A Theoretical Study on Spin-Dependent Transport of "Ferromagnet/Carbon Nanotube Encapsulating Magnetic Atoms/Ferromagnet" Junctions with 4-Valued Conductances

As a novel function of ferromagnet (FM)/spacer/FM junctions, we theoretically investigate multiple-valued (or multi-level) cell property, which is in principle realized by sensing conductances of four states recorded with magnetization configurations of two FMs; (up,up), (up,down), (down,up), (down,down). In order to sense all the states, 4-valued conductances corresponding to the respective states are necessary. We previously proposed that 4-valued conductances are obtained in FM1/spin-polarized spacer (SPS)/FM2 junctions, where FM1 and FM2 have different spin polarizations, and the spacer depends on spin [J. Phys.: Condens. Matter 15, 8797 (2003)]. In this paper, an ideal SPS is considered as a single-wall armchair carbon nanotube encapsulating magnetic atoms, where the nanotube shows on-resonance or off-resonance at the Fermi level according to its length. The magnitude of the obtained 4-valued conductances has an opposite order between the on-resonant nanotube and the off-resonant one, and this property can be understood by considering electronic states of the nanotube. Also, the magnetoresistance ratio between (up,up) and (down,down) can be larger than the conventional one between parallel and anti-parallel configurations.Comment: 10 pages, 4 figures, accepted for publication in J. Phys.: Condens. Matte

Agglomerate-free BaTiO3 particles by salt-assisted spray pyrolysis

Optimum conditions for the synthesis of nonagglomerated BaTiO3 particles by salt-assisted spray pyrolysis (SASP) were investigated. The effect of particle residence time in the reactor and salt concentration on the crystallinity and surface morphology of BaTiO3 was examined by x-ray diffraction and scanning electron microscopy. Mixtures of a metal chloride or nitrate salt, dissolved in aqueous precursor solutions, were sprayed by an ultrasonic atomizer into a five-zone hot-wall reactor. By increasing the salt concentration or the particle residence time in the hot zone, the primary particle size was increased, and its surface texture was improved compared to BaTiO3 particles prepared by conventional spray pyrolysis. The SASP-prepared BaTiO3 crystal was transformed from cubic to tetragonal by simply increasing the salt concentration at constant temperature and residence time. Further thermal treatments such as calcination or annealing are not necessary to obtain nonagglomerated tetragonal BaTiO3 (200-500 nm) particles with a narrow size distribution. Increasing the carrier gas flow rate and decreasing the residence time in the hot zone resulted in cubic BaTiO3 particles about 20 nm in diamete

スパッタ ホウ デ ツクッタ テツ ハクマク

Iron films deposited on glass substrates at normal incidence by sputtering were investigated. The substrate temperature ranged from room temperature to 300℃ and the argon gas pressures during deposition were 8, 10 and 20Pa. The incident power was varied from 40 to 200W. Results obtained are as follows. (1)With increasing the substrate temperature, the sticking coefficient of iron deposit decreases. This dependence differs from that of evaporated films. (2)The packing density is high in the films prepared at not only high but also low substrate temperatures. (3)With increasing argon gas pressure, gaps between crystallites become large. (4)The films consists of columnar grains and exhibits a crystallographic preferred orientation

Separation and determination of a trace amount of lithium as its thenoyltrifluoroacetone complex with 12-crown-4 by means of synergic extraction and flame photometry

A new method for the separation and determination of a trace amount of lithium in ppb∼ppm level in water as its thenoyltrifluoroacetone (TTA) complex with 12-crown-4 (12C4) has been established by means of synergic extraction and back extraction combined with flame photometry. The effect of various factors (pH, solvent, reagent concentration, shaking time, preconcentration factor, and foreign ions etc.) on the extraction and back extraction of lithium has been investigated. Here the lithium TTA chelate in o-dichlorobenzene forms stable adducts with 12C4 (LiTTA-n12C4, n=0∼2); the stability constants (β n) of the adducts determined by means of curve fitting method being βi=4.46 and β 2=6.45. The amount of lithium in sodium chloride of guaranteed reagent was found to be 9.5 -0.2 ppb by means of the proposed method. © 1991, The Japan Society for Analytical Chemistry. All rights reserved

The characteristics of Bi-2223/Ag conductor for high field application

For the development of high magnetic field application using high temperature superconductor (HTS), Bi-2223/Ag tape is one of the promising materials because of its high current capacity and upper critical field. However, Bi-2223/Ag tape shows very strong anisotropy and significant deterioration of critical current in the magnetic field. To explore the possibility of HTS in high field applications, we evaluated the critical current and index value of Bi-2223/Ag conductor in high magnetic field. The Bi-2223/Ag tape was characterized as a function of increasing and decreasing field. The temperature dependence was also examined lower than 4.2 K. All measurements were carried out with hybrid magnet system up to 30 T and the experimental results are reported

Agglomerate-free BaTiO3 Particles by Salt-Assisted Spray Pyrolysis

ISSN:0884-2914ISSN:2044-532

Effect of Pd Seed Layer on Magnetic Anisotropy in Co Films Evaporated at Oblique Incidence

The effect of Pd seed layer on the magnetic anisotropy in Co films evaporated at oblique incidence was investigated. The thickness of Pd was 500Å and that of Co was varied from 100 to 600Å. The substrate temperatures were -60, -30 and 20℃. Negatively large anisotropy of the squareness ratio appeared in the films prepared at low substrate temperatures -60 and -30℃ thought the anisotropy of the reflection coefficient and the magnetic anisotropy field were positive. The degree of the c-axis orientation perpendicular to the incidence plane seems to be a little large than that of parallel one. From these results, it is considered that the positive in-plane magnetic anisotropy may originate from the shape anisotropy of the columnar grains and/or magnetocrystalline anisotropy, and the anisotropy of the squareness ratio does not reflect the in-place magnetic anisotropy. In the films with negatively large anisotropy of the squareness ratio, large coercive force perpendicular to the film plane appeared. The MH loop in those films can be explained to be superposition of two loops with small and large coercive forces. We consider that the coercive force of under Co layer is small and that of over Co layer large