Observation of single-spin transport in an island-shaped CoFeB double magnetic tunnel junction prepared by magnetron sputtering

The Co₄₀Fe₄₀B₂₀(CFB)/MgO/CFB/MgO/CFB-based multilayer was prepared by conventional magnetron sputtering and utilised in the fabrication of double magnetic tunnel junctions (DMTJs) for which the middle CFB layers were island-shaped. By analysing the magnetic property of the CFB islands with Langevin’s equation, it was possible to identify their diameters of 7.6, 8.9 and 11.0 nm; accordingly submicron-scaled DMTJs were fabricated to investigate single-spin transport phenomena. The coulomb staircase and the oscillatory tunnel magnetoresistive (TMR) were able to be observed at 6 K, where the TMR ratio was enhanced up to 60%, which is the highest value ever achieved in this structure.     

Simulation of 200–400 Me V/u 12C+12C elastic scattering on SHARAQ spectrometer

In order to further obtain the information of three-body force(TBF) from 200–400 Me V/u12C+12C elastic scattering, we plan to perform this experiment on a SHARAQ spectrometer. Based on the experimental condition of the Radioactive Ion Beam Factory(RIBF)-SHARAQ facility, a simulation is given to find a compromise between the better energy and angular resolutions, and higher yield by optimizing the target thickness, beam transport mode, beam intensity and angular step. From the simulation, we found that the beam quality mainly limits the improvements of energy and angular resolutions. A beam tracking system as well as a lateral and angular dispersionmatching technique are adopted to reduce the influence of beam quality. According to the two angular settings of SHARAQ as well as the expected cross sections on the basis of the theoretical model, the energy and angular resolutions, and statistical accuracy are estimated.     

Studies of Intermolecular Interaction in Binary Nematic Mixtures of p-Methoxybenzylidene—p′-n-Butylaniline and p-Cyano-p′-n-Pentylbiphenyl by Dielectric Relaxations

Anisotropic dielectric relaxations at the nematic state under magnetic field and viscosities at the isotropic state were measured in MBBA-CPB systems with various mole% of CPB. The intermolecular interaction in the systems with different mole% of CPB was estimated by the MaierSaupe theory from the dielectric relaxations and the viscosities. A long range-intermolecular interaction increased anomalously near the two CPB concentrations exhibiting the eutectic points (15 and 75 mole% of CPB). This was explained by some component fluctuation originating in the inversion of solvent-solute relationships at the eutectic mixing ratio.     

Copper(I) 1,2,3-triazol-5-ylidene complexes as efficient catalysts for click reactions of azides with alkynes

Complexes of copper with 1,4-diphenyl, 1,4-dimesityl, and 1-(2,6-diisopropylphenyl)-4-(3,5-xylyl)-1,2,3-triazol-5-ylidene (abnormal NHC = N-heterocyclic carbene) were prepared by consecutive treatment of the corresponding azolium salts with silver oxide and copper chloride. The new CuCl(aNHC) complexes efficiently catalyzed click reactions of azides with alkynes to give 1,4-substituted 1,2,3-triazoles in excellent yields at room temperature with short reaction times. CuCl(TPh) was particularly effective for the reaction between sterically hindered azides and alkynes.     

Photofragmentation of the K-shell excited perfluorocyclobutane: anisotropies in the fragments and breakdown pathways

Total ion yield spectrum of perfluorocyclobutane (c-C(4)F(8)) has been measured in the C and F K-shell excitation regions. The peak assignments are presented based on angle-resolved photofragment ion mass spectrometry. The peaks at 291.34 and 688.5 eV are found to come from the transitions from the C 1s and the F 1s to the lowest unoccupied b(2)σ(CF)* orbital, respectively. A photoelectron-photoion-photoion coincidence spectrum is acquired at 700.1 eV for clarifying the breakdown pathways of c-C(4)F(8)(2+). Two series of the pathways are identified; fission of F atom(s) followed by charge separation and elimination of CF(2) or CF(3) followed by charge separation.     

Complete Fermi surface in BaFe2As2 observed via Shubnikov-de Haas oscillation measurements on detwinned single crystals

We show that the Fermi surface (FS) in the antiferromagnetic phase of BaFe(2)As(2) is composed of one hole and two electron pockets, all of which are three dimensional and closed, in sharp contrast to the FS observed by angle-resolved photoemission spectroscopy. Considerations on the carrier compensation and Sommerfeld coefficient rule out existence of unobserved FS pockets of significant sizes. A standard band structure calculation reasonably accounts for the observed FS, despite the overestimated ordered moment. The mass enhancement, the ratio of the effective mass to the band mass, is 2-3.     

Flow of a single magnetic vortex in a submicron-size superconducting Al disk controlled by radio-frequency currents

We report the first observation of a single-vortex flow in a mesoscopic superconductor. A flow of a single vortex is successfully controlled by an rf current superimposed on a dc current, evidence of which is provided by voltage steps in current-voltage (I-V) characteristics. Irrespective of the number of vortices confined to the disk, we unambiguously observe that when a single vortex inside the disk is driven out of the disk, another vortex enters the disk similarly to two balls colliding in billiards: only one vortex passes through the Al disk at the same time in mesoscopic systems.     

Imperfection errors in glass block faraday effect current sensor

Theoretical analysis of measurement errors caused by the imperfection of the sensing optical loop in a glass block Faraday effect current sensor has been presented. The experimental results with the fabricated sensor which was designed to achieve a closed homogeneous and isotropic optical path show the importance of the perfectly isotropic and closed loop, in accordance with the theoretical consideration.     

Formation of defect structures in Au-polysilane interfaces probed by low energy positron beams

Formation and accumulation of defect structures at interfaces between polysilanes and vacuum-evaporated gold (Au) electrodes are discussed quantitatively by low energy positron annihilation spectroscopy. The size distribution of the defects at the interface is analyzed based on the values of ortho-positronium (o-Ps) lifetime (τ₃), and no effect of the evaporation process is observed in the polymer films. The intensity of o-Ps (I₃) indicates no considerable change before and after Au evaporation on dialkyl-substituted polysilanes, however, the values of I₃ is increased ∼20% in phenyl-substituted polysilane (PMPS) by the evaporation. The I₃ dependence on incident positron energy suggests the formation of the defects not only at an Au-PMPS interface but also in PMPS bulk phase as deep as 400 nm from the interface. Phenyl ring dissociation from the polymer backbone will play a significant role in the selective formation of the defects in PMPS. This is the first report on the direct measurement of defect structures at conjugated polymer-metal interface with non-destructive way, implying that electrode fabrication by vacuum evaporation affects the solid state structure of polymers.