NMR relaxation time around a vortex in stripe superconductors

Site-dependent NMR relaxation time T1(r) is calculated in the vortex state using the Bogoliubov-de Gennes theory, taking account of possible "field-induced stripe" states in which the magnetism arises locally around a vortex core in d-wave superconductivity. The recently observed huge enhancement T-11(r) below T(c) at a core site in Tl2Ba2CuO6 is explained. The field-induced stripe picture explains consistently other relevant STM and neutron experiments.     

Thermodynamic properties of the mixture [x1,3-dioxane+(1-x) 1,4-dioxane] at the temperature 298.15 K

Excess enthalpies, excess heat capacities, excess volumes and sound velocities of the mixture of dioxane isomers, 1,3-dioxane and 1,4-dioxane, were measured. One of the isomers, 1,4-dioxane is considered as non-polar liquid and the other as polar liquid. Excess enthalpies are positive and small, less than 55 J mol^-1. Excess heat capacities are also very small and the curve is W-shaped, and the values are from 0.03 to -0.08 J mol^-1 K^-1. Excess volumes and excess isentropic compressibilities are small and positive, and less than 0.03 cm³ mol^-1 and 0.8 TPa^-1. This revised version was published online in August 2006 with corrections to the Cover Date.     

NMR observation of rattling phonons in the pyrochlore superconductor KOs2O6

We report nuclear magnetic resonance studies on the beta-pyrochlore oxide superconductor KOs2O6. The nuclear relaxation at the K sites is entirely caused by fluctuations of the electric field gradient, which we ascribe to highly anharmonic low frequency oscillation (rattling) of K ions. A phenomenological analysis shows a crossover from overdamped to underdamped behavior of the rattling phonons with decreasing temperature and its sudden sharpening below the superconducting transition temperature T(c). Suppression of the Hebel-Slichter peak in the relaxation rate at the O sites below T(c) also indicates strong electron-phonon coupling.