Tohoku University

About: Tohoku University is a education organization based out in Sendai, Japan. It is known for research contribution in the topics: Magnetization & Population. The organization has 72116 authors who have published 170791 publications receiving 3941714 citations. The organization is also known as: Tōhoku daigaku.

Self-assembly of a silica–surfactant nanocomposite in a porous alumina membrane

Abstract: A mesoporous membrane composed of nanochannels with a uniform diameter has a potential use for precise size-exclusive separation of molecules. Here, we report a novel method to form a hybrid membrane composed of silica-surfactant nanocomposite and a porous alumina membrane, by which size-selective transport of molecules across the membrane becomes possible. The nanocomposite formed inside each columnar alumina pore was an assembly of surfactant-templated silica-nanochannels with a channel diameter of 3.4 nm; the channel direction being predominantly oriented along the wall of the columnar alumina pore. Molecules could be transported across the membrane including the silica-surfactant nanocomposite with a capability of nanometre-order size-exclusive separation. Our proposed membrane system has a potential use not only for separation science, but also catalysis and chip technologies.

Observation of B̄0 → D(*)0 pp̄

Abstract: The B meson decay modes B → Dpp and B → D*pp have been studied using 29.4 fb - 1 of data collected with the Belle detector at KEKB. The B 0 → D 0 pp and B 0 → D* 0 pp decays have been observed for the first time with branching fractions B(B 0 → D 0 pp) = (1.18 ′ 0.15 ′ 0.16) X 10 - 4 and B(B 0 → D* 0 pp) = (1.20 + 0 . 3 3 - 0 . 2 9 ′ 0.21) X 10 - 4 . No signal has been found for the B + → D + pp and B + → D* + pp decay modes, and the corresponding upper limits at 90% C.L. are presented.

Effect of spin diffusion on Gilbert damping for a very thin permalloy layer in Cu/permalloy/Cu/Pt films

Abstract: Ferromagnetic resonance (FMR) was measured for Cu/permalloy (Py) (20, 30, 40 \AA{})/Cu ${(d}_{\mathrm{Cu}})/\mathrm{Pt}$ (0, 50 \AA{}) films with various ${d}_{\mathrm{Cu}}$ to clarify the effect of spin diffusion driven by the precession of magnetization on Gilbert damping. The peak-to-peak linewidth $\ensuremath{\Delta}{H}_{\mathrm{pp}}$ of the FMR spectra for Cu/Py/Cu/Pt films was very large at ${d}_{\mathrm{Cu}}=0\mathrm{\AA{}},$ and decreased remarkably at ${d}_{\mathrm{Cu}}=30\mathrm{\AA{}}.$ Above ${d}_{\mathrm{Cu}}=30\mathrm{\AA{}},$ it decreased gradually with increasing ${d}_{\mathrm{Cu}}$ in the anomalously wide range of ${d}_{\mathrm{Cu}}.$ The out-of-plane angular dependence of the FMR of Cu/Py(30 \AA{})/Cu ${(d}_{\mathrm{Cu}})/\mathrm{Pt}$ (0, 50 \AA{}) films was measured and analyzed using a Landau-Lifshitz-Gilbert equation that took into account the local variation of the effective demagnetizing field. The Gilbert damping coefficient G obtained from the analysis for Cu/Py/Cu/Pt films was about twice as large as that for Cu/Py/Cu films even at ${d}_{\mathrm{Cu}}=100\mathrm{\AA{}}$ and decreased gradually as ${d}_{\mathrm{Cu}}$ increased. At ${d}_{\mathrm{Cu}}=2000--3000\mathrm{\AA{}},$ G for Cu/Py/Cu/Pt and Cu/Py/Cu films has the same value. We discussed the influence of spin diffusion driven by the precession of magnetization in FMR on G using a previously proposed model. The calculated G vs ${d}_{\mathrm{Cu}}$ fitted well to the experimental one, and the other features of the experimental results are well explained by the model.

Ferrous Polycrystalline Shape-Memory Alloy Showing Huge Superelasticity

Abstract: Shape-memory alloys, such as Ni-Ti and Cu-Zn-Al, show a large reversible strain of more than several percent due to superelasticity. In particular, the Ni-Ti-based alloy, which exhibits some ductility and excellent superelastic strain, is the only superelastic material available for practical applications at present. We herein describe a ferrous polycrystalline, high-strength, shape-memory alloy exhibiting a superelastic strain of more than 13%, with a tensile strength above 1 gigapascal, which is almost twice the maximum superelastic strain obtained in the Ni-Ti alloys. Furthermore, this ferrous alloy has a very large damping capacity and exhibits a large reversible change in magnetization during loading and unloading. This ferrous shape-memory alloy has great potential as a high-damping and sensor material.