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L10-ordered CoPt with a large coercivity (H c) of 13 kOe was demonstrated on Si/SiO2 substrates by hydrogen annealing. Equiatomic 11.2 nm thick (Co/Pt)4 multilayer thin films were fabricated by electron-beam evaporation and were annealed at 500 °C–900 °C for 10–90 min under an Ar/H2 mixed gas atmosphere. The annealing temperature and time dependences of the crystal structures, magnetic properties, and surface morphologies of the films were systematically analyzed based on the experimental results obtained from grazing incidence X-ray diffraction (GI-XRD), vibrating sample magnetometer, and scanning electron microscope, respectively. Hydrogen annealing effectively promoted the out-of-plane c-axis orientation of L10-ordered CoPt compared to the vacuum annealing according to the GI-XRD patterns. A maximum H c of 13.3 kOe was obtained in L10-ordered CoPt with angular-outlined isolated grains by hydrogen annealing at 800 °C for 60 min, where the c-axis of L10-ordered CoPt was randomly distributed.

L12-ordered CoPt3 and L10-ordered CoPt are formed in electron-beam-deposited (Co/Pt)4 multilayer thin films with and without a Ti underlayer, respectively, on Si/SiO2 substrates by rapid thermal annealing. The crystal structures, magnetic properties, and surface morphologies of the films are investigated by grazing incidence X-ray diffraction (GI-XRD), vibrating sample magnetometer (VSM), and scanning electron microscope (SEM), respectively. In the film without a Ti underlayer, L10-ordered CoPt with an isolated round grain structure is confirmed, showing an in-plane coercivity of 2.7 kOe. In contrast, in the film with a Ti underlayer, L12-ordered CoPt3 is confirmed together with Co-rich A1-disordered CoPt, showing an in-plane coercivity of 500 Oe, which exhibits an angular-outlined continuous film structure. The three sets of experimental results from GI-XRD, VSM, and SEM coincide well with each other.

The crystal structure of BaFe2S3 is determined up to ~12 GPa by means of x-ray powder diffraction experiments using synchrotron radiation at room temperature. BaFe2S3 is the first superconductor in iron-based ladder compounds, showing the critical temperature at T c = 24 K under 11.6 GPa. The superconductivity emerges on the application of pressure after suppressing an antiferromagnetic Mott insulating state. The atomic positions in the superconducting state remain hitherto unknown experimentally. We found significant changes of structural parameters: shrinkage of the Fe-ladder unit and decreasing height of the S atom position from the Fe plane. Moreover, a reduction of the S–S distance between the ladders was observed under pressure. The pressure dependence of the structural parameters is strikingly different from the prediction of the band calculation.

We measured the Raman scatterings from various single-walled carbon nanotube (SWNT) samples over a wide temperature range (4–1000 K). The G-band peaks showed a clear temperature dependence, namely, decrease in the Raman shift frequency and broadening of the peak width as temperature increases. The main G-band peak (G+ peak) showed universal temperature dependence in Raman shift for the various SWNT samples and for the three excitation laser wavelengths (488.0, 514.5, and 632.8 nm), although the G-band features changed depending on the SWNT samples and excitation laser wavelengths owing to the resonance Raman effects. The Raman shift, peak width, and intensity of the radial breathing mode (RBM) peaks also exhibited temperature dependence. At high temperatures, undefined RBM peaks appeared, which could not be assigned to specific chiralities, and showed opposite temperature dependence in their intensities. The intensities of the RBM peaks are strongly enhanced by the resonance Raman effects, and the temperature may change the resonance Raman conditions.

The stability and transition of a pair of planar counter-rotating vortices in a confined region are investigated numerically. Direct numerical simulations in a rectangular box: D = [0,2kπ] × [0,π], where k is an aspect ratio, are done with symmetric external forcing. A pair of steady symmetric counter-rotating vortices are generated under weak forcing while they become unstable with stronger forcing. Special attention is paid to the effect of the aspect ratio k on the stability and the transition. It is found that a steady asymmetric pattern appears for k > k0 ≈ 0.5 while an oscillating asymmetric pattern for k < k0. In particular, the symmetric vortices become very stable around k = 0.5 (i.e. the square region). Linear stability analysis of a model flow similar to the symmetric vortices generated in the numerical simulations gives the same tendency as the above findings. The results suggest that the singular property of the stability at k = k0 ≈ 0.5 is mainly dependent on the aspect ratio k of the region but rather independent of the superficial difference of the vorticity distribution.

The instability of two-dimensional periodic flows to three-dimensional disturbances is investigated. The problem is formulated for general periodic flows, and the eigenvalue problem is solved numerically for the rhombic cell flow with aspect ratio k = 0.5 and 1.0. The result of numerical calculation shows that the three-dimensional disturbance does not cause a change in the values of the critical Reynolds number Rc. Some decrease in damping rate is found for the three-dimensional disturbances of some set of wavenumbers, but it is not sufficient to change the value of Rc.

Static deformation of free surface is investigated for horizontal magnetic fluid layer in the presence of applied magnetic field induced by circular electric current situated horizontally below the layer. Shape of the deformed free surface is found by numerical calculation for various current intensity and size of circuit. The problems for a straight line current and a magnetic dipole are solved separately.

From 29–31 August 2013, the 1st International Conference on Light and Particle Beams in Materials Science, LPBMS 2013, took place in the Tsukuba International Congress Center in the city of Tsukuba, Japan. The conference was a continuation of the international series Synchrotron Radiation in Materials Science (SRMS), which started in 1994. The last one, SRMS-7, was held in Oxford UK 11–14 July 2010, where the International Advisory Committee (IAC) recommended the conference be enlarged to incorporate Materials Research from Neutron, Muon, and Slow Positron Sources, as well as the science emerging from Synchrotron Light Sources. The conference brought together contributions from academics and industrial researchers with a diverse background and experience from the physics, chemistry and engineering communities. The topics covered in the LPBMS2013 include strongly correlated electron systems, magnetism and magnetic materials, soft matter, interface and surface defects, catalysts, biomaterials, and ceramics. In the 3-day scientific program, the conference consisted of 9 plenary talks, 33 invited talks, 20 oral presentations, and 126 poster presentations. We are pleased to publish the proceedings of the LPBMS2013 in this volume of Journal of Physics: Conference Series. This volume contains 58 papers representing the work that was presented and discussed at the conference. We hope that this volume will promote further development of this interdisciplinary materials research emerging from synchrotron light, neutron, muon, and slow positron sciences. Finally, we would like to thank the International Advisory Committee (Chair: Professor G N Greaves), sponsors, all the participants and contributors for making possible this international meeting of researchers. Reiji Kumai & Youichi Murakami Details of the program and organizing committees are available in the pdf

Resonant soft X-ray scattering measurements become one of powerful techniques to probe charge, orbital and spin orderings in strongly correlated electron systems. We have developed new in-vacuum diffractometer with a large vacuum chamber to solve experimental limitations of in-vacuum measurement in soft X-ray energy region, and for future instrumental developments. In this paper, the features of the diffractometer are presented.

We have constructed a soft X-ray diffractometer with a 7.5-T superconducting magnet in order to study ordered electronic structures under high magnetic field. In this paper, we present the features of this system and an example of resonant soft X-ray scattering measurement under the magnetic field of (LaMnO3)3(SrMnO3)3 superlattice with a remarkable negative magnetoresistance effect.

There has been a recent increasing interest in a topological spin texture, so-called skyrmion crystal, stimulated by small-angle neutron scattering and Lorentz-TEM studies. For the purpose of measuring the resonant soft x-ray magnetic scattering to characterize the distribution of magnetic moments with long-wavelength in range of a few tens to hundreds nm, we have developed a diffractometer for small angle soft x-ray scattering. The principle features of the diffractometer and the initial experimental results are presented.

In resonant soft X-ray scattering measurement, we need the detector which can tune its solid angle continuously in vacuum. We have constructed a 4-blade-slit detector system for high vacuum and set it in the quasi-3-axis diffractometer. With this system, we have studied two magnetic structures in antiferromagnetic insulator La1.5Ca0.5CoO4 by Co L2,3-edge resonant soft X-ray scattering. We revealed that the underlying Co electronic structures for these magnetic structures are the same, since the observed energy spectra take the same lineshape.

In this study we have investigated dopant effects on a typical charge-orbital ordered state in a single layered manganite La0.5Sr1.5MnO4 using x-ray diffraction and magnetization measurement. We have studied how the orbital ordered states are affected by the 3% substitution of Cr, Fe and Ga ions for Mn ions. It is revealed that the orbital ordered states are suppressed by the magnetic impurities and the phase-separated state with charge-orbital ordering and ferromagnetic cluster and/or spin-cluster-glass state emerge in the all impurity doped compounds.

Neutron scattering studies reveal that a crystal-field-splitting ground state of Pr3+ 4f2 electrons in a partially filled PrxFe4Sb12 (x < 1) is a triplet. A magnetically ordered structure below 4 K consists of both magnetic moments at the Pr and Fe sites, in contrast to the x = 1 system without any magnetic ordering due to the 4f-electron singlet ground state.

Crystal field states of Pr 4f electrons of PrOs4P12 and PrRu4Sb12 were investigated by inelastic neutron scattering. Different spectral widths between two excitations from the ground state singlet to the triplets and their temperature evolutions are well reproduced by the theory based on the exchange coupling between 4f and conduction electrons (Becker K W et al. 1977 Z. Physik B 28 9). Shift of level energies by around 1 meV below 60 K were also observed. The results support the p-f hybridization effect in Pr-filled skutterudites.

We have performed inelastic neutron scattering and magnetic susceptibility measurements on Pr(Ru1−xRhx)4P12 (0 ≤ x ≤ 0.15), in which the antiferro-multipole ordering of PrRu4P12 is gradually suppressed with increasing x. The saturation of magnetic susceptibility at low temperature suggests that all the 4f-electron ground states are singlet for x ≥ 0.03, in contrast to the triplet and singlet ground states in the ordered phase of PrRu4P12. Neutron experiments show the presence of two types of crystal field (CF) level schemes: a temperature-dependent one similar to one of those observed in PrRu4P12 as signatures of the ordering, and an additional temperature-independent one indicating the existence of Pr ions which do not contribute to the ordering. Rh-substitution seems to have two effects: a local effect causing temperature-independent CF levels of Pr ions, and a wide-range effect causing switch of ground state. The ordering in low Rh-content compounds arises from the inequivalent CF level schemes that allow conserving the antiferro-type ordering pattern of multipoles through thermal excitation, despite the common ground state in compounds with x ≥ 0.03.

We present a X-ray diffraction study of Pr(Ru1−xRhx)4P12 (x = 0, 0.05), which exhibit a metal-nonmetal transition at about 50–60 K. Superlattice reflections which are related to [Ru,Rh] and P atom displacements could be observed below the transition temperature. In PrRu4P12, these displacements are found to increase gradually as the temperature decreases, in agreement with previous studies. In Pr(Ru0.95Rh0.05)4P12, the [Ru0.95Rh0.05] and P atom displacements first increase with decreasing temperature below 50 K, but nearly cancel at lowest temperatures. We discuss this unexpected structural behavior by considering the Pr 4f electron states in the Pr(Ru1−xRhx)4P12 compounds.

The orbital ordered states of V 3d in RVO3 (R=Y, Tb) have been investigated by a resonant x-ray scattering (RXS) technique. The RXS signals at (0 1 1) were measured near the V K-edge energy in the G-type orbital ordered (G-OO) phase. We found two kinds of the RXS signals, which reflect the orbital state and the local crystal symmetry. The former signal disappears in the orbital disordered phase, while the latter still survives. Moreover, the signals have different azimuthal angle dependence. Using the dependence of the RXS signal reflecting the orbital state, we evaluated the orbital ordered structure in the G-OO phase. Consequently, we succeeded in determining the G-type orbital arrangement of V orbitals by the RXS technique.

Dynamics of rare-earth ions in filled skutterudite compounds PrT4Sb12 (T = Ru and Os) has been investigated by a neutron inelastic scattering technique. We found an optical mode located at extremely low energy around 4 meV exhibiting apparent softening behavior by 10 - 30% from 300 to 10 K. This softening mode is attributed to the motion of the filled Pr ions bound in anharmonic potential within the Sb cage. In addition, quasielastic responses near the Brillouin zone center indicate relaxation modes. These features can be explained in terms of a mode coupling scenario involving the motion of the filled Pr ions with huge amplitude.

We report an adjustable saturable absorber based on vertically aligned single-walled carbon nanotubes (SWNTs). Using the low-temperature alcohol catalytic chemical vapor deposition (CVD) method, high-quality vertically aligned SWNTs were directly synthesized onto quartz substrates. The saturable absorption is adjustable by changing the decline angle of the substrate. We applied it as a mode-locker in the passively mode-locked fiber lasers, and optimized the operation by declining the vertically aligned SWNT sample.

Orbital excitations in orbital-ordered transition metal oxides are investigated theoretically and experimentally. Characteristic differences in the collective orbital excitations, termed orbital waves, between the eg and t2g systems are clarified. As a probe to detect the orbital excitations, the scattering processes for the Raman scattering and the resonant and non-resonant inelastic x-ray scatterings are proposed and their scattering cross-sections are calculated. The orbital excitations in hole-doped and undoped manganites are examined experimentally by using resonant inelastic x-ray scattering. The obtained experimental results are compared with the theoretical calculations.

Synchrotron x-ray measurements were done on the charge ordered state of La1-x Sr x MnO3 (x∼0.12). In accordance with previous neutron diffraction study, super-lattice reflections which double the b-axis were observed. From the extinction rule of the super-lattice reflections, layer-type charge ordering pattern is plausible. Temperature dependence of the super-lattice peaks might indicate that a certain kind of competition exists in this system.

Hole-doped lanthanum manganites La1-x Sr x MnO3 have been revisited since the discovery of colossal magnetoresistance (CMR). In this system, orbital as well as spin and charge degrees of freedom have attracted much attention. However, direct observation of orbital ordering (OO) is very difficult and there have been few experiments. Recently, Murakami et al. [Phys. Rev. Lett. 80 (1998) 1932, Phys. Rev. Lett. 81 (1998) 582] observed the azimuthal-angle dependence of OO superlattice peaks in La0.5Sr1.5MnO4 and LaMnO3 by resonant x-ray diffraction, which is sensitive to the anisotropy of the structure factor. It is also known that the OO peak changes the polarization of photons from σ to π', which was also observed by Murakami et al. in LaMnO3. We confirmed that the (0 3 0) reflection of La0.88Sr0.12MnO3 is an OO superlattice peak using synchrotron resonant x-ray diffraction, and then carried out polarization analysis of the OO superlattice peak. While the azimuthal-angle dependence of (0 3 0) shows a clear two-fold dependence, the polarization dependence is somewhat obscure. We found that the peak consists of two parts, one of which shows a σ→π' polarization and the other shows a σ→σ' behaviour. We speculate the latter is an extrinsic contamination, though the origin is unknown.

A direct numerical simulation of the Navier-Stokes equation is performed in order to investigate the small scale structure of turbulence at moderately large microscale Reynolds numbers 40–140, using the spectral method with 3403 modes starting from a high-symmetric flow. It is shown that the small scale motion is statistically isotropic. The probability density distribution of the velocity is Gaussian, while those of the velocity gradients and the vorticity are not Gaussian but have long exponential tails. The moments of the velocity gradients are expressed in terms of the gamma function, and the ratio of the moments of the velocity gradients of successive orders increases linearly with the order. A comparison is made with a laboratory experiment.

Memory phenomena in the ordered state of triangular ferromagnets CoCl2- and NiCl2 graphite intercalation compounds (GIC) are investigated by the measurement of thermoremanent and field induced magnetizations. The results are compared with the theoretically expected one for spin glass. Measurement for a typical spin glass CuMn alloy is undertaken for a comparison. An anomalous memory is revealed in the intermediate state, which shows apparently characteristics of both ordered and disordered states.