walled carbon nanotubes consisting of semiconducting (n,0) nanotubes. We find that optimum spacing between the walls of the nanotubes is slightly larger than the interlayer spacing of the graphite. We also find that the electronic structures of the double-walled nanotubes with the inner (7,0) nanotube are metallic with multicarrier characters in which electrons and holes exist on inner and outer nanotubes, respectively. Interwall spacing and curvature difference are found to be essential for the electron states around the Fermi level.

著者

Aoki S. Fukugita M. Hashimoto S. Ishikawa K-I. Ishizuka N. Iwasaki Y. Kanaya K. Kaneko T. Kuramashi Y. Okawa M. Onogi T. Tsutsui N. Ukawa A. Yamada N. Yoshié T.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.91, no.21, pp.212001, 2003-11

被引用文献数

63 155

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We present an unquenched lattice calculation for the B0-B̅ 0 transition amplitude. The calculation, carried out at an inverse lattice spacing 1/a=2.22(4)  GeV, incorporates two flavors of dynamical quarks described by the O(a)-improved Wilson fermion action and heavy quarks described by nonrelativistic QCD. Particular attention is paid to the uncertainty that arises from the chiral extrapolation, especially the effect of pion loops, for light quarks, which we find could be sizable for the leptonic decay constant, whereas it is small for the B parameters. We obtain fBd=191(10)(-22+12)   MeV, fBs/fBd=1.13(3)(-2+13), BBd(mb)=0.836(27)(-62+56), BBs/BBd=1.017(16)(-17+56), and ξ=1.14(3)(-2+13), where the first error is statistical, and the second is systematic, including uncertainties due to chiral extrapolation, finite lattice spacing, heavy quark expansion, and perturbative operator matching.

著者

Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.91, no.20, pp.206401, 2003-11

被引用文献数

27 22

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The displacement of an oxygen atom in pure α quartz is studied via first-principles molecular dynamics. The simulations show that when an O atom in a Si-O-Si bridge is moved away from its original equilibrium position, a new stable energy minimum can be reached. Depending on the spin state and charge Q of the system, this minimum can give rise to either a threefold oxygen (singlet ground state and Q=+1) or to an unsaturated Si atom carrying a dangling bond (triplet state). In the latter case, the hyperfine parameters associated with the 29Si dangling bond are in rather good agreement with electron paramagnetic resonance/electron nuclear double resonance experiments.

著者

Kanda A. Baelus B. J. Peeters F. M. Kadowaki K. Ootuka Y.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.93, no.25, pp.257002, 2004-12

被引用文献数

233 187

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The response of a mesoscopic superconducting disk to perpendicular magnetic fields is studied by using the multiple-small-tunnel-junction method, in which transport properties of several small tunnel junctions attached to the disk are measured simultaneously. This allows us to make the first experimental distinction between the giant vortex states and multivortex states. Moreover, we experimentally find a magnetic-field induced rearrangement and combination of vortices. The experimental results are well reproduced in numerical results based on the nonlinear Ginzburg-Landau theory.

著者

Tomita S. Andersen J. U. Bonderup E. Hvelplund P. Liu B. Brøndsted Nielsen S. Pedersen U. V. Rangama J. Hansen K. Echt O.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.94, no.5, pp.053002, 2005-02

被引用文献数

38

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We have measured the near-infrared absorption spectrum for isolated C ions at room temperature. Two bands, at 9145 cm-1 and 10460 cm-1, have been identified in addition to the main absorption band at 9382 cm-1, seen also at low temperature in a matrix. An interpretation based on the theory of dynamic Jahn-Teller effects is proposed.

著者

Kokubo N. Kadowaki K. Takita K.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.95, no.17, pp.177005, 2005-10

被引用文献数

57

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We present a mode locking (ML) phenomenon of vortex matter observed around the peak effect regime of 2H-NbSe2 pure single crystals. The ML features allow us not only to trace how the shear rigidity of driven vortices persists on approaching the second critical field, but also to demonstrate a dynamic melting transition of driven vortices at a given velocity. We observe the velocity dependent melting signatures in the peak effect regime, which reveal a crossover between the disorder-induced transition at small velocity and the thermally induced transition at large velocity. This uncovers the relationship between the peak effect and the thermal melting.

著者

Okada Susumu Oshiyama Atsushi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.95, no.20, pp.206804, 2005-11

被引用文献数

45 43

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A total-energy electronic-structure calculation is performed to explore energetics and electronic structures of nanotubes adsorbed on metal surfaces. We find that the charge transfer from metal surfaces to the nanotubes takes place depending on both the electronic structures of the adsorbed nanotubes and the work functions of the metal surfaces. In addition, we also find a substantial hybridization between the electron states of metal atoms and those of the nanotubes, which results in the metal-induced inhomogeneous charge distribution in the nanotubes.

著者

Umeda T. Son N. T. Isoya J. Janzén E. Ohshima T. Morishita N. Itoh H. Gali A. Bockstedte M.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.96, pp.145501, 2006-04

被引用文献数

70

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The metastability of vacancies was theoretically predicted for several compound semiconductors alongside their transformation into the antisite-vacancy pair counterpart; however, no experiment to date has unambiguously confirmed the existence of antisite-vacancy pairs. Using electron paramagnetic resonance and first principles calculations we identify the SI5 center as the carbon antisite-vacancy pair in the negative charge state (CSiV_C^-) in 4H-SiC. We suggest that this defect is a strong carrier-compensating center in n-type or high-purity semi-insulating SiC.

著者

Kanazawa Ken Taninaka Atsushi Takeuchi Osamu Shigekawa Hidemi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.99, no.21, pp.216102, 2007-11

被引用文献数

15 13

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The structures of two competing phases and their interrelationship in the self-organization of glycine molecules on a Cu(100) surface were clarified. Despite their similar structural energies predicted using first-principles calculation, completely different mechanisms were found to stabilize the two phases. The balance and coordination of the two mechanisms that induce a variety of self-assembled structures in this attractive system were revealed. Furthermore, the importance of the microscopic arrangement of the molecules in designing the macroscopic electronic structures was directly demonstrated.

著者

Feng Xu Aoki Sinya Fukaya Hidenori Hashimoto Shoji Kaneko Takashi Noaki Jun-ichi Shintani Eigo JLQCD Collaboration

出版者

American Physical Society

雑誌

Physical Review Letters (ISSN:00319007)

巻号頁・発行日

vol.109, no.18, pp.182001, 2012-11

被引用文献数

20 8

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We perform a nonperturbative calculation of the π0→γγ transition form factor and the associated decay width using lattice QCD. The amplitude for a two-photon final state, which is not an eigenstate of QCD, is extracted through a Euclidean time integral of the relevant three-point function. We utilize the all-to-all quark propagator technique to carry out this integration as well as to include the disconnected quark diagram contributions. The overlap fermion formulation is employed on the lattice to ensure exact chiral symmetry on the lattice. After examining various sources of systematic effects, except for a possible discretization effect, we obtain Γπ0→γγ=7.83(31)(49)  eV for the pion decay width, where the first error is statistical and the second is our estimate of the systematic error.

著者

Konabe S. Matsuda K. Okada S.

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.109, no.18, pp.187403, 2012-10

被引用文献数

9 4

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We theoretically study the phase relaxation of excitons in doped single-walled carbon nanotubes caused by elastic scattering between an exciton and an electron. Our calculation of the spectral linewidth, that is the inverse of the scattering rate, demonstrates that this dephasing process is unexpectedly suppressed in doped single-walled carbon nanotubes, giving rise to anomalous nonlinear behavior as a function of the electron density. A detailed investigation reveals that the logarithmic correction of the exciton self-energy plays a critical role in the exciton-carrier scattering dynamics.

著者

Yoshinobu Jun Kawai Maki Imamura Issei Marumo Fumiyuki Suzuki Ryochi Ozaki Hiroyuki Aoki Masaru Masuda Shigeru Aida Misako

出版者

American Physical Society

雑誌

Physical Review Letters (ISSN:00319007)

巻号頁・発行日

vol.79, no.20, pp.3942-3945, 1997-11-17

被引用文献数

29

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Evidence for a molecule-substrate hybridized state near the Fermi level EF is presented for Pd(110)- c(4x2)-benzene. Observed images of adsorbed benzene near EF by scanning tunneling microscopy consist of two elongated protrusions separated by a single nodal depression with C2 symmetry. The existence of a benzene derived state near EF is also observed by metastable atom electron spectroscopy, and it is assigned to the antibonding states between the 1e1g molecular orbital of benzene and the Pd 4d orbitals by ab initio molecular orbital calculations.