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Displaying 476 - 500 of 1560

Spin Torque for Dummies

January 6, 2007
Author(s)
Thomas J. Silva
I will present a stripped down presentation on the fundamental mechanisms that give rise to spin torque effects. This presentation will assume the audience has little or no background in this fascinating and rapidly expanding field. We will start with an

Complex permittivity measurements of planar building materials using a UWB free-field antenna measurement system

January 1, 2007
Author(s)
Ben N. Davis, Chriss A. Grosvenor, Robert T. Johnk, David R. Novotny, James R. Baker-Jarvis, Michael D. Janezic
Building materials are often incorporated into complex, multi-layer macrostructures that are simply not amenable to measurements using coax or waveguide sample holders. In response to this, an ultra-wideband free-field measurement system has been developed

Electromagnetics Division: Programs, Activities, and Accomplishments

January 1, 2007
Author(s)
Ronald B. Goldfarb
The Electromagnetics Division is a critical national resource for a wide range of customers. U.S. industry is the primary customer both for the division's measurement services and for technical support on the test and measurement methodology necessary for

Manipulation of magnetic particles by patterned arrays of magnetic spin-valve traps

December 20, 2006
Author(s)
Elizabeth Mirowksi, John M. Moreland, Stephen E. Russek, Michael J. Donahue
A novel magnetic for microfluidic manipulation of magnetic particles is discussed. The particles are confined by an array of magnetic spin valves with bistable ferromagnetic "ON" and antiferromagnetic "OFF" net magnetization states. The switchable fringing

Magnetic Resonance in an Atomic Vapor Excited by a Mechanical Resonator

December 1, 2006
Author(s)
Ying-Ju Wang, Matthew Eardley, Svenja A. Knappe, John M. Moreland, Leo W. Hollberg, John Kitching
We demonstrate a direct resonant interaction between the mechanical motion of a mesoscopic resonator and the spin degrees of freedom of a sample of neutral atoms in the gas phase. This couplin, mediated by a magnetic particle attached to the tip of the

Terminology for High-Speed Sampling-Oscilloscope Calibration

December 1, 2006
Author(s)
Dylan Williams, Tracy S. Clement, Paul D. Hale, Andrew Dienstfrey
We discuss procedures for calibrating high-speed sampling oscilloscopes at the National Institute of Standards and Technology, and the terminology associated with those calibrations. The discussion clarifies not only the calibration procedures, but how to

Dynamic Lorentz Microscopy of Micromagnetic Structure in Magnetic Tunnel Junctions

November 20, 2006
Author(s)
Justin Shaw, R.H. Geiss, Stephen E. Russek
Lorentz microscopy was used to study the micromagnetic structure and magnetization reversal in magnetic tunnel junctions (MTJs) fabricated with different processing conditions including a preoxidation process. The authors find that the free layer in a MTJ

Low Magnetic Moment PIN Diodes for High Field MRI Surface Coils

November 8, 2006
Author(s)
Pavel Voskoboynik, Ronald D. Joos, W E. Doherty, Ronald B. Goldfarb
Positive-intrinsic-negative (PIN) silicon diodes are commonly used in magnetic resonance imaging (MRI) coils to perform active or passive blocking and detuning, or to disable circuit functions. However, diode packages with large magnetic moments are known

On the Use of Reverberation Chambers to Simulate a Controllable Rician Radio Environment for the Testing of Wireless Devices.

November 1, 2006
Author(s)
Christopher L. Holloway, David A. Hill, John M. Ladbury, Perry F. Wilson, Galen H. Koepke, Jason Coder
With the proliferation of wireless devices in recent years, there is a growing need to test the operation and functionality of these various devices in different multipath radio propagation environments, ranging from a direct line-of-sight environment to a

Microwave Resonances in Nanogranular (Fe

October 2, 2006
Author(s)
Massimo Pasquale, Sergio Perero, Giorgio Bertotti, Pavel Kabos
We have analyzed the microwave behavior of soft nanogranular (Fe 0.7uCo 0.3u) 71uB 22uNi films with thickness of 136, 195 and 236 nm which present a dc relative permeability from 60 to 280, a resistivity of 8 to 9×10 7d Ω}m and a zero-field double

Experimental Techniques for Low-Temperature Measurements

October 1, 2006
Author(s)
John (Jack) W. Ekin
This textbook is written for the experimentalist starting in the laboratory -- beginning graduate students, industry measurement engineers, and materials scientists interested in learning how to design successful low-temperature (1 K to 300 K) measurement

Microcantilever Torque Magnetometry Study of Patterned Magnetic Films

October 1, 2006
Author(s)
L. Yuan, Lan Gao, R. Sabirianov, Sy-hwang Liou, Michelle Chabot, Dong-Hoon Min, John M. Moreland, Bao Shan Han
Microcantilever torque magnetometry (MTM) is a sensitive tool to measure small magnetization changes in the sample. In this paper, we investigated a process for preparing patterned magnetic films on cantilevers and studied the magnetic interactions of a

Phase Velocity in Resonant Structures

October 1, 2006
Author(s)
James R. Baker-Jarvis, Michael D. Janezic, Derik Love, Thomas Mitchell (Mitch) Wallis, Christopher L. Holloway, Pavel Kabos
In this paper we present a simple experimental procedure for studying the phase velocity behavior of a metafilm with tunable material properties. Using this approach we have studied the phase-velocity behavior of a metamaterial under different conditions

Propagation and Detection of Radio Signals Before, During, and After the Implosion of a Large Convention Center

October 1, 2006
Author(s)
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Catherine A. Remley, Susan A. Schima, M. McKinley, Robert T. Johnk
In this report, we investigate radio communications problems faced by emergency responders (firefighters and police) in disaster situations such as collapsed buildings. A fundamental challenge to communications into and out of large buildings is the strong

RFID-Assisted Indoor Localization and Communication for First Responders

October 1, 2006
Author(s)
Jeffrey R. Guerrieri, Michael H. Francis, Perry F. Wilson, Leonard E. Miller, Nelson Bryner, David Stroup, Luke Klien-Berndt
An indoor localization and communication project is described that proposes to use RFID (radio-frequency identification) tags, placed in the building beforehand, as navigation waypoints for an inertial navigation system carried by a first responder. RFID

Three-Antenna Extrapolation Gain Measurement System at Millimeter Wave Frequencies

October 1, 2006
Author(s)
Katherine MacReynolds, Jeffrey R. Guerrieri, Michael H. Francis, Douglas T. Tamura
This paper describes the new tabletop millimeter wave extrapolation range which will provide on-axis gain services up to 110GHz. A discussion of the extrapolation measurement method [1], as presented at the Antenna Measurements Techniques Association (AMTA

Einstein-de Haas effect in a NiFe film deposited on a microcantilever

September 18, 2006
Author(s)
Thomas Mitchell (Mitch) Wallis, John M. Moreland, Pavel Kabos
A new methods is presented for determining the magetomechanical ratio, g', in a thin ferromagnetic film deposited on a microcantilever via measurement of the Einstein-de Haas effect. An alternating magnetic field applied in the plane of the cantilever and
Displaying 476 - 500 of 1560