26 research outputs found

    Magnon scattering and tunneling through localized states in magnetic tunnel junctions

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    Spin-dependent tunnel junctions with Co75Fe25 electrodes and a Fe50Mn50 pinning layer were fabricated with tunneling magnetoresistance of about 20% at room temperature. The Al2O3 barriers were formed by ultra-violet light assisted oxidation. The resistance x area (RxA) product was about 375 kOmega mum(2) in the parallel alignment of the magnetizations. The effect of barrier impurities has been investigated via tunneling conductance as a function of temperature and bias voltage for as-deposited and annealed samples. The spin wave parameter alpha was determined to be 3.06x10(-5) and 2.03x10(-5) K-3/2 before and after annealing, respectively. The improved barrier properties after annealing are explained by inelastic hopping via several localized states and reduced magnon scattering. We propose a qualitative model of the barrier homogenization during annealing which supports former Rutherford backscattering and x-ray photoelectron spectroscopy studies. (C) 2002 American Institute of Physics

    Surface morphology for ion-beam sputtered Al layer with varying sputtering conditions

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    We study the growth morphology of thin macrostructure films which is known to be largely affected by the deposition conditions as thin film nucleation and formation is dependent on the kinetic energy and chemical free energy of the atoms. The ion-beam sputtering technique used for depositing thin layers is due to the advantage over other techniques, e.g. the independent control of many process parameters, such as the pressure and/or the energy of the ion-beam and the substrate temperature. Therefore, the dependence of various sputtering parameters such as: (i) sputtering pressure and/or the rate of deposition and (ii) the effect of substrate temperature on the growth has been studied by depositing a single layer of Al. The variations show some interesting dependencies on the structural parameters for the Al layer deposited which has been understood in terms of thin film growth and nucleation theory. (c) 2005 Elsevier B.V. All rights reserved

    Automatic Creation of Flexible Antropomorphic Models for 3D Videoconferencing

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    This contribution describes the automatic creation of highly realistic flexible 3D models of participants for distributed 3D videoconferencing systems. The proposed technique uses a flexible mesh template surrounding an interior skeleton structure, which is based on a simplified human skeleton. The vertices of this template are arranged in rigid rings along the bones of the skeleton. Using 3D data obtained by a shape from silhouette approach the size and shape of the mesh template is adapted to the real person. Texture mapping of the adapted mesh using real camera images leads to a natural impression. The mesh organization in rigid rings allows an efficient surface deformation according to the skeleton movements. Once the resulting model is transmitted, it can be animated subsequently using the simple parameter set of the interior skeleton structure. Results obtained with real image data confirm the eligibility of the animated person models in terms of realism and efficiency for 3D vid..

    Automated Modelling of Real Human Faces for 3D Animation

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    This paper describes the automated creation of a textured face mask of a natural person suitable for realtime animation. A 3D surface polygon face mask is used. A set of muscles is defined to animate the mask. The mask is adapted to a real person using 3D surface data from a calibrated stereo sensor. Firstly, the facial features of the mask are aligned to the 3D data by scaling the mask. Secondly, a local shape adaptation moves the mask vertices along their surface normals to be coplanar with the measured 3D surface. The adapted mask is textured from one of the stereo images yielding a highly realistic impression. The predefined muscles are used to animate the textured mask. Index terms - Face Modeling, Shape from Stereo, 3D Adaptation, Facial Animation 1. Introduction The modelling of realistic looking human faces and facial expressions has been a challenge to computer scientists for many years. Today, the hardware processing power permits real-time modelling of human faces even on..
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