No abstract

A sensitive and simple optical method for detecting the cantilever deflection in atomic force microscopy is described. The method was incorporated in an atomic force microscope, and imaging and force measurements, in ultrahigh vacuum, were successfully performed.

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An atomic force microscope capable of measuring, simultaneously yet separately, lateral (‘‘frictional’’) and normal forces is described. A direction-dependent feature, absent in topological images, is found when scanning stepped surfaces of NaCl (001) in ultrahigh vacuum. A simple model is presented to account for this observation.

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We describe the voltage-current characteristics of YBa2Cu3O7−δ epitaxial films within the flux creep model in a manner consistent with the resistive transition behavior. The magnitude of the activation energy, and its temperature and magnetic field dependences, are readily derived from the experimentally observed power law characteristics and show a (1−T/Tc)3/2 type of behavior near Tc. The activation energy is a nonlinear function of the current density and it enables the determination of the shape of the flux line potential well.

No abstract

We report the observation of macroscopic collective behavior in a nemat.ic liquid crystal doped with well dispersed magnetic grains. This behavior is manifested as a uniform molecular orientational distortion of the entire doped matrix upon the application of external magnetic fields as low as