The effect of surfaces on the tunneling density of states of an anisotropically paired superconductor

We present calculations of the tunneling density of states in an anisotropically paired superconductor for two different sample geometries: a semi-infinite system with a single specular wall, and a slab of finite thickness and infinite lateral extent. In both cases we are interested in the effects of surface pair breaking on the tunneling spectrum. We take the stable bulk phase to be of d_x ²–y² symmetry. Our calculations are performed within two different band structure environments: an isotropic cylindrical Fermi surface with a bulk order parameter of the form k _x ² –k _y ² , and a nontrivial tight-binding Fermi surface with the order parameter structure coming from an antiferromagnetic spin-fluctuation model. In each case we find additional structures in the energy spectrum coming from the surface layer. These structures are sensitive to the orientation of the surface with respect to the crystal lattice, and have their origins in the detailed form of the momentum and spatial dependence of the order parameter. By means of tunneling spectroscopy, one can obtain information on both the anisotropy of the energy gap, ¦(p)¦, as well as on the phase of the order parameter, (p) = ¦(p)¦ e^i(p).     

Superfluid3He-B in a realistic thin film. Gap and critical current

We examine³He-B confined to a thin film on a rough substrate with a freestanding upper surface by using quasiclassical techniques. First, the dependence of the gap on surface roughness, film width, and boundary condition formulation is examined in detail for the current-free state. The evaluation is conducted using both the Randomly Rippled Wall and the Thin Dirty Layer surface models in order to compare them. Second, the current bearing state for a submicron film resting on a rough substrate is calculated using the Thin Dirty Layer surface model. Several unusual and previously unreported features appear in both cases. Numerical estimates of the critical current densities are in favorable agreement with corresponding experiments.     

A compact thin-film-based all-pass device for the compensation of the in-band dispersion in FBG filters

Fiber Bragg grating (FBG)-based bandpass filters, while possessing close to ideal sharp rolloff characteristics, can suffer from a significant amount of in-band dispersion. Results concerning the compensation of the in-band dispersion of a typical 100-GHz FBG using two thin-film all-pass filters, each composed of two coupled-cavities packaged in a compact configuration, are presented. The total peak insertion loss of the compensation package is less than 2.5 dB.     

Deciphering professional codes of ethics

The author focuses chiefly on the Code of Professional Standards for the Practice of Public Relations, analyzing two specific aspects of this or any professional code: implicit and explicit attitudes toward the public and toward the truth. He argues that professionals confronted by ethical dilemmas in these areas should be able to, but usually cannot, find clear direction in the official code. He suggests that to function truly as a legitimizing document, the code must be expository, analytical, and evaluational, constructed according to six recommendations offered     

Interaction of a granular stream with an obstacle

We investigate numerically the interaction of a stream of granular particles with a resting obstacle in two dimensions. For the case of high stream velocity we find that the force acting on the obstacle is proportional to the square of the stream velocity, the density and the obstacle size. This behaviour is equivalent to that of non-interacting hard spheres. For low stream velocity a gap between the obstacle and the incoming stream particles appears which is filled with granular gas of high temperature and low density. As soon as the gap appears the force does not depend on the square of velocity of the stream but the dependency obeys another law.     

Texturvererbung und Transformation aus der austenitischen in die martensitische Phase bei streckbelasteten 18/8 CrNi-Rundstählen

Fasertexturen – Blechtexturen. Transformationsmechanismen fcc – hcp – bcc. Selektion der Gleit- und Scherrichtungen durch Textur und Zugspannung. Texturmessung mit Neutronenbeugung. Rekonstruktion der gemessenen bcc-Texturverteilung als Vererbung aus der fcc-Phase bei gleichzeitiger Verkippung der neugebildeten bcc-Kristallite durch weitere Verformung. Gemisch aus Nishiyama-Wasserman- und Kurdjumov-Sachs-Transformation mit jeweils zwei erlaubten Gleit- und Scherrichtungen.     

Photoinduced switching of the current through a single molecule: effects of surface plasmon excitations of the leads

The photoinduced switch of the current through a single molecule is studied theoretically by including plasmon excitations of the leads. A molecule weakly linked to two spherical nanoelectrodes is considered resulting in sequential charge transmission scheme. Taking the molecular charging energy (relative to the equilibrium lead chemical potential) to be comparable to the molecular excitation energy, an efficient current switch in a low voltage range becomes possible. A remarkable enhancement of the current is achieved due to simultaneous plasmon excitations in the electrodes. The behavior is explained by an increased molecular absorbance due to oscillator strength transfer from the electrode plasmon excitations and by a net excitation energy motion from the electrodes to the molecule.