Sawako Nakamae

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We directly measured curvature elasticity of dipalmitoylphosphatidylcholine multilamellar bilayers close to the chain-melting transition using the method of electric-field-induced bending deformation of the cylindrical tubes. The result shows that the bending modulus, kappa(c), decreases remarkably at temperatures close to the melting transition(More)
We report measurements of the in-plane thermal conductivity kappa of the stoichiometric underdoped cuprate YBa2Cu4O8 (Y124) below 1 K. kappa(T) is shown to follow a simple phononic T3 dependence at the lowest temperature T for both current directions, with a negligible linear quasiparticle contribution. This observation is in marked contrast with behavior(More)
We present an experimental study of magnetization in lambda-DNA in conjunction with structural measurements. The results show the surprising interplay between the molecular structures and their magnetic property. In the B-DNA state, lambda-DNA exhibits paramagnetic behavior below 20 K that is nonlinear in an applied magnetic field whereas, in the A-DNA(More)
We present the experimental observation of the fluctuation-dissipation theorem violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin-glass phase. The magnetic noise is measured with a two-dimension electron gas Hall probe and compared to the out of phase ac susceptibility of the same ferrofluid. For "intermediate"(More)
The Seebeck coefficients of the nonaqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide, and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol, and ethylene-glycol are measured in a temperature range from T = 30 °C to T = 45 °C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for(More)
We report on zero field cooled magnetization relaxation experiments on a concentrated frozen ferrofluid exhibiting a low temperature superspin glass transition. With a method initially developed for spin glasses, we investigate the field dependence of the relaxations that take place after different aging times. We extract the typical number of correlated(More)
Interacting magnetic nanoparticles display a wide variety of magnetic behaviors that are now being gathered in the emerging field of ‘supermagnetism.’ We have investigated how the outof-equilibrium dynamics in the disordered superspin glass (SSG) state of a frozen ferrofluid sample is affected by texturation. Via magnetization relaxation experiments at low(More)
The application of a temperature difference (∆T) across a solid conductor causes mobile charge carriers to diffuse from hot to cold regions, giving rise to a thermoelectric voltage ∆V=-Se. ∆T. The prefactor Se is called the thermopower or Seebeck coefficient which describes how electrical energy can be generated from the thermal energy. The great majority(More)
The effect of magnetic anisotropy-axis alignment of individual nanoparticles on the collective aging behavior in the superspin glass state of a frozen ferrofluid has been investigated. The ferrofluid studied here consists of maghemite nanoparticles (γ-Fe2O3, mean diameter = 8.6 nm) dispersed in glycerin at a volume fraction of ~15%. The low temperature(More)
The Seebeck and Soret coefficients of ionically stabilized suspension of maghemite nanoparticles in dimethyl sulfoxide are experimentally studied as a function of nanoparticle volume fraction. In the presence of a temperature gradient, the charged colloidal nanoparticles experience both thermal drift due to their interactions with the solvent and electric(More)