Theory of current-driven domain wall motion: spin transfer versus momentum transfer

A self-contained theory of the domain wall dynamics in ferromagnets under finite electric current is presented. The current has two effects: one is momentum transfer, which is proportional to the charge current and wall resistivity (rho(w)); the other is spin transfer, proportional to spin current. For thick walls, as in metallic wires, the latter dominates and the threshold current for wall motion is determined by the hard-axis magnetic anisotropy, except for the case of very strong pinning. For thin walls, as in nanocontacts and magnetic semiconductors, the momentum-transfer effect dominates, and the threshold current is proportional to V(0)/rho(w), V0 being the pinning potential.     

Solving Three-Cluster OCM Equations in the Faddeev Formalism

Two different types of orthogonality condition models (OCM) are equivalently formulated in the Faddeev formalism. One is the OCM which uses pairwise orthogonality conditions for the relative motion of clusters, and the other is the one which uses the orthogonalizing pseudo-potential method. By constructing a redundancy-free T-matrix, one can exactly eliminate the redundant components of the total wave function for the harmonic-oscillator Pauli-forbidden states, without introducing any limiting procedure. As an example, a three--particle model interacting via the deep potential by Buck, Friedrich, and Wheatley is investigated.     

Ultra-hydrophobic fluorine polymer by Ar-ion bombardment

A study has been made of the improvement of the hydrophobicity of a fluorine-polymer (polytetra-fluorinethylene, PTFE) by Ar-ion bombardment. Ar-ion bombardment to PTFE) by Ar-ion bombardment. Ar-ion bombardment to PTFE sheets was carried out at the fluences ranging from 3.1x10(20) to 18.3x10(20) ions/m(2). The beam current densities were ranged from 1.25 to 7.5 A/m(2). The hydrophobicity of modified materials has been investigated by means of a sessile drop method of water. The roughness, morphology and structure of bombarded specimens have been estimated as a function of beam current density and acceleration energy. It was found that Ar-bombardment causes the contact angle of water to increase from the original value 103 to 170 degrees. The results indicate that Ar-bombardment at an optional condition results in the formation of ultrahydrdophobic surfaces. The effects of Ar-bombardment to hydrophobicity of PTFE are discussed with the relationship among roughness, morphology and chemical bonding states of the surfaces.     

A study of np annihilations around 0.65 GeV/c

$\text{n}\text{p}$ annihilations with ? 3 prongs with an incident antineutron momentum between 0.5 and 0.8 GeV/c are analysed. We present the topological branching ratios and cross sections, the resonance production rates and possible ?-ω interference effects.     

Evidence for the singlet-dimer ground state in an S = 1 antiferromagnetic bond alternating chain

Susceptibility, ESR, and magnetization measurements have been performed on single crystals of an S = 1 bond alternating chain compound: [Ni(333-tet) (mu-NO2)] (ClO4) (333-tet = N,N'-bis(3-aminopropyl)propane-1,3-diamine) and the compound doped with a small amount of Zn. We observed an anomalous angular dependence in the Zn-doped sample. These results are well explained by the model based on the valence-bond solid picture for the singlet-dimer phase. The picture implies that the free spins of S = 1 with a positive uniaxial single-ion anisotropy are induced at the edges of the chains without forming the singlet dimer.     

Adsorption behavior of natural anthocyanin dye on mesoporous silica

Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.     

Novikov homology,jump loci and Massey products

Let X be a finite CW complex, and ρ: π ₁(X) → GL(l, ?) a representation. Any cohomology class α ∈ H ¹(X, ?) gives rise to a deformation γ _t of ρ defined by γ _t (g) = ρ(g) exp(t〈α, g〉). We show that the cohomology of X with local coefficients γ _gen corresponding to the generic point of the curve γ is computable from a spectral sequence starting from H*(X, ρ). We compute the differentials of the spectral sequence in terms of the Massey products and show that the spectral sequence degenerates in case when X is a Kähler manifold and ρ is semi-simple. If α ∈ H ¹(X, ?) one associates to the triple (X, ρ, α) the twisted Novikov homology (a module over the Novikov ring). We show that the twisted Novikov Betti numbers equal the Betti numbers of X with coefficients in the local system γ _gen. We investigate the dependence of these numbers on α and prove that they are constant in the complement to a finite number of proper vector subspaces in H ¹(X, ?).     

A mild and efficient synthesis of a chiral pyridazinone derivative

We found a mild and efficient reaction condition for construction of a chiral 5-methyl-4,5-dihydropyridazin-3(2H)-one from a chiral β-methyl γ-ketocarboxylic acid via the corresponding acid hydrazide without racemization. Furthermore, we demonstrated that this two-step reaction can be attained by one-pot reaction. This method could be applied to various kinds of substrates because of the mild reaction conditions.     

Absorption spectra induced by photoexcitation and electrochemical doping in polythiophene

Changes of absorption spectra in a polythiophene film caused by photo- excitation and electrochemical doping are studied. The photoexcitation and the slight doping reveal that the formation of a shallow polaron is responsible to the carrier transport. The doping also induces a deep polaron which can explain the change of spectra upon doping.