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- Barium hexaferrite (2)
- Aluminum isopropoxide (1)
- Al₂O₃ (1)
- Anisotropic ferrite magnetic materials (1)
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- BaFe₁₂₋ₓScₓO₁₉ platelets (1)
- Chemical coprecipitation (1)
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- Co acetate tetrahydrate (1)
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- Electronically controlled multiferroic devices (1)
- Epitaxial film (1)
- FMR (1)
- Fe(II) chloride (1)
- FeCo alloy (1)
- Ferrite-dielectric-wire composite negative index materials (1)
- Ferromagnetic air stable SmCo nanoparticles (1)
- Finite difference time domain simulations (1)
- Focusing concave lens (1)
- GaAs (1)
- Growth-rate-induced cation inversion (1)
- High frequency applications (1)
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Articles 1 - 10 of 10
Full-Text Articles in Engineering
Microwave Magnetoelectric Coupling And Ferromagnetic Resonance Frequency Tuning Of A Co₂Mnsb/Gaas/Pzn-Pt Heterostructure, Yajie Chen, Aria Yang, Moti Paudel, Shane Stadler, C. Vittoria, V. Harris
Microwave Magnetoelectric Coupling And Ferromagnetic Resonance Frequency Tuning Of A Co₂Mnsb/Gaas/Pzn-Pt Heterostructure, Yajie Chen, Aria Yang, Moti Paudel, Shane Stadler, C. Vittoria, V. Harris
Vincent G. Harris
A systematic study of electric-field-tuned ferromagnetic resonance (FMR) of a ferroelectric/ferromagnetic/semiconductor multiferroic heterostructure, consisting of a Co₂MnSb epitaxial film grown on a GaAs substrate bonded to a lead zinc niobate-lead titanate crystal, is reported. The films, grown by pulsed laser deposition, were studied for their crystallographic structure, magnetocrystalline anisotropy, and magnetostrictive and ferromagnetic resonance properties. Ferromagnetic resonance measurements were carried out at X-band frequency under the application of electric fields with external magnetic fields applied along the [110], [100], [1Ī0] and [001] directions of the Heusler film. Magnetic anisotropy fields were derived from the angular dependence of FMR measurements, yielding …
Screen Printed Thick Self-Biased, Low-Loss, Barium Hexaferrite Films By Hot-Press Sintering, Yajie Chen, Tomokazu Sakai, Taiyang Chen, Soack Yoon, Carmine Vittoria, Vincent Harris
Screen Printed Thick Self-Biased, Low-Loss, Barium Hexaferrite Films By Hot-Press Sintering, Yajie Chen, Tomokazu Sakai, Taiyang Chen, Soack Yoon, Carmine Vittoria, Vincent Harris
Vincent G. Harris
BaFe₁₂O₁₉ hexaferrite thick films having high hysteresis loop squareness (Mr/Ms) and low ferromagnetic resonance (FMR) linewidths were processed through the use of a screen printing technique coupled with hot-press sintering. Scanning electron microscopy and x-ray diffraction measurements exhibit strong crystallographic c-axis alignment of crystals perpendicular to the film plane. Static magnetic resonance and FMR measurements were performed to determine the effect of the preparation technique on magnetic hysteresis and microwave properties. Hot pressing during sintering produced dense thick films having high squareness (> 0.95) and reduced coercivity (∽1900 Oe). Of greater importance was the measurement of a minimum peak-to-peak FMR …
Large Tunability Of Néel Temperature By Growth-Rate-Induced Cation Inversion In Mn-Ferrite Nanoparticles, Aria Yang, C. Chinnasamy, J. Greneche, Yajie Chen, Soack Yoon, Kailin Hsu, C. Vittoria, V. Harris
Large Tunability Of Néel Temperature By Growth-Rate-Induced Cation Inversion In Mn-Ferrite Nanoparticles, Aria Yang, C. Chinnasamy, J. Greneche, Yajie Chen, Soack Yoon, Kailin Hsu, C. Vittoria, V. Harris
Vincent G. Harris
The tuning of Néel temperature by greater than 100 K in nanoparticle Mn-ferrite was demonstrated by a growth-rate-induced cation inversion. Mn-ferrite nanoparticles, having diameters from 4 to 50 nm, were synthesized via coprecipitation synthesis. The Neel temperature (TN) increased inversely to the cation inversion parameter,δ (i.e., defined as (Mn1-δFeδ)tet[MnδFe2-δ]octO₄). Concomitantly, TN increased with increased particle growth rate and particle size. These results unambiguously establish cation inversion as the dominant mechanism in modifying the superexchange leading to enhanced TN. The ability to tailor TN enables greater flexibility in applying nanoparticle ferrites in emerging technologies.
Simulations Of Ferrite-Dielectric-Wire Composite Negative Index Materials, Frederic Rachford, Douglas Armstead, Vincent Harris, Carmine Vittoria
Simulations Of Ferrite-Dielectric-Wire Composite Negative Index Materials, Frederic Rachford, Douglas Armstead, Vincent Harris, Carmine Vittoria
Vincent G. Harris
We perform extensive finite difference time domain simulations of ferrite based negative index of refraction composites. A wire grid is employed to provide negative permittivity. The ferrite and wire grid interact to provide both negative and positive index of refraction transmission peaks in the vicinity of the ferrite resonance. Notwithstanding the extreme anisotropy in the index of refraction of the composite, negative refraction is seen at the composite air interface allowing the construction of a focusing concave lens with a magnetically tunable focal length.
Large-Scale Chemical Synthesis Of Shape And Size Controlled Bafe₁₂₋ₓscₓo₁₉ Platelets For In-Plane Oriented Thick Screen Printed Films, T. Sakai, C. Chinnasamy, S. Yoon, A. Geiler, C. Vittoria, V. Harris
Large-Scale Chemical Synthesis Of Shape And Size Controlled Bafe₁₂₋ₓscₓo₁₉ Platelets For In-Plane Oriented Thick Screen Printed Films, T. Sakai, C. Chinnasamy, S. Yoon, A. Geiler, C. Vittoria, V. Harris
Vincent G. Harris
Scandium (Sc) doped, single phase BaFe₁₂₋ₓScₓO₁₉ (x=0.3 and 0.8) were prepared at large scale (10 g) by a modified chemical coprecipitation technique. The scanning electron micrograph analysis shows the formation of nearly uniform hexagonal platelets with an average size of < 1 μm. The sizes of the platelets were controlled by sintering temperature. The screen printed, in-plane oriented films were annealed at different temperatures to produce a dense and thick ferrite film. The hysteresis loops for x=0.3 show a squareness ratio of 0.9 and the saturation magnetic moment of 3700 G and the coercivity of 250 Oe. The saturation magnetic moment …
Numerical Simulation Of Wave Propagation In Y- And Z-Type Hexaferrites For High Frequency Applications, J. Wang, A. Geiler, V. Harris, C. Vittoria
Numerical Simulation Of Wave Propagation In Y- And Z-Type Hexaferrites For High Frequency Applications, J. Wang, A. Geiler, V. Harris, C. Vittoria
Vincent G. Harris
The dispersion characteristics of microstrip lines on magnetically anisotropic substrates are studied utilizing the Galerkin's method in the spectral domain. Specifically, we calculate the differential phase shifts of devices consisting of Z-type (Zn₂Z) and Y-type (Zn₂Y) ferrites as a function of applied magnetic field. Our theoretical formulism is effective in modeling highly magnetically anisotropic materials, which are becoming increasingly important for the next generation of microwave devices. Such a theoretical treatment of anisotropic ferrite magnetic materials is presently unavailable in commercial numerical simulation tools.
Low-Loss Barium Ferrite Quasi-Single-Crystals For Microwave Application, Yajie Chen, Anton Geiler, Taiyang Chen, Tomokazu Sakai, C. Vittoria, V. Harris
Low-Loss Barium Ferrite Quasi-Single-Crystals For Microwave Application, Yajie Chen, Anton Geiler, Taiyang Chen, Tomokazu Sakai, C. Vittoria, V. Harris
Vincent G. Harris
Barium hexaferrites (BaFe₁₂O₁₉) are especially useful for microwave/millimeter devices. Due to large ferromagnetic resonance (FMR) loss (linewidths > 2 kOe), traditional compacts of polycrystalline Ba ferrites indeed hinder the utilization of the materials for practical devices. The present experiment demonstrates that the quasi-single-crystal Ba ferrite disks can be fabricated by a single solid-state reaction technique without liquid phase participation, combining with a processing of alignment for the ferrite seed crystals. The ferrite bulks show a pure hexagonal Ba ferrite phase, an expected 4πMs of 4.48 kG, and coercivity of 10∽20 Oe along the c axis, similar to the results of a …
A Microstrip Tunable Negative Refractive Index Metamaterial And Phase Shifter, P. He, J. Gao, C. Marinis, P. Parimi, C. Vittoria, V. Harris
A Microstrip Tunable Negative Refractive Index Metamaterial And Phase Shifter, P. He, J. Gao, C. Marinis, P. Parimi, C. Vittoria, V. Harris
Vincent G. Harris
A tunable negative refractive index metamaterial and miniature phase shifter have been designed and fabricated in a microstrip configuration for applications in radio frequency integrated circuits. The metamaterial consists of plasmonic copper wires and yttrium iron garnet slabs having a low insertion loss of 5 dB at the center of the transmission band. The yttrium iron garnet material enables the magnetic field tuning of the negative refractive index in a dynamic frequency band from 7.0 to 11.0 GHz. The insertion phase can be tuned by 45 degrees continuously by varying the bias field from 3.8 to 4.6 kOe at 9.0 …
Functionalization Of Feco Alloy Nanoparticles With Highly Dielectric Amorphous Oxide Coatings, Q. Nguyen, C. Chinnasamy, S. Yoon, S. Sivasubramanian, T. Sakai, A. Baraskar, S. Mukerjee, C. Vittoria, V. Harris
Functionalization Of Feco Alloy Nanoparticles With Highly Dielectric Amorphous Oxide Coatings, Q. Nguyen, C. Chinnasamy, S. Yoon, S. Sivasubramanian, T. Sakai, A. Baraskar, S. Mukerjee, C. Vittoria, V. Harris
Vincent G. Harris
FeCo alloy nanoparticles have been prepared by using a two step modified polyol process using Fe(II) chloride and Co acetate tetrahydrate as Fe and Co metal precursors. Tetraethyl silicate, aluminum isopropoxide, and zirconium(IV) acetyl acetonate were used to make amorphous SiO₂, Al₂O₃, and ZrO₂ coatings, respectively. X-ray diffraction studies showed that there are no crystalline peaks corresponding SiO₂, Al₂O₃, and ZrO₂ because the oxide coatings of the FeCo core are amorphous in nature. The scanning electron micrograph analysis depicted the cubic nature of the particles with mean particle size of about 45 nm. The maximum saturation magnetization of 205 emu/g …
Direct Chemical Synthesis Of High Coercivity Air-Stable Smco Nanoblades, C. Chinnasamy, J. Huang, L. Lewis, B. Latha, C. Vittoria, V. Harris
Direct Chemical Synthesis Of High Coercivity Air-Stable Smco Nanoblades, C. Chinnasamy, J. Huang, L. Lewis, B. Latha, C. Vittoria, V. Harris
Vincent G. Harris
Ferromagnetic air-stable SmCo nanoparticles have been produced directly using a one-step chemical synthesis method. X-ray diffraction studies confirmed the formation of hexagonal SmCo5 as a dominant phase. High resolution transmission electron microscopy confirms the presence of uniform, anisotropic bladelike nanoparticles approximately 10 nm in width and 100 nm in length. Values of the intrinsic coercivity and the magnetization in the as-synthesized particles are 6.1 kOe and 40 emu/g at room temperature and 8.5 kOe and 44 emu/g at 10 K, respectively. This direct synthesis process is environmentally friendly and is readily scalable to large volume synthesis to meet the needs …