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Search Publications by Cindi L. Dennis

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Displaying 1 - 25 of 39

Design and Engineering Colloidal Magnetic Particles for Nanoscale Thermometry

September 2, 2020
Adam J. Biacchi, Thinh Q. Bui, Cindi L. Dennis, Solomon I. Woods, Angela R. Hight Walker
Thermometry based on magnetic nanoparticles (MNPs) is an emerging technology that allows for remote temperature measurements throughout a volume that are impossible to achieve using conventional probe-based or optical methods. This metrology is based on

Quasi-two-dimensional magnon identification in antiferromagnetic FePS3 via magneto-Raman spectroscopy

February 18, 2020
Amber D. McCreary, Jeffrey R. Simpson, Thuc T. Mai, Robert D. McMichael, Jason E. Douglas, Nicholas P. Butch, Cindi L. Dennis, Rolando Valdes Aguilar, Angela R. Hight Walker
Recently it was discovered that van der Waals-bonded magnets retain long range magnetic ordering even down to a monolayer thickness, opening many avenues in fundamental physics and potential applications of these fascinating materials. One example is FePS3

Nanoparticle Architecture Preserves Magnetic Properties during Coating to Enable Robust Multi-Modal Functionality

August 23, 2018
Lauren E. Woodard, Cindi L. Dennis, Julie A. Borchers, Anilchandra Attaluri, Esteban Velarde, Charlene Dawidczyk, Peter C. Searson, Martin G. Pomper, Robert Ivkov
Mixed metal/metal oxide nanoparticles offer potential as multifunctional platforms for disease diagnosis and therapy, or 'theranostics' [1-9]. We describe the synthesis and characterization of gold/silica/iron oxide core-shell nanoparticles, for which the

Fe 2 MnGe: A Hexagonal Heusler Analogue

August 20, 2018
S. Keshavarz, N. Naghibolashrafi, Michelle Elizabeth Jamer, K. Vinson, D. Mazumdar, Cindi L. Dennis, William D. Ratcliff, Julie A. Borchers, A. Gupta, P. LeClair
Fe2MnGe is a potential half-metallic full-Heusler L21 ferromagnetic compound with large spin polarization ({approximately equal}97%) useful for various spintronic applications according to our first principles calculations using density functional theory

Electric-field control of perpendicular magnetic anisotropy in multiferroic PZT- and PMN- PT//[Co/Ni] composites with negative magnetostriction

July 4, 2018
Daniel B. Gopman, Andrew P. Chen, Cindi L. Dennis, June W. Lau, Robert D. Shull, Gregory P. Carman, Peter Finkel, Margo Staruch, Andres Chavez
A longstanding goal of spintronics is to identify alternatives to current-generated Oersted- fields for magnetization control at the nanoscale. An emerging approach seeks to harness the voltage-induced strain in a proximal piezostrictive layer to modify

Enhanced ferromagnetic resonance linewidth of the free layer in perpendicular magnetic tunnel junctions

March 3, 2017
Daniel B. Gopman, Cindi L. Dennis, Robert D. McMichael, Xiaojie Hao, Zihui Wang, Xiaobin Wang, Huadong Gan, Yuchen Zhou, Jian Zhang, Yiming Huai
We report the frequency dependence of the ferromagnetic resonance linewidth of the free layer in magnetic tunnel junctions with all perpendicular-to-the-plane magnetized layers. While the magnetic-fi eld-swept linewidth nominally shows a linear growth with

Magnetic Properties and Applications of Engineered Nanomaterials

January 20, 2017
Cindi L. Dennis
This chapter will review the fundamentals of nanomagnetism, including its origins, the different types, and their response at the nanoscale, followed by applications of nanomagnetics. Unfortunately, due to space constraints, this chapter cannot be

Artifacts in magnetic measurements of fluid samples

August 24, 2016
Cindi L. Dennis, Zoe A. Boekelheide
Applications of magnetic fluids are ever increasing, as well as the corresponding need to be able to characterize these fluids in situ. Commercial magnetometers are accurate and well-characterized for solid and powder samples, but their use with fluid

Effect of Grain Constraint on the Field Requirements for Magnetocaloric Effect in Ni(sub45)Co(Sub5)Mn(Sub40)Sn(sub10) Melt-Spun Ribbons

August 21, 2016
N. M. Bruno, Y. J. Huang, Cindi L. Dennis, J. G. Li, Robert D. Shull, J. H. Ross Jr., Y. I. Chumlyakov, I. Karaman
The influence of grain constraint on the magnetic field levels required to complete the isothermal martensitic transformation in magnetic shape memory alloys has been demonstrated for a NiCoMnSn alloy and the magnetocaloric performance of an optimally heat

Measurement and Modeling of Polarized Specular Neutron Reflectivity in Large Magnetic Fields

August 1, 2016
Brian B. Maranville, Brian J Kirby, Alexander J Grutter, Paul Kienzle, Charles F. Majkrzak, Yaohua Liu, Cindi L. Dennis
The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrodinger equation

Magnetocaloric Response Of Non-Stoichiometric Ni(sub2)MnGa Alloys and the Influence of Texture

November 1, 2015
Michael V. McLeod, Anit Giri, Brigitte A. Paterson, Cindi L. Dennis, H L. Zhou, S C. Vogel, Yong Ho Sohn, Robert D. Shull, B S. Majumdar
Currently, there is significant interest in magnetocaloric materials for solid state refrigeration. In this work, polycrystalline Heusler alloys belonging to the Ni(sub2+x)Mn(sub 1-x) Ga family, with x between 0.08 and 0.24, were evaluated for the purpose

Internal Magnetic Structure of Nanoparticles Dominates Time-Dependent Relaxation Processes in a Magnetic Field

June 2, 2015
Cindi L. Dennis, Kathryn L. Krycka, Julie A. Borchers, Ryan D. Desautels, Johan van Lierop, Natalie F. Huls, Andrew J. Jackson, Cordula Gruettner, Robert Ivkov
Time-dependent relaxation of nanomagnets, such as magnetic nanoparticles, have applications in many disciplines of science and technology because these magnets can exhibit hysteresis and loss power when exposed to AC magnetic fields. In particular, the

Details of the Magnetization Reversal in Patterned Exchange-biased and Unbiased Thin Films

November 1, 2014
Robert D. Shull, Y. P. Kabanov, Andrew P. Chen, Cindi L. Dennis, V S. Gornakov, Valerian I. Nikitenko
New features of the magnetization reversal of a patterned bilayer in the form of a square mesh consisting of 16 um wide intersecting stripes of Ni(sub79)Fe(sub21) (30 nm) exchange-coupled with IrMn (10 um) on top were revealed via use of the advanced

Chloride-Bridged, Defect-Dicubane {Ln 4 } Core Clusters: Syntheses, Crystal Structures and Magnetic Properties

August 21, 2014
Daniel M Pajerowski, Quan Li, Jason Hyun, Cindi L. Dennis, Daniel Phelan, Pengfei Yan, Peng Chen, Guangming Li
Three chlorid-bridged lanthanide compounds, [Ln4Cl6(CH3OH)12(OH)2𔅘CL𔅖CH3OH [Ln=Gd (1), Dy (2) and Er (3)], have been unexpectedly isolated by the reactions of LnCl3𔅚H2O and N,N'-bis(salicylidene)-1,2-(phenylene-diamine) (H2L). X-ray crystallographic

Solution-phase and Magnetic Approach Towards Understanding Iron Gall Inks

August 13, 2012
Harshita Kumari, Steven R. Kline, Cindi L. Dennis, Andrew V. Mossine, Rick L. Paul, Carol A. Deakyne, Jerry L. Atwood
Crystallization of compounds of iron with polyphenols, such as iron gall inks, has been an ongoing challenge. As with iron-gall inks, iron complexes of 1,2,3-trihydroxphenol-containing marocycles have also proved difficult to crystallize. Despite this

Controlling the Self-Assembly of Metal-Seamed Organic Nanocapsules

January 3, 2012
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
T. P. Ginley, Julie A. Borchers, Brian J. 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 Co2MnGe (CMG) in the free and pinned

Controlling High Coercivities of Ferromagnetic Nanowires Encapsulated in Carbon Nanotubes

June 15, 2010
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