Local chemical state change in Co–O resistance random access memory

Kelvin probe force microscopy (KFM) and conductive atomic force microscopy (C‐AFM) together with micro X‐ray photoelectron spectroscopy (XPS) were performed for the stacking structure comprising of the transition metal oxide Co–O and metal electrode, which exhibits large reproducible resistance switching. The application of the external voltage by the C‐AFM cantilever decreases the resistance of Co–O, which well accords with the non‐polar forming process observed in the Pt/Co–O/Pt trilayer, known as the candidate of resistance random access memory (ReRAM). Furthermore, the KFM and micro XPS experimentally revealed that the local reductive reaction of Co–O possibly nucleates the defect related energy levels which dominates the current conduction in the low resistance state. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Can a linearly polarized light beam polarize atomic spin?

Lax et al. [Phys. Rev. 11 (1975) 1365] discovered that a light beam in vacuum is not a transverse wave but does have a longitudinal field component. We investigate atomic and molecular electric dipole transitions induced by such a light beam, in particular, linearly polarized in a transverse plane. We derive the selection rules and the transition rates for various quantization axes using the paraxial approximation up to the first order of 1/kw, where k is the wave number and w is the transverse size of the light beam. The light beam is able to yield atomic spin polarization in the direction perpendicular to both the optical axis and the transverse electric field, and its magnitude is approximately 1/kw times that generated by a circularly polarized light wave with the similar intensity.     

Investigation of the relationship between the ionic conductivity and the local structures of singly and doubly doped ceria compounds using EXAFS measurement

The oxide ionic conductivity measurements of singly and doubly doped ceria compounds were carried out. Singly and doubly doped ceria used in this study were Ce_0.8Ln_0.2O_1.9 (Ln=Y, Sm, Nd, or La) and Ce_0.8La_0.1Y_0.1O_1.9, respectively. Lattice constants of these compounds were in proportion to the ionic radius of the dopant(s). The doubly doped ceria compound showed oxide ionic conductivity comparative to the average of that of each corresponding singly doped sample. This finding indicates that the conductivity is influenced by both dopants in the doubly doped compounds. The extended X-ray absorption fine structure (EXAFS) study showed that the coordination number of oxide ions at the nearest neighbor of cation was related to the ionic conductivity. It was found that the conductivity gave the highest value when oxygen vacancies were randomly distributed in the lattice. This indicates that the local structure seriously affects oxide ionic conduction in singly and doubly doped ceria compounds.     

Precise determination of Mg/Fe ratios applicable to terrestrial olivine samples using Raman spectroscopy

The relationship between Mg# [ = 100 Mg/(Mg + Fe) in mol] and the Raman shift was analyzed precisely for olivine [(Mg, Fe)₂SiO₄] samples with Mg# between 100 and 62.8. Two prominent peaks at 826–820 cm⁻¹ (peak 1) and 858–849 cm⁻¹ (peak 2) and three subordinate peaks at 883–881 cm⁻¹ (peak 3), 920–914 cm⁻¹ (peak 4), and 967–951 cm⁻¹ (peak 5) were observed to shift monotonously to lower wavenumbers with decreasing Mg#. The ΔMg#( = Mg#_ref − Mg#) versus Δν(= ν_ref − ν) can be linearly regressed for each peak as ΔMg# = A Δν, where ν is a peak wavenumber of olivine with Mg# ranging from 100 to 62.8, and ν_ref is that of olivine with a reference value of Mg#, namely, Mg#_ref. We set Mg#_ref as 100 (i.e.pure forsterite Mg₂SiO₄) whereas A is a regression parameter (5.789, 4.294, 12.34, 6.348, and 2.09, respectively,for peaks 1, 2, 3, 4, and 5). This equation enables us to avoid small inter‐laboratory differences of wavenumber calibration. The equation for peak 2 yields estimations of Mg# in geologically satisfactory precision, ± 1 Mg# (1σ) in the Mg# range of 100–62.8. Copyright © 2011 John Wiley & Sons, Ltd.     

Applying a Mode Selector to Improve the Pulse-Compression Performance of Asymmetric-Coupled-Waveguide-Based Dispersion Compensators

An InGaAsP slab-type asymmetric-coupled-waveguide-based dispersion compensator with a mode selector has been designed and fabricated. The mode selector is necessary to select either a symmetric [with a positive group-velocity dispersion (GVD)] or antisymmetric (with a negative GVD) supermode. These supermodes exist simultaneously in the dispersion-compensation region of the device. Pulse-compression experiments were used to test the dispersion compensator, evaluating the function of the mode selector. A theoretical study of the experimental results shows that the mode selector obtains a very strong selectivity (nearly 100%) for the antisymmetric supermode.     

Size Effect of the Immediate Surround for the Border between the Natural and Unnatural Object Color Appearance

The border luminance of the test stimulus between the natural and unnatural object color, y_ynB_u was obtained for different spatial sizes of the immediate surround to prove that _nB_u can be determined based on a new recognized visual space of illumination (RVSI) that is assumed to be constructed for the immediate surround separately from the RVSI for the subjects room itself. The _nB_u of five test stimuli were determined for six different sizes covering from zero to 1866 cm² with four different lightnesses, N4, N6 and N8, while keeping the room illuminance constant at 100 or 600 lx. The results showed that luminance of the border _nB_u gradually decreased as the size of the immediate surround was increased and that the decrease was larger for immediate surround with lower lightness. The results were interpreted as showing a new RVSI constructed for the spatial extent of the immediate surround of the test stimulus, and the RVSI was more completely constructed for larger spatial size of the immediate surround. © 2005 The Optical Society of Japan     

3 dB squeezing by single-pass parametric amplification in a periodically poled KTiOPO4 crystal

We present the experimental observation of pulsed squeezed light from a degenerate optical parametric amplifier pumped by a second harmonic of a continuous-wave mode-locked Nd:YVO4 laser. With a single pass through a 10 mm long periodically poled KTiOPO4 crystal, the classical parametric gain of 11 is observed. The measured noise reduction in the quiet quadrature is 3.2 dB below the shot-noise level.     

Effects of entanglement on the scattering intensity of neutron compton scattering by a proton pair in solids

We calculate scattering functions S(q-->,omega) of neutron Compton scattering (NCS) for a proton (deuteron) pair in the entangled state caused by the indistinguishability of particles. From the calculation, it is concluded that the effect of entanglement on the scattering intensity is undetectable in NCS experiments because of their high energy transfer and broad energy resolution.     

Optical testing of star sensor (II): Alignment of star sensor from off-line pictures taken in orbital test

Alignment error of an image sensor relative to the optical axis of a star sensor head and alignment errors between four heads were calculated from pictures taken in an orbital experiment. When comparing the image sensor alignment parameters in the orbital test and a ground test, both values matched well. By determining the relative relationship of the four heads using four pictures taken at the same moment in orbit and uploading the parameters to the star sensor system in orbit, the estimated attitude error was improved from 0.29 to 0.17°, though the accuracy was limited by the ±0.2° determination accuracy of the satellite itself. We estimated the attitude determination accuracy from separation angles between boresights of the four heads, calculated from pattern matching between downloaded pictures and a star catalogue. The estimated accuracy, in terms of potential optical performance, was 0.60 arcmin at 3σ, which is sufficient to satisfy the specification of 1 arcmin.