59Co-NMR Knight Shift of the Superconducting NaxCoO2.yH2O

Layered Co oxide NaxCoO2.yH2O with the superconducting transition temperature Tc =4.5 K has been studied by 59Co-NMR. The Knight shift K estimated from the observed spectra for powder sample exhibits almost temperature(T)-independent behavior above Tc and decreases with decreasing T below Tc. This result and the existence of the coherence peak in the spin-lattice-relaxation-rate versus T curve reported by the present authors indicate, naively speaking, that the singlet order parameter with s-wave symmetry is realized in NaxCoO2.yH2O. Differences of the observed behaviors between the spectra of the non-aligned sample and the one aligned in epoxy adhesive by applying the external magnetic field are discussed.Comment: 6 pages, 4 figures, submitted to J. Phys. Soc. Jp

Experimental demonstration of the time reversal Aharonov-Casher effect

We demonstrate the time reversal Aharonov-Casher (AC) effect in small arrays of mesoscopic semiconductor rings. By using an electrostatic gate we can control the spin precession rate and follow the AC phase over several interference periods. We show that we control the precession rate in two different gate voltage ranges; in the lower range the gate voltage dependence is strong and linear and in the higher range the dependence in almost an order of magnitude weaker. We also see the second harmonic of the AC interference, oscillating with half the period. We finally map the AC phase to the spin-orbit interaction parameter alpha and find it is consistent with Shubnikov-de Haas analysis.Comment: 4 pages, 6 figure

Developing spline based overset grid assembling approach and application to unsteady flow around a moving body

Overset or Chimera grid approach is one of methods to cope with complex geometries. A spline based overset grid assembling system has been developed. The sys- tem is based on structured grid approach and covers comprehensive features for overset assembling, i.e., grid generation, grid modification, and computing Receptor-Donor Con- nectivity (RDC) for overset interpolation. Ferguson spline curve is used to compute curves through grid points and cell centers for trimming grids and computing RDC robustly and accurately. Flow simulation around Kriso Container Ship(KCS) with jointed grids shows good continuity of flow field between the grids. The overset grid assembling is enhanced to unsteady problem as dynamic overset approach coupled with a solver which also has been developed in National Maritime Research Institute, Japan. Computed results for pitchup spheroid are compared with measured data and show good agreement in unsteady force acting on the spheroid. It is confirmed that the system has capability to simulate flow field around jointed grids and unsteady flow with dynamic overset assembling approach practically