Publications (68)
Growth of superconducting MgB2 thin films
K. Ueda, M. Naito
This is the first review on superconducting MgB2 thin films as far as we know.
Fourfold Differential Photoelectron Circular Dichroism
K. Fehre, N. M. Novikovskiy, S. Grundmann +28
We report on a joint experimental and theoretical study of photoelectron circular dichroism (PECD) in methyloxirane. By detecting O 1s-photoelectrons in coincidence with fragment i…
Acceleration of positive muons by a radio-frequency cavity
S. Aritome, K. Futatsukawa, H. Hara +52
Acceleration of positive muons from thermal energy to keV has been demonstrated. Thermal muons were generated by resonant multi-photon ionization of muonium atoms emitted fro…
All-MgB2 Josephson tunnel junctions
K. Ueda, S. Saito, K. Semba +2
Sandwich-type all-MgB2 Josephson tunnel junctions (MgB2/AlOx/MgB2) have been fabricated for the first time with as-grown MgB2 films formed by molecular beam epitaxy. The junctions…
Distillation of hydrogen isotopes for polarized HD target
T. Ohta, S. Bouchigny, J. -P. Didelez +13
We have developed a cryogenic distillation system to purify Hydrogen-Deuteride (HD) gas for a polarized HD target in LEPS experiments at SPring-8. A small amount of ortho-H ($\…
One-dimensional Kondo lattice model as a Tomonaga-Luttinger liquid
N. Shibata, A. Tsvelik, K. Ueda
Arguments are presented that in the one-dimensional Kondo lattice model f-electron spins participate in filling of the Fermi sea. It is shown that in its paramagnetic phase this mo…
HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer
T. Ohta, S. Bouchigny, J. -P. Didelez +13
A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiment…
Time-Resolved Measurement of Interatomic Coulombic Decay in Ne_2
K. Schnorr, A. Senftleben, M. Kurka +24
The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne_2 is determined via an extreme ultraviolet pump-probe experiment…
Tunnel junctions on as-grown superconducting MgB2 thin films
K. Ueda, M. Naito
We demonstrate that good superconductor/insulator/normal-metal tunnel junctions can be fabricated on as-grown superconducting MgB2 thin films. The as-grown films were prepared by c…
Spin-Orbit Torque Switching of Noncollinear Antiferromagnetic Antiperovskite Manganese Nitride MnGaN
T. Hajiri, K. Matsuura, K. Sonoda +3
Noncollinear antiferromagnets have promising potential to replace ferromagnets in the field of spintronics as high-density devices with ultrafast operation. To take full advantage…
Electrical injection and detection of spin-polarized electrons in silicon through an Fe_3Si/Si Schottky tunnel barrier
Y. Ando, K. Hamaya, K. Kasahara +5
We demonstrate electrical injection and detection of spin-polarized electrons in silicon (Si) using epitaxially grown Fe_3Si/Si Schottky-tunnel-barrier contacts. By an insertion of…
Impact of geometrical frustration on charge transport near the Mott transition in pyrochlore (YCd)MoO
S. Iguchi, Y. Kumano, K. Ueda +2
To search for novel spin-charge coupled phenomena in the strongly correlated electron system on a frustration lattice, charge transport and dynamics have been investigated for the…
Efficient Site-specific Low-energy Electron Production via Interatomic Coulombic Decay Following Resonant Auger Decay
M. Kimura, H. Fukuzawa, K. Sakai +7
We identified interatomic Coulombic decay (ICD) channels in argon dimers after spectator-type resonant Auger decay in one of the atoms, using momentu…
Electron-ion-ion coincidence experiments for photofragmentation of polyatomic molecules using pulsed electric fields: treatment of random coincidences
G. Pruemper, K. Ueda
In molecular photofragmentation processes by soft X-rays, a number of ionic fragments can be produced, each having a different abundance and correlation with the emitted electron k…
Coherent control with a short-wavelength Free Electron Laser
K. C. Prince, E. Allaria, C. Callegari +37
XUV and X-ray Free Electron Lasers (FELs) produce short wavelength pulses with high intensity, ultrashort duration, well-defined polarization and transverse coherence, and have bee…
Power-Law Suppression of Phonon Thermal Transport by Magnetic Excitations in a Molecular Quantum Spin Liquid
S. Fujiyama, K. Ueda, Y. Otsuka
We present large-scale ab initio phonon calculations for the molecular quantum spin liquid X[Pd(dmit)2]2. An unusually low average phonon velocity ( 700 {m/s}) and optical modes be…
Spin and charge gaps in the one-dimensional Kondo-lattice model with Coulomb interaction between conduction electrons
N. Shibata, T. Nishino, K. Ueda +1
The density-matrix renormalization-group method is applied to the one-dimensional Kondo-lattice model with the Coulomb interaction between the conduction electrons. The spin and ch…
Soundwave Anomalies in SrCu_{2}(BO_{3})_{2}
S. Zherlitsyn, S. Schmidt, B. Wolf +6
The temperature and high magnetic field dependence of the longitudinal soundwave mode c_{11} in the two dimensional dimer system SrCu_{2}(BO_{3})_{2} is presented. c_{11}(T) shows…
Magnetic field-induced insulator-semimetal transition in a pyrochlore Nd2Ir2O7
K. Ueda, J. Fujioka, B. -J. Yang +6
We have investigated magneto-transport properties in a single crystal of pyrochore-type Nd2Ir2O7. The metallic conduction is observed on the antiferromagnetic domain walls of the a…
Thermodynamic properties of the one-dimensional Kondo insulators studied by the density matrix renormalization group method
N. Shibata, B. Ammon, M. Troyer +2
Thermodynamic properties of the one-dimensional Kondo lattice model at half-filling are studied by the density matrix renormalization group method applied to the quantum transfer m…
Development of a picosecond-timing Cherenkov detector using gaseous photomultiplification
R. Okubo, K. Matsuoka, T. Iijima +9
Photosensitive gaseous detectors with a simple photoelectron multiplication mechanism as resistive plate chambers are expected to offer both large photo coverage and excellent time…
Time-resolved study of resonant interatomic Coulombic decay in helium nanodroplets
A. C. LaForge, R. Michiels, Y. Ovcharenko +30
When weakly-bound complexes are multiply excited by intense electromagnetic radiation, energy can be exchanged between neighboring atoms through a type of resonant interatomic Coul…
Snapshot Observation for 2D Classical Lattice Models by Corner Transfer Matrix Renormalization Group
K. Ueda, R. Otani, Y. Nishio +2
We report a way of obtaining a spin configuration snapshot, which is one of the representative spin configurations in canonical ensemble, in a finite area of infinite size two-dime…
Ferromagnetism and Electronic Structures of Nonstoichiometric Heusler-Alloy Fe_3-xMn_xSi Epilayers Grown on Ge(111)
K. Hamaya, H. Itoh, O. Nakatsuka +6
For the study of ferromagnetic materials which are compatible with group-IV semiconductor spintronics, we demonstrate control of the ferromagnetic properties of Heusler-alloys Fe_3…
Thermodynamic Properties of the S=1/2 Heisenberg Chain with Staggered Dzyaloshinsky-Moriya Interaction
N. Shibata, K. Ueda
Thermodynamic properties of the S=1/2 Heisenberg chain in transverse staggered magnetic field H^y_s and uniform magnetic field H^x perpendicular to the staggered field is studied b…
Pressure and magnetic-field effects on metal-insulator transitions of bulk and domain-wall states in pyrochlore iridates
K. Ueda, J. Fujioka, C. Terakura +1
We have explored the critical metal-insulator phenomena for pyrochlore-type IrO, in which electron correlation strength and magnetic configuration are systematically c…
Theory of Fano-Kondo effect in quantum dot systems: temperature dependence of the Fano line shapes
I. Maruyama, N. Shibata, K. Ueda
The Fano-Kondo effect in zero-bias conductance is studied based on a theoretical model for the T-shaped quantum dot by the finite temperature density matrix renormalization group m…
A new route for enantio-sensitive structure determination by photoelectron scattering on molecules in the gas phase
K. Fehre, N. M. Novikovskiy, S. Grundmann +28
X-ray as well as electron diffraction are powerful tools for structure determination of molecules. Studies on randomly oriented molecules in the gas-phase address cases in which mo…
Photoelectron Angular Distributions for Two-photon Ionization of Helium by Ultrashort Extreme Ultraviolet Free Electron Laser Pulses
R. Ma, K. Motomura, K. L. Ishikawa +19
Phase-shift differences and amplitude ratios of the outgoing and continuum wave packets generated by two-photon ionization of helium atoms are determined from the photoelec…
Susceptibilities of Sr(Cu_(1-x)Zn_x)_2O_3 Studied by Quantum Monte Carlo Simulation
T. Miyazaki, M. Troyer, M. Ogata +2
The effects of non-magnetic impurities randomly doped into a two-leg Heisenberg spin ladder are investigated. Using the continuous time quantum Monte Carlo loop algorithm we calcul…
Spin-wave gap collapse in Rh-doped Sr2IrO4
J. Bertinshaw, J. K. Kim, J. Porras +7
We use resonant inelastic x-ray scattering (RIXS) at the Ir L3 edge to study the effect of hole doping upon the Jeff=1/2 Mott-insulating state in Sr2IrO4, via Rh replacement of the…
Observation and Control of Laser-Enabled Auger Decay
D. Iablonskyi, K. Ueda, Kenichi L. Ishikawa +21
Single photon laser enabled Auger decay (spLEAD) has been redicted theoretically [Phys. Rev. Lett. 111, 083004 (2013)] and here we report its first experimental observation in neon…
Overcoming the space-charge dilemma in low-energy heavy ion beams via a multistage acceleration lens system
M. Nishiura, T. Ido, M. Okamura +3
Low-energy heavy-ion beams are fundamentally limited by severe space-charge divergence, which constrains the transportable beam current to a few microamperes in conventional electr…
Correlation Driven Transient Hole Dynamics Resolved in Space and Time in the Isopropanol Molecule
T. Barillot, O. Alexander, B. Cooper +46
The possibility of suddenly ionized molecules undergoing extremely fast electron hole dynamics prior to significant structural change was first recognized more than 20 years ago an…
Proximate ferromagnetic state in the Kitaev model material -RuCl
H. Suzuki, H. Liu, J. Bertinshaw +17
-RuCl is a major candidate for the realization of the Kitaev quantum spin liquid, but its zigzag antiferromagnetic order at low temperatures indicates deviations from the…
Epitaxial ferromagnetic FeSi/Si(111) structures with high-quality hetero-interfaces
K. Hamaya, K. Ueda, Y. Kishi +3
To develop silicon-based spintronic devices, we have explored high-quality ferromagnetic FeSi/silicon (Si) structures. Using low-temperature molecular beam epitaxy at 130 $^c…
A diagnostic system of 5.7 keV muon beam for muon accelerator
M. Wada, M. Kimura, S. Aritome +28
Realization of a low-emittance muon beam through the acceleration of keV-scale muons requires the injection of a suitably matched beam into an accelerator, since beam mismatch can…
Autoionization dynamics of He nanodroplets resonantly excited by intense XUV laser pulses
Y. Ovcharenko, A. LaForge, B. Langbehn +16
The ionization dynamics of helium droplets in a wide size range from 220 to 10^6 He atoms irradiated with intense femtosecond extreme ultraviolet (XUV) pulses of 10^9 ÷ 10^{12} W/…
Localization of Inner-Shell Photoelectron Emission and Interatomic Coulombic Decay in Ne
K. Kreidi, T. Jahnke, Th. Weber +29
We used Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) to investigate the decay of Ne after K-shell photoionization. The breakup into Ne / Ne shows inter…
Quantum Phase Transition of Organic Spin Liquid Tuned by Mixing Counterions
K. Ueda, S. Fujiyama, R. Kato
We found a plateau in the magnitude of the isolated magnetic moments as a function of the anisotropy of the transfer integral (t'/t) in the gapless quantum spin liquid (QSL) phase…
Nonmagnetic-magnetic transition and magnetically ordered structure in SmS
S. Yoshida, T. Koyama, H. Yamada +5
SmS, a prototypical intermediate valence compound, has been studied by performing high-pressure nuclear magnetic resonance measurements on a S-enriched sample. The observati…
Watching the acetylene vinylidene intramolecular reaction in real time
Y. H. Jiang, A. Senftleben, A. Rudenko +18
It is a long-standing dream of scientists to capture the ultra-fast dynamics of molecular or chemical reactions in real time and to make a molecular movie. With free-electron laser…
Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-ray FEL
P. Salen, P. van der Meulen, H. T. Schmidt +16
We have performed X-ray two-photon photoelectron spectroscopy (XTPPS) using the Linac Coherent Light Source (LCLS) X-ray free-electron laser (FEL) in order to study double core-hol…
Time-resolved chiral X-Ray photoelectron spectroscopy with transiently enhanced atomic site-selectivity: a Free Electron Laser investigation of electronically excited fenchone enantiomers
D. FaccialÃ, M. Devetta, S. Beauvarlet +28
Chiral molecules are widespread in nature, playing a fundamental role in bio-chemical processes and in the origin of life itself. The observation of dynamics in chiral molecules is…
Time-resolved observation of interatomic Coulombic decay induced by two-photon double excitation of Ne
T. Takanashi, N. V. Golubev, C. Callegari +46
The hitherto unexplored two-photon doubly-excited states [Ne()] were experimentally identified using the seeded, fully coherent, intense extreme ultraviolet…
Magnetic Susceptibilities of Spin-1/2 Antiferromagnetic Heisenberg Ladders and Applications to Ladder Oxide Compounds
D. C. Johnston, M. Troyer, S. Miyahara +11
A comprehensive theoretical and experimental study is presented of the magnetic susceptibility versus temperature Ï(T) of spin S = 1/2 two- and three-leg Heisenberg ladders and la…
Evidence for gradual evolution of low-energy fluctuations underlying the first-order structural and valence order in YbPd
R. Nakanishi, T. Fujii, Y. Nakai +6
The valence orders at K and K in the cubic compound YbPd have been investigated by Pd-nuclear magnetic resonance (NMR) measurements. Significant decreas…
Development of portable NMR polarimeter system for polarized HD target
T. Ohta, M. Fujiwara, K. Fukuda +10
A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. T…
Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses
H. Fukuzawa, S. -K. Son, K. Motomura +27
We have investigated multiphoton multiple ionization dynamics of argon and xenon atoms using a new x-ray free electron laser (XFEL) facility, SPring-8 Angstrom Compact free electro…
Photoelectron circular dichroism of O 1-photoelectrons of uniaxially oriented trifluoromethyloxirane: Energy dependence and sensitivity to molecular configuration
G. Nalin, K. Fehre, F. Trinter +25
The photoelectron circular dichroism (PECD) of the O 1s-photoelectrons of trifluoromethyloxirane(TFMOx) is studied experimentally and theoretically for different photoelectron kine…
Fabrication and properties of MgB2/AlOx/MgB2 tunnel junctions
K. Ueda, S. Saito, K. Semba +2
Sandwich-type MgB2 Josephson tunnel junctions (MgB2/AlOx/MgB2) have been fabricated using as-grown MgB2 films formed by molecular beam epitaxy. The junctions exhibited substantial…
Entanglement perturbation theory for the quantum ground states in two dimensions
S. G. Chung, K. Ueda
A simple, general and practically exact method, Entanglement Perturbation Theory (EPT), is formulated to calculate the ground states of 2D macroscopic quantum systems with translat…
Friedel oscillations in the one-dimensional Kondo-lattice model
N. Shibata, K. Ueda, T. Nishino +1
The paramagnetic metallic phase of the one-dimensional Kondo lattice model is studied by the density-matrix renormalization- group method. We observe charge and spin Friedel oscill…
One Dimensional Kondo Lattice Model Studied by the Density Matrix Renormalization Group Method
N. Shibata, K. Ueda
Recent developments of the theoretical investigations on the one-dimensional Kondo lattice model by using the density matrix renormalization group (DMRG) method are discussed in th…
Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet
H. Suzuki, H. Gretarsson, H. Ishikawa +16
Ruthenium compounds play prominent roles in materials research ranging from oxide electronics to catalysis, and serve as a platform for fundamental concepts such as spin-triplet su…
Measuring the frequency of a Sr optical lattice clock using a 120-km coherent optical transfer
F. -L. Hong, M. Musha, M. Takamoto +11
We demonstrate a precision frequency measurement using a phase-stabilized 120-km optical fiber link over a physical distance of 50 km. The transition frequency of the 87Sr optical…
A multiple scattering theoretical approach to time delay in high energy core-level photoemission of heteronuclear diatomic molecules
Y. Tamura, K. Yamazaki, K. Ueda +1
We present analytical expressions of momentum-resolved core-level photoemission time delay in a molecular frame of a heteronuclear diatomic molecule upon photoionization by a linea…
An Internet-enabled technology to support Evolutionary Design
V. V. Kryssanov, H. Tamaki, K. Ueda
This paper discusses the systematic use of product feedback information to support life-cycle design approaches and provides guidelines for developing a design at both the product…
Machine learning applied to single-shot x-ray diagnostics in an XFEL
A. Sanchez-Gonzalez, P. Micaelli, C. Olivier +39
X-ray free-electron lasers (XFELs) are the only sources currently able to produce bright few-fs pulses with tunable photon energies from 100 eV to more than 10 keV. Due to the stoc…
Low-Lying Magnetic Excitation of the Shastry-Sutherland Model
K. Totsuka, S. Miyahara, K. Ueda
By using perturbation calculation and numerical diagonalization, low-energy spin dynamics of the Shastry-Sutherland model is investigated paying particular attention to the two-par…
Observation of spin-orbit excitations and Hund's multiplets in CaRuO
H. Gretarsson, H. Suzuki, Hoon Kim +6
We use Ru -edge (2838.5 eV) resonant inelastic x-ray scattering (RIXS) to quantify the electronic structure of CaRuO, a layered -electron compound that exhibits a…
NMR study of electronic state in CePt3Si
K. Ueda, K. Hamamoto, T. Kohara +2
In this article, we report the temperature dependence of spin-lattice relaxation rates at two Pt sites and one Si site in CePt3Si with a non-centrosymmetric structure center. 1/T1…
Origin of spin-gap in CaVO: effect of frustration and lattice distortion
O. A. Starykh, M. E. Zhitomirsky, D. I. Khomskii +2
We study the origin of spin-gap in recently discovered material CaVO. We analyze the spin- Heisenberg model on the depleted square lattice with nearest neighbor…
Theory of Metal-Insulator Transition in PrRu4P12 and PrFe4P12
S. H. Curnoe, H. Harima, K. Takegahara +1
All symmetry allowed couplings between the 4f^2-electron ground state doublet of trivalent praseodymium in PrRu4P12 and PrFe4P12 and displacements of the phosphorus, iron or ruthen…
Enhanced beam transport via space charge mitigation in a multistage accelerator for fusion plasma diagnostics
M. Nishiura, K. Nakamura, K. Ueda +5
Efficient transport of high-current negative ion beams is critical for accurate plasma potential diagnostics using heavy-ion beam probe (HIBP) systems in magnetically confined fusi…
Epitaxial Growth of a Full-Heusler Alloy CoFeSi on Silicon by Low-Temperature Molecular Beam Epitaxy
S. Yamada, K. Yamamoto, K. Ueda +4
For electrical spin injection and detection of spin-polarized electrons in silicon, we explore highly epitaxial growth of ferromagnetic full-Heusler-alloy Co2FeSi thin films on sil…
Pressure induced evolution of band structure in black phosphorus studied by P-NMR
T. Fujii, Y. Nakai, Y. Akahama +2
Two-dimensional layered semiconductor black phosphorus (BP), a promising pressure induced Dirac system as predicted by band structure calculations, has been studied by P-nuc…
Relativistic Band-Structure Calculations for CeTIn(T=Ir and Co)
T. Maehira, T. Hotta, K. Ueda +1
In order to investigate electronic properties of recently discovered heavy fermion superconductors CeTIn (T=Ir and Co), we employ the relativistic linear augmented-plane-wave (…