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Search Publications by: Robert D. McMichael (Fed)

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Displaying 101 - 125 of 160

Structural Effects in the Growth of Giant Magnetoresistance (GMR) Spin Valves

August 1, 2001
Author(s)
M. Menyhard, G. Zsolt, P J. Chen, Cedric J. Powell, Robert McMichael, William F. Egelhoff Jr.
Giant magnetoresistance (GMR) spin valves of the Co/Cu/Co type were grown on polycrystalline NiO substrates at three different temperatures. The GMR values and growth temperatures were: 14% for 150 K growth, 10% for 300 K growth, and 0% for 450 K growth

Surface and Interface Effects in the Growth of Giant Magnetoresistance Spin Valves for Ultrahigh-Density Data-Storage Applications

August 1, 2001
Author(s)
William F. Egelhoff Jr., P J. Chen, Cedric J. Powell, Robert D. McMichael, Mark D. Stiles
The current generation of hard disk drives use Giant Magnetoresistance (GMR) spin valves as the read-head because the GMR effect is currently the most sensitive way to detect magnetic fields at submicron length scales and data rates of {approximately equal

Switching Dynamics and Critical Behavior of Standard Problem No. 4

June 1, 2001
Author(s)
Robert McMichael, Michael J. Donahue, Donald G. Porter, J Eicke
We report switching dynamics for uMAG standard problem no. 4, a 500 nm x 125 nm x 3 nm rectangle of material with properties to mimic Permalloy. Siwtching dynamics are calculated for fields applied instantaneously to an initial s-state: Field 1 at 170o and

Large Anisotropy Via Oblique Sputtering of Ta Underlayers

May 1, 2001
Author(s)
John E. Bonevich, Robert D. McMichael, Chang H. Lee, P J. Chen, W Wyatt Miller, William F. Egelhoff Jr.
Anisotropy fields in excess of 120 KA/m (1500 Oe) have been produced in 3 nm to 5 nm thick polycrystalline films of Co by oblique sputtering of Ta underlayers. The unusually high anisotropy is magnetostatic in origin, and is induced by corrugations on the

Surface Oxidation as a Diffusion Barrier for Al Deposited on Ferromagnetic Metals

May 1, 2001
Author(s)
William F. Egelhoff Jr., P J. Chen, Robert D. McMichael, Cedric J. Powell, R Deslattes, F G. Serpa, Romel Gomez
We have used Grazing Incidence X-ray Reflectometry (GIXR) to study surface oxidation as a diffusion barrier for Al deposited on ferromagnetic metals (Co, Fe, Ni, and NiFe). Samples of the form SiO2 // 10nm X / 4nm Al and SiO2 // 10nm X/ 4nm Au with X = (Co

Abstracts for the MSEL Assessment Panel, March 2001

January 26, 2001
Author(s)
Leslie E. Smith, Alamgir Karim, Leonid A. Bendersky, C Lu, J J. Scott, Ichiro Takeuchi, Kathleen M. Flynn, Vinod K. Tewary, Davor Balzar, G A. Alers, Stephen E. Russek, Charles C. Han, Haonan Wang, William E. Wallace, Daniel A. Fischer, K Efimenko, Wen-Li Wu, Jan Genzer, Joseph C. Woicik, Thomas H. Gnaeupel-Herold, Henry J. Prask, Charles F. Majkrzak, Norman F. Berk, John G. Barker, Charles J. Glinka, Eric K. Lin, Ward L. Johnson, Paul R. Heyliger, David T. Read, R R. Keller, J Blendell, Grady S. White, Lin-Sien H. Lum, Eric J. Cockayne, Igor Levin, C E. Johnson, Maureen E. Williams, Gery R. Stafford, William J. Boettinger, Kil-Won Moon, Daniel Josell, Daniel Wheeler, Thomas P. Moffat, W H. Huber, Lee J. Richter, Clayton S. Yang, Robert D. Shull, R A. Fry, Robert D. McMichael, William F. Egelhoff Jr., Ursula R. Kattner, James A. Warren, Jonathan E. Guyer, Steven P. Mates, Stephen D. Ridder, Frank S. Biancaniello, D Basak, Jon C. Geist, Kalman D. Migler
Abstracts relating to research and development in the NIST Materials Science and Engineering Laboratory (MSEL) are presented for a poster session to be presented to the 2001 MSEL Assessment Panel.

Coercivity in Exchange-Bias Bilayers

January 18, 2001
Author(s)
Mark D. Stiles, Robert D. McMichael
Simulations of magnetic reversal in polycrystalline exchange-bias bilayers exhibit two contributions to the enhanced coercivity found in exchange-bias systems, one due to inhomogeneous reversal and and the other to irreversible transitions in the

Detection of Pinholes in Ultrathin Films by Magnetic Coupling

January 1, 2001
Author(s)
William F. Egelhoff Jr., L Gan, P J. Chen, Cedric J. Powell, Robert McMichael, R A. Fry
When two magnetic films are separated by a nonmagnetic film, pinholes in the nonmagnetic film can allow direct contact and, thereby, magnetic coupling between the two magnetic films. We have studied this coupling by having one of the magnetic films pinned

Magnetic Anisotropy and Thermal Stability of Ta-pinned Spin Valves

January 1, 2001
Author(s)
R A. Fry, Robert D. McMichael, John E. Bonevich, P J. Chen, William F. Egelhoff Jr., Chang H. Lee
It has recently been found that large uniaxial anisotropy fields in excess of 120 kA/m (1500 Oe) can be created in thin (3 nm to 5 nm) films of Co by obliquely sputtered Ta underlayers. This anisotropy can be used to pin the bottom film of a spin valve

Mathematics and Measurement

January 1, 2001
Author(s)
Ronald F. Boisvert, Michael J. Donahue, Daniel W. Lozier, Robert D. McMichael, Bert W. Rust
In this paper we describe the role that mathematics plays in measurement science at NIST. We first survey the history behind NIST's current work in this area, starting with the NBS Math Tables project of the 1930s. We then provide examples of more recent

Surface and interface effects in the growth of giant magnetoresistance spin valves for ultrahigh-density data-storage applications

January 1, 2001
Author(s)
William F. Egelhoff Jr., P J. Chen, Cedric J. Powell, Robert McMichael, Mark D. Stiles
The current generation of hard disk drives use Giant Magnetoresistance (GMR) spin valves as the read-head because the GMR effect is currently the most sensitive way to detect magnetic fields at submicron length scales and data rates of approximately equal}

Strong Anisotropy in Thin Magnetic Films Deposited on Obliquely Sputtered Ta Underlayers

November 1, 2000
Author(s)
Robert McMichael, C G. Lee, John E. Bonevich, P J. Chen, W. Wyatt Miller, William F. Egelhoff Jr.
Anisotropy fields in excess of 120 kA/m (1500 Oe) have been produced in 3-5 nm- thick polycrystalline films of Co by oblique sputtering of Ta underlayers. The unusually high anisotropy is magnetostatic in origin, and is induced by corrugations on the

Micromechanical Detectors for Ferromagnetic Resonance Spectroscopy

September 1, 2000
Author(s)
John M. Moreland, Pavel Kabos, Albrecht Jander, M. Loehndorf, Robert McMichael, C G. Lee
We demonstrate micromechanical detection of ferromagnetic resonance (FMR) in thin magnetic films. FMR spectroscopy is performed on nanometer scale samples integrated with a micromachined silicon cantilever. We present several techniques by which the FMR

Ferromagnetic Resonance Spectroscopy with a Micromechanical Calorimeter Sensor

August 1, 2000
Author(s)
John M. Moreland, M. Loehndorf, Pavel Kabos, Robert McMichael
We describe a new type of ferromagnetic resonance (FMR) spectroscopy that is based on a calorimeter sensor. We use an atomic force microscopy cantilever coated with a ferromagnetic thin film as a bimaterial sensor to measure absorption of microwaves at 9

Absolute Magnetic Moment Measurements of Nickel Spheres

May 1, 2000
Author(s)
Robert D. Shull, Robert D. McMichael, L Swartzendruber, Stefan D. Leigh
The preparation and measurement of nickel spheres for use in the calibration of magnetometers are described. The absolute value of the magnetic moment of a set these spheres near room temperature was measured using the Faraday method. The variations of

Behavior of MAG Standard Problem No. 2 in the Small Particle Limit

May 1, 2000
Author(s)
Michael J. Donahue, Donald G. Porter, Robert D. McMichael, J Eicke
For a uniformly magnetized rectangular particle with dimensions in the ratio 5 : 1 : 0.1, the coercive and switching fields in the (1,1,1) direction are determined to be H c / M s = 0.057069478 and H s / M s = 0.057142805. Previous micromagnetic

Domain Wall Traps for Low-Field Switching of Submicron Elements

May 1, 2000
Author(s)
Robert D. McMichael, J G. Eicke, Michael J. Donahue, Donald G. Porter
In magnetic random access memory, power consumption depends on the coercivity of the magnetic elements in the memory cells. In this article a new method is described that uses a domain wall trap element shape to reduce both the coercivity and the

Exchange Bias Relaxation in CoO-Biased Films

May 1, 2000
Author(s)
Robert McMichael, Chang H. Lee, Mark D. Stiles, F Serpa, P J. Chen, William F. Egelhoff Jr.
Because the memory of the bias direction is carried by the antiferromagnetic order in exchange bias films, the stability of the antiferromagnetic order is critical to the existence of the exchange bias field. Ferromagnetic resonance was used to measure the

Switching Mechanism of Single Domain Particles in a Two-Dimensional Array

September 1, 1999
Author(s)
Martha Pardavi-Horvath, G Vertesy, B Keszei, Z Vertesy, Robert D. McMichael
The mechanism of switching of uniaxial, single domain, single crystalline epitaxial garnet particles on a 2D square array was investigated. The anisotropy field of the sample is 2 kOe, while the gaussian switching field distribution is 280 85 Oe. The