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Search Publications by: Robert D. McMichael (Fed)

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Displaying 76 - 100 of 160

Artifacts in Ballistic Magnetoresistance Measurements

June 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, H Ettedgui, Y Kadmon, Cedric J. Powell, P J. Chen, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles, Erik B. Svedberg
We have studied the behavior of electrodeposited Ni and Fe nanocontacts in magnetic fields and the changes in resistivity (Δ}R) that occur. Metallic particles suspended in plating solution, created and collected from the electroplating bath of a

Artifacts in Ballistic Magnetoresistance Measurements

June 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, H Ettendgui, Y Kadmon, Cedric J. Powell, P J. Chen, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles
We have carried out an extensive search for credible evidence to support the existence of a ballistic magnetoresistance (BMR) effect in magnetic nanocontacts. We have investigated both thin-film and thin-wire geometries for both mechanically-formed and

Ferromagnetic Resonance Linewidth Models for Perpendicular Media

June 1, 2004
Author(s)
Robert D. McMichael
Ferromagnetic resonance linewidth in pendicular recording media is modeled with inhomogeneous uniaxial anisotropy field H u and with tilting of the easy axes from the film normal. The linewidth is calculated using both a local resonance model and a

Artifacts that mimic ballistic magnetoresistance

January 1, 2004
Author(s)
William F. Egelhoff Jr., L Gan, Erik B. Svedberg, Cedric J. Powell, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles
We have investigated the circumstances underlying recent reports of very large values of ballistic magnetoresistance (BMR) in nanocontacts between magnetic wires. We find that the geometries used are subject to artifacts due to motion of the wires that

Coercivities above 10 kOe in CoPd Superlattices

January 1, 2004
Author(s)
William F. Egelhoff Jr., Cedric J. Powell, L Gan, P J. Chen, H Ettendgui, D Tirosh, Robert McMichael, Mark D. Stiles, J Mallett, Alexander J. Shapiro, John E. Bonevich
We have achieved excellent grain isolation in CoPd superlattices by using 10 nm Au as both an underlayer and an overlayer and diffusing Au into the grain boundaries by annealing for approximately equal to} 30 min. at 300 degrees C. The grain isolation

Structure and Magnetic Properties of Electrodeposition Co on n-GaAs (001)

September 19, 2003
Author(s)
A X. Ford, John E. Bonevich, Robert D. McMichael, Mark D. Vaudin, Thomas P. Moffat
Co thin films have been electrodeposited on n-type (001) GaAs. The structure and texture of the films were investigated using x-ray diffraction (XRD) and transmission electron microscopy (TEM) while the magnetic properties were examined using a vibrating

Localized Ferromagnetic Resonance in Inhomogeneous Thin Films

June 1, 2003
Author(s)
Robert McMichael, A Kunz, D J. Twisselmann
The effect of sample inhomogeneity on the ferromagnetic resonance line width is determined by diagonalization of a spin wave Hamiltonian for ferromagnetic thin films with inhomogeneities. The resonance line broadening results from the distribution of the

Magnetic and Structural Characterization and Ferromagnetic Resonance Study of Thin Film HITPERM Soft Magnetic Materials for Data Storage Applications

May 1, 2003
Author(s)
Hideyuki Okumura, D J. Twisselmann, Robert McMichael, M Q. Huang, Y N. Hsu, D E. Laughlin, M E. McHenry
HITPERM/SiO 2 single and multilayer thin films have been produced using a target composition of (Fe 70 Co 30 ) 88 }Zr 7 }B 4 }Cu 1 }. The as-deposited HITPERM film contains small bcc (or B2) nanocrystals of volume fraction less than 10% surrounded by an

Magnetization Dynamics Modeled in Magnetic Thin Films

March 1, 2003
Author(s)
Robert D. McMichael
One of the challenges facing designers of high data rate computer hard drives and magnetic memory chips is that for most magnetic metals, it typically takes a fewnanoseconds for the magnetization to come to rest after it has been switched or bumped by a

Ru Spacer Thickness Dependences of the Domain Nucleation and Growth in Co/Ru/Co Synthetic Antiferromagnet

March 1, 2003
Author(s)
V S. Gornakov, Valerian I. Nikitenko, William F. Egelhoff Jr., Robert D. McMichael, Alexander J. Shapiro, Robert D. Shull
The relative orientation of Co magnetization vectors in a Co/Ru/Co/Ta structure vary gradually from parallel to antiparallel orientation as a function of Ru thickness varying from 0 nm to 1.0 nm. At intermediate average Ru thicknesses from 0.2 nm to 0.35

High-speed switching and rotational dynamics in small magnetic thin-film devices

January 1, 2003
Author(s)
Stephen E. Russek, Shehzaad F. Kaka, Robert McMichael, Michael J. Donahue
The intent of this chapter is to review high frequency magnetic device measurements and modeling work at NIST which is being conducted to support the development of high-speed read sensors, magnetic random access memory, and magnetoelectronic applications

Magnetic Properties of Ultrathin Laminated Co/Cu Films Prepared by Electrodeposition

September 1, 2002
Author(s)
M Shima, L Salamanca-Riba, Thomas P. Moffat, Robert D. McMichael
The magnetic properties of a series of electrodeposited [Co(x ML)/Cu(17 ML)]100 multilayers have been examined as a function of the cobalt layer thickness. The multilayers were grown on Si(100)covered with a highly textured Cu(100) seed alyer. Films with a

Normal Mode Mixing and Ferromagnetic Resonance Linewidth

September 1, 2002
Author(s)
A B. Kunz, Robert D. McMichael
This spin wave modes for a uniform film are perturbed by the inclusion of inhomogeneities into the system. The resulting perturbed Hamiltonianis diagonalized to create a new set of spin waves modes. The effect of the strength of the perturbations is

Anomalous Switching Behavior of Antiparallel-Coupled CO Layers Separated by a Super-Thin Ru Spacer

May 15, 2002
Author(s)
V S. Gornakov, Valerian I. Nikitenko, William F. Egelhoff Jr., Robert D. McMichael, Alexander J. Shapiro, Robert D. Shull
The details of the magnetization reversal mechanisms upon field reversal in coupled ferromagnetic CO (2.5 nm)/Ru(0.5 nm)/Co (2.6 nm) trilayers deposited on obliquely sputtered Ta (10.6 nm) underlayers were studied using the magneto-optical indicator film

Magnetostriction and angular dependence of FMR linewidth in Tb-doped Ni 0.8 Fe 0.2 thin films

May 15, 2002
Author(s)
Stephen E. Russek, Pavel Kabos, Robert McMichael, C G. Lee, William E. Bailey, R Ewasko, S. Sanders
We present the dependence of the magnetostriction in Ni 0.8 Fe 0.2 films on Tb and Gd doping concentration with the measured doping dependence of the high-frequency damping. While the magnetostriction and the high-frequency damping are correlated, the

Ferromagnetic Resonance Mode Interactions in Periodically Perturbed Films

May 1, 2002
Author(s)
Robert McMichael, D J. Twisselmann, John E. Bonevich, P J. Chen, William F. Egelhoff Jr., Stephen E. Russek
rromagnetic resonance linewidth measurements are reported for thin films of Ni 80 Fe 20 deposited on substrates with 320 nm period grooves or parallel aperiodic scratches. These films are model systems for studying the effects of inhomogeneity on

Structural Magnetic and Thermal Stability of IrMn Exchange Biased Layers

May 1, 2002
Author(s)
Chang H. Lee, J G. Jung, Robert D. McMichael, R A. Fry, Andrew P. Chen, William F. Egelhoff Jr., V S. Gornakov
The magnetic domain structure, magnetic properties and thermal stability of IrMn biased top spin valves containing Co and NiFe have been investigated. The magneto-optical indicator film (MOIF) pictures of NiFe biased IrMn spin valve showed the formation

Features of Domain Nucleation and Growth in Co/Ru/Co Synthetic Antiferromagnets Deposited on Obliquely Sputtered Ta Underlayers

February 1, 2002
Author(s)
Alexander J. Shapiro, V S. Gornakov, Valerian I. Nikitenko, Robert D. McMichael, William F. Egelhoff Jr., Y W. Tahk, Robert D. Shull, L Gan
Obliquely sputtered Ta underlayers were used to stabilize antiferromagnetically couple Co/Ru/Co/Ta structures with a strong uniaxial anistropy. Magneto-optical indicator film (MOIF) imaging revealed nucleation and growth of domains during remagnetization

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

August 1, 2001
Author(s)
M. Menyhard, G. Zsolt, P. J. Chen, Cedric J. Powell, Robert D. McMichael, William F. Egelhoff Jr.
An investigation has been made of the thin-film structure and interface morphology of giant magnetoresistance (GMR) spin valves of the cobalt/copper/cobalt (Co/Cu/Co) type that were grown on polycrystalline NiO substrates at three different temperatures