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Displaying 451 - 475 of 1560

Disorder effects on the intrinsic nonlinear current density in YBa2Cu3O7

June 1, 2007
Author(s)
Brian M. Andersen, James Booth, P.J. Hirschfeld
We present harmonic generation measurements of the intrinsic nonlinear current density j2 of (YBCO) films at temperatures close the Tc. Experiments on a range of different quality samples allow us to extract the dependence of j2 on the penetration depth of

Dielectric polarization evolution equations and relaxation times

May 25, 2007
Author(s)
James R. Baker-Jarvis, Billy F. Riddle, Michael D. Janezic
In this paper we develop a model that can describe broadband dielectric response, and includes frequency-dependent loss and the effects of the local electric field. The model is based on a correlation-function approach that we previously developed using

Thirty Years in Electromagnetic Compatibility: Projects and Colleagues

May 1, 2007
Author(s)
David A. Hill
Abstract?This paper is a review of my thirty years in electromagnetic compatibility and the projects and colleagues with whom I have had the pleasure of working. The field has evolved considerably over that time (and this evolution is continuing), and my

Complex Permittivity Measurements at Millimeter Wave Frequencies

April 23, 2007
Author(s)
Billy F. Riddle, Michael D. Janezic
Contemporary circuit designers are requiring larger bandwidths from microsystems to accomodate the ever-increasing demand for denser content. The electrical performance of these microsystems is intrisically related to the electromagnetic properties of the

Low-field current-hysteretic oscillations in spin-transfer nanocontacts

April 19, 2007
Author(s)
Matthew Pufall, William Rippard, Michael Schneider, Stephen E. Russek
We have measured spin-transfer-driven, large-amplitude, current-hysteretic, low frequency (less than or equal to} 500 MHz), narrowband oscillations in nanocontacts made to spin valve structures. The oscillations occur in zero field, persist up to 5 mT for

On-Wafer Measurement of Transistor Noise Parameters at NIST

April 1, 2007
Author(s)
James P. Randa, Dave K. Walker
NIST has developed the capability to measure noise parameters on a wafer int he 1-12.4 GHz range. We describe the measurement method and the uncertainty analysis and present results of measurements on a very poorly matched transistor.

Metrology for High-Frequency Nanoelectronics

March 27, 2007
Author(s)
Thomas Mitchell (Mitch) Wallis, Atif A. Imtiaz, Hans Nembach, Paul Rice, Pavel Kabos
Two metrological tools for high frequency measurements of nanoscale systems are described: (i) tow/N-port analysis of nanoscale devices as well as (ii) near-field scanning microwave microscopy (NSMM) for materials characterization. Calibrated two/N-port

Broadband Electrical Characterization of Multiwalled Carbon Nanotubes and Contacts

March 22, 2007
Author(s)
Thomas M. Wallis, Stephen E. Russek, Pavel Kabos, Paul Rice
The electrical response of an individual multiwalled carbon nanotube (MWNT) and its contacts, welded to a coplanar waveguide (CPW), was measured up to 24 GHz using a technique that removes environment effects. This is the first time MWNT contact effects

Thermal effects on the critical current of spin torque switching in spin valve nanopillars

February 28, 2007
Author(s)
Michael Schneider, Matthew Pufall, William Rippard, Stephen E. Russek, Jordan A. Katine
In spin valve nanopillars, temperature affects the spin torque reversal of the free magnetic layer. The authors compare values of zero temperature critical switching current I c0 extrapolated from room temperature pulsed current switching measurements to

Observation of Faraday waves in a Bose-Einstein condensate

February 26, 2007
Author(s)
Peter Engels, Colin Atherton, Mark Hoefer
Faraday waves in a cigar-shaped Bose-Einstein condensate are created. It is shown that periodically modulating the transverse confinement, and thus the nonlinear interactions in the BEC, excites small amplitude longitudinal oscillations through a

Standards Development for Wireless Communications for Urban Search and Rescue Robots

February 26, 2007
Author(s)
Kate Remley, Galen H. Koepke, Elena R. Messina, Adam S. Jacoff, George Hough
To gather data in support of standards development for urban search and rescue robots, NIST is conducting a series of field tests to quantify the functionality and performance of various candidate robots. During these tests, manufacturers bring robots that

Leakage Effects on Microwave Power Measurements

January 26, 2007
Author(s)
Ronald A. Ginley, Denis X. LeGolvan, Ann F. Monke
Microwave power measurements are used to support almost every every segment of the microwave electronics industry. It is very important for these measurements to be as accurate as possible. Recently we have found several different problems that affect

TEM Horn Antenna Design Principles

January 23, 2007
Author(s)
Chriss A. Grosvenor, Robert T. Johnk, David R. Novotny, Nino Canales, Benjamin Davis, Jason Veneman
The National Institute of Standards and Technology has developed several ultra-wideband, TEM Horn antennas with phase linearity, short impulse duration, and a near constant antenna factor. These are time-domain antennas used to measure impulsive fields

Origins of switching field distributions in perpendicular magnetic nanodot arrays

January 19, 2007
Author(s)
Justin Shaw, William Rippard, Stephen E. Russek, Tim Reith, Charles M. Falco
We studied the reversal properties of perpendicularly magnetized Co/Pd nanodots from 100 to 50 nm in diameter fabricated using electron beam lithography. Polycrystalline Co/Pd multilayers show considerable differences in the switching field distribution
Displaying 451 - 475 of 1560