Magnetic properties of diluted magnetic semiconductors: Quantum Monte Carlo approach

The magnetic correlation between magnetic impurities in semiconductors is investigated by performing the quantum Monte Carlo (QMC) simulation. The Anderson Hamiltonian with the realistic parameters obtained by the local density approximation (LDA) calculation is employed. The LDA calculation gives a dispersion of the host (GaAs) electron and the mixing energy between host and magnetic impurity (Mn). The mixing between host and impurity electrons generates the impurity bound state in the energy gap of semiconductors. The long range ferromagnetic coupling is observed when the Fermi energy locates between the band edge and the impurity bound state. The ferromagnetic coupling is enhanced by decreasing temperature.     

Canonical formulation of magnetic domain-wall motion

We revisit a long-standing problem concerning the inertial mass of a magnetic domain wall (DW) motion. Using constrained Hamiltonian formalism, we set up the macroscopic physical Hamiltonian describing the free-particle-like motion of the DW starting with the micromagnetic Lagrangian density.     

Synthesis of 2H‐Azirines by Iridium‐Catalyzed Decarboxylative Ring Contraction of Isoxazol‐5(4H)‐ones

A phosphine‐free iridium‐catalyzed reaction of isoxazol‐5(4H)‐ones (isoxazolones) has been developed, and affords 2H‐azirines through decarboxylation and ring contraction. This method provides an efficient and environmentally benign protocol which could replace the conventional approaches used to synthesize 2H‐azirines.     

Charge transport in the normal metal/diffusive ferromagnet/s-wave superconductor junctions

Charge transport in the normal metal/insulator/diffusive ferromagnet/insulator/s-wave superconductor (N/I/DF/I/S) junctions is studied for various situations solving the Usadel equation under the Nazarov's generalized boundary condition. Conductance of the junction is calculated by changing the magnitude of the resistance in DF, Thouless energy in DF, the exchange field in DF, the transparencies of the insulating barriers. We have found a new broad peak around zero voltage as well as zero bias conductance peak splitting and dip splitting.     

Positive working photoresists sensitive to visible light,II: poly{2-arylpropyl-2 and bis(p-methoxyphenyl)methyl methacrylates}

Acid-labile polymers of methacrylates of 2-(p-substituted phenyl)propanol-2 and bis(p-methoxyphenyl)methanol were evaluated as visible light sensitive positive-type resists. The chemistry to form images is based on the cleavage of esters catalysed by an acid generated by photodecomposition of diphenyliodonium hexafluorophosphate sensitized by 2-benzoyl-3-(p-dimethylaminophenyl)-2-propenenitrile. A copolymer of bis(p-methoxyphenyl)methyl methacrylate-phenyl methacrylate exhibited a high photospeed upon exposure to 488 nm light when coupled with the iodonium salt and the dye, and was applicable to relief holography.     

Iridium complex-catalyzed [2+2+2] cycloaddition of alpha,omega-diynes with monoynes and monoenes

[reaction: see text] [Ir(cod)Cl]2/DPPE was found to be a new catalyst for the cycloaddition of alpha,omega-diynes with monoynes to give polysubstituted benzene derivatives in high yields. Internal monoynes as well as terminal monoynes could be used. The reaction tolerates a broad range of functional groups such as alcohol, amine, alkene, ether, halogen, and nitrile. The reaction of 1,6-octadiyne derivatives with 1-alkynes gives ortho products and meta products. The regioselectivity could be controlled by the choice of ligand. The reaction with DPPE was meta selective, with meta selectivity of up to 82%. The reaction with DPPF was ortho selective, with ortho selectivity of up to 88%. We propose a mechanism to account for this regioselective cycloaddition. [Ir(cod)Cl](2)/DPPE also catalyzed the cycloaddition of alpha,omega-diynes with 2,5-dihydrofuran to give bicyclic cyclohexadiene derivatives. The reaction with 2,3-dihydrofuran and n-butyl vinyl ether gave benzene derivatives instead of cyclohexadiene derivatives. We also propose a mechanism to account for this novel aromatization that includes cleavage of the C-O bond.