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Search Publications by: Cindi L. Dennis (Fed)

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Displaying 26 - 42 of 42

Controlling the Self-Assembly of Metal-Seamed Organic Nanocapsules

January 3, 2012
Author(s)
Harshita Kumari, Andrew V. Mossine, Steven R. Kline, Cindi L. Dennis, Drew A. Fowler, Simon J. Teat, Charles L. Barnes, Carol A. Deakyne, Jerry L. Atwood
Puzzling out the intricacies associated with formation of supramolecular structures provides insight into and control of the self-assembly process. Such control may allow tailoring of these structures for specific applications. Herein we report the results

Magnetization Reversal Mechanisms in Heusler Alloy Spin Valves

March 29, 2011
Author(s)
T. P. Ginley, Julie Borchers, Brian Kirby, Cindi L. Dennis, Matthew J. Carey, J. R. Childress
Ferromagnetic layers composed of Heusler alloys, which are predicted to be 100% spin polarized in bulk, have been incorporated into spin-valve sensors to improve performance. Transport studies of spin valves containing Co 2MnGe (CMG) in the free and pinned

Controlling High Coercivities of Ferromagnetic Nanowires Encapsulated in Carbon Nanotubes

June 15, 2010
Author(s)
Robert D. Shull, Cindi L. Dennis, A. Morelos-Gomez, Florentino N. Lopez-Urias, Emilio N. Munoz-Sandoval, H. Terrones, M. Terrones
Cylindrical ferromagnetic nanowires encapsulated inside multiwalled carbon nanotubes (MWNTs) are synthesized by pyrolizing either ferrocene powder or ferrocene-toluene mixtures. By changing the way the precursor is thermolyzed, we have been able to control

Synthetic Mica: A Very Promising Substrate for Studying Solid Thin Films by Proton NMR

August 25, 2009
Author(s)
David L. VanderHart, Vivek M. Prabhu, Kristopher Lavery, Cindi L. Dennis
We demonstrate that a synthetic fluorophlogopite mica can be used as a proton-free, diamagnetic substrate for examining solid thin-film samples using conventional solid-state proton NMR experiments. The context of this work extends previous NMR studies on

Thin Film Solid State Proton NMR Measurements Using A Synthetic Mica Substrate: Polymer Blends

August 25, 2009
Author(s)
David L. VanderHart, Vivek Prabhu, Kristopher Lavery, Cindi L. Dennis, Ashwin Rao, Eric K. Lin
We demonstrate that a synthetic fluorophlogopite mica can be used as a proton-free, diamagnetic substrate for examining solid thin-film samples using conventional solid-state proton nuclear magnetic resonance (NMR) experiments. The context of this work

Probing the Growth and Aging of Colloidal Cobalt Nanoparticles

June 11, 2009
Author(s)
Guangjun Cheng, Cindi L. Dennis, Robert D. Shull, Angela R. Hight Walker
We have combined transmission electron microscopy (TEM) and magnetic measurements to characterize the growth of colloidal cobalt (Co) nanoparticles during synthesis and their subsequent stability in air. During the growth, TEM measurements have shown the

Detection of Pinholes in Magnetic Tunnel Junctions by Magnetic Coupling

October 16, 2008
Author(s)
Philip Pong, Cindi L. Dennis, Audie M. Castillo, Andrew P. Chen, William F. Egelhoff Jr.
Pinholes in tunnel barriers are detrimental to the performance of magnetic tunnel junctions (MTJ) since they create direct magnetic exchange coupling between the free and pinned magnetic films and may act as current short circuits. A simple and

Evidence for Electrical Spin Injection Into Silicon

October 16, 2008
Author(s)
Cindi L. Dennis, J F. Gregg, G J. Ensell, S M. Thompson
Electrical spin injection into silicon was studied in a ferromagnet/insulator/silicon/insulator/ferromagnet structure, where the insulator is Si3N4. Si3N4 barriers conduct by hopping conduction (HC) at low voltages, but switch to Fowler-Nordheim tunneling

Physical characterization methods for iron-oxide contrast agents encapsulated within a targeted liposome-based delivery system

April 16, 2008
Author(s)
John A. Dagata, Natalia Farkas, Cindi L. Dennis, Robert D. Shull, Vincent A. Hackley, Charles W. Yang, Kathleen F. Pirollo, Esther H. Chang
Intact liposome-based targeted nanoparticle delivery systems (NDS) are immobilized by nonselective binding and characterized by scanning probe microscopy (SPM) in a fluid imaging environment. The size, size distribution, functionality, and stability of an

Influence of the Colloidal Environment on the Magnetic Behavior of Cobalt Nanoparticles

November 6, 2007
Author(s)
Guangjun Cheng, Cindi L. Dennis, Robert D. Shull, Angela R. Hight Walker
The magnetic properties of 10 nm cobalt (Co) nanoparticles in 1,2-dicholorbenenze (DCB) are investigated via a series of magnetization (M) vs. temperature (T) measurements. A rapid rise in magnetization around 250 K during warming and a sudden drop at 240

Preoxidation as a general approach to suppressing orange-peel coupling in magnetic tunnel junctions

October 1, 2006
Author(s)
William F. Egelhoff Jr., Robert McMichael, Cindi L. Dennis, Mark D. Stiles, Alexander J. Shapiro, Brian B. Maranville, Cedric J. Powell
We have found that preoxidation of the bottom electrode prior to deposition of Al 2O 3 or MgO is very effective as a general approach to suppressing orange-peel coupling in magnetic tunnel junctions. When orange-peel coupling is suppressed, the hard-axis

Soft magnetic layers for low-field-detection magnetic sensors

May 18, 2006
Author(s)
William F. Egelhoff Jr., Robert McMichael, Cindi L. Dennis, Mark D. Stiles, Freemon Johnson, Alexander J. Shapiro, Brian B. Maranville, Cedric J. Powell
We have investigated a wide variety of soft magnetic layers as sense layers for magnetic-field sensors. We find that in thin-film form, some of these soft materials can have susceptibilities (?) approaching those of the corresponding bulk material. In

Suppression of Orange-Peel Coupling in Magnetic Tunnel Junctions by Preoxidation

April 17, 2006
Author(s)
William F. Egelhoff Jr., Robert McMichael, Cindi L. Dennis, Mark D. Stiles, Alexander J. Shapiro, Brian B. Maranville, Cedric J. Powell
We have found that preoxidation of the bottom Co electrode in magnetic tunnel junctions (MTJs) very effectively suppresses orange-peel coupling. The result is a free layer that is much softer. Work by others has demonstrated that preoxidation is compatible