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Tunneling Resistance (tunneling + resistance)

Distribution by Scientific Domains

Physics and Astronomy	60%

Selected Abstracts

Highly Conductive Carbon Nanotube/Polymer Nanocomposites Achievable?

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2009
Xinxin Sun
Abstract Carbon nanotubes (NT) have attracted growing interest in recent years as a conducting filler in the development of conductive polymer composites. However, most of experimental results show that the conductivity of NT/polymer composites is significantly lower than expected. Can NTs be an effective conductive filler for improving the electrical conductivity of polymers? In order to answer this question, a continuum model was constructed by introducing effective tunneling conduction in a non-universal network for the prediction of electrical conductivity of NT/polymer composites. Based on this model, the effect of the microstructure of NT/polymer composites on conductivity was assessed particularly for NT/polyethylene, NT/polyimide, and NT/poly(vinyl alcohol) composites. NT contact resistance and tunneling resistance have significant influences on the conductivity. The effects of the potential barrier of polymer and the tortousity of single-walled NTs on the conductivity were also analyzed. NTs cannot be considered as a valuable conductive filler for the development of highly conductive polymer composites unless the contact and tunneling resistances are reduced significantly. [source]

Low frequency noise in Co/Al2O3,Si,/Py magnetic tunnel junctions

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2008
R. Guerrero
Abstract Low frequency noise and dynamic tunneling resistance have been studied in Co(80 Å)/Al2O3(12 Å)/Py(100 Å) magnetic tunnel junctions (MTJs) with and without asymmetric Si doping of the insulating barrier (Si , 1.8 Å). Variation of the dynamic resistance and tunneling resistance with Si doping and applied bias in these MTJs indicate a transition from the Si-doped regime to Si cluster formation above a , -layer thickness of about 1.2 Å, close to 1 monolayer coverage. The measurements show anomalously strong enhancements of the low frequency noise for Si thickness above 1.2 Å, mainly due to the appearance of random telegraph noise. A simple model, which considers suppression of Coulomb blockade in the array of Si dots, opening two-step tunnel channels, qualitatively explains the variation of both conductivity and noise with Si content. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Co2MnSi as full Heusler alloy ferromagnetic electrode in magnetic tunneling junctions

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2006
G. Reiss
Abstract The discoveries of antiferromagnetic coupling in Fe/Cr multilayers by Grünberg, the Giant MagnetoResistance by Fert and Grünberg and a large tunneling magnetoresistance at room temperature by Moodera have triggered enormous research on magnetic thin films and magnetoelectronic devices. Large opportunities are especially opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on an external magnetic field can be found. In order to obtain large magnetoresistance effects, materials with strongly spin polarized electron gas around the Fermi level have to be found. New materials with potentially 100% spin polarization will be discussed using the example of the full Heusler compound Co2MnSi. First, experimental aspects of the integration of this alloy in magnetic tunneling junctions will be addressed. With these junctions, we obtain up to 100% TMR at low temperature. The current status of this research will then be summarized with special regard to the complex diffusion mechanisms occurring in these devices and to the properties of the interfaces between the Heusler material and the insulator. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]