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- Microwave properties (9)
- Saturation magnetization (7)
- FMR (5)
- Magnetoelectric coupling (5)
- BaFe₁₂O₁₉ (4)
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- Barium hexaferrite (4)
- X-ray diffraction (4)
- ATLAD (3)
- Screen printed films (3)
- Al₂O₃ (2)
- BaFe₂O₄ (2)
- Cation inversion (2)
- FeCoV (2)
- Fe₂O₃ (2)
- Heterostructures (2)
- High frequency applications (2)
- Hysteresis loop (2)
- Lead magnesium niobate lead titanate (2)
- Magnetic anisotropy (2)
- Magnetic fields (2)
- MgO substrates (2)
- Nanocrystalline films (2)
- PMN-PT (2)
- Quartz substrates (2)
- Saturation magnetic moment (2)
- TN (2)
- Thin films (2)
- Α-Fe₂O₃ (2)
- (Ni₀.₆₇Co₀.₂₅Fe₀.₀₈)₈₉₋ₓZr₇B₄Cuₓ (x=0 (1)
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Articles 1 - 30 of 53
Full-Text Articles in Engineering
Domain Rotation Induced Strain Effect On The Magnetic And Magneto-Electric Response In Cofe2o₄/Pb(Mg,Nb)O₃-Pbtio₃ Heterostructures, Zhiguang Wang, Ravindranath Viswan, Bolin Hu, Jie-Fang Li, V. G. Harris, D. Viehland
Domain Rotation Induced Strain Effect On The Magnetic And Magneto-Electric Response In Cofe2o₄/Pb(Mg,Nb)O₃-Pbtio₃ Heterostructures, Zhiguang Wang, Ravindranath Viswan, Bolin Hu, Jie-Fang Li, V. G. Harris, D. Viehland
Vincent G. Harris
The present work shows good control of both magnetic and electric properties with electric and magnetic fields, respectively, for epitaxial CoFe2O4 (CFO) films on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT). X-ray reciprocal space mapping revealed a transformation between a- and c-domains in the PMN-PT under electric field (E). Magnetic hysteresis loop and magnetic force microscopy (MFM) measurements showed a considerable change in the magnetic properties in specific areas of CFO layers poled by MFM probe tips. Furthermore, a pulsed electric field applied to the substrate was found to switch the magnetization of CFO between high and low values, depending on the polarity of E.
Tunable Fringe Magnetic Fields Induced By Converse Magnetoelectric Coupling In A Fega/Pmn-Pt Multiferroic Heterostructure, Trifon Fitchorov, Yajie Chen, Bolin Hu, Scott Gillette, Anton Geiler, Carmine Vittoria, Vincent Harris
Tunable Fringe Magnetic Fields Induced By Converse Magnetoelectric Coupling In A Fega/Pmn-Pt Multiferroic Heterostructure, Trifon Fitchorov, Yajie Chen, Bolin Hu, Scott Gillette, Anton Geiler, Carmine Vittoria, Vincent Harris
Vincent G. Harris
The fringe magnetic field, induced by magnetoelectric coupling in a bilayer Fe-Ga/Pb(Mg1/3Nb2/3)O3_PbTiO3 (PMN-PT) multifunctional composite, was investigated. The induced external field is characterized as having a butterfly hysteresis loop when tuned by an applied electric field. A tuning coefficient of the electrically induced fringe magnetic field is derived from the piezoelectric and magnetostrictive properties of the composite. A measured maximum tuning coefficient, 4.5 Oe/(kV cm−1), is found to agree well with theoretical prediction. This work establishes a foundation in the design of transducers based on the magnetoelectric effect.
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 …
Magnetic-Properties And Local Ordering During Thermal Annealing Of Amorphous Fe₇₅Ni5b₁₅Si₅ Films, S. A. Oliver, V. G. Harris, C. Vittoria, W. T. Elam, K. H. Kim, H. H. Hamdeh, M. Alhabash
Magnetic-Properties And Local Ordering During Thermal Annealing Of Amorphous Fe₇₅Ni5b₁₅Si₅ Films, S. A. Oliver, V. G. Harris, C. Vittoria, W. T. Elam, K. H. Kim, H. H. Hamdeh, M. Alhabash
Vincent G. Harris
The evolution of magnetic properties and local atomic ordering during thermal annealing has been studied for amorphous Fe₇₅Ni5B₁₅Si₅ thin films. Resistivity, vibrating sample magnetometer (VSM), ferromagnetic resonance (FMR), extended x-ray absorption fine structure (EXAFS), and Mossbauer effect (ME) measurements were taken on samples annealed at various temperatures ranging to film crystallization. The as-deposited samples are in a close-packed structure with little short-range order. Samples annealed above 200°C show ordering of the boron shell, but no indication of long-range ordering. With the exception of the anisotropy and coercive fields, no change in the magnetic or microwave magnetic parameters is observed for …
Oriented Barium Hexaferrite Thick Films With Narrow Ferromagnetic Resonance Linewidth, Y. J. Chen, T. Sakai, T. Y. Chen, S. D. Yoon, A. L. Geiler, C. Vittoria, V. G. Harris
Oriented Barium Hexaferrite Thick Films With Narrow Ferromagnetic Resonance Linewidth, Y. J. Chen, T. Sakai, T. Y. Chen, S. D. Yoon, A. L. Geiler, C. Vittoria, V. G. Harris
Vincent G. Harris
Hexagonal BaFe₁₂O₁₉ ferrite films, having thicknesses ranging from 200-500μm, were prepared by a screen printing process followed by sintering heat treatments. Structural, magnetic, and microwave measurements confirmed that the polycrystalline films were suitable for applications in self-biasing microwave devices in that they exhibited a large remanence (4πMr=3800 G), high hysteresis loop squareness (Mr/Ms=0.96) and low microwave loss. A derivative linewidth ΔH of 310 Oe was measured at 55.6 GHz. This represents the lowest ΔH measured in polycrystalline hexaferrite materials. ΔH can be further improved by reducing porosity and improving the c-axis orientation of grains in polycrystalline ferrite.
Structural And Size Dependent Magnetic Properties Of Single Phase Nanostructured Gadolinium-Iron-Garnet Under High Magnetic Field Of 32 Tesla, C. N. Chinnasamy, J. M. Greneche, M. Guillot, B. Latha, T. Sakai, C. Vittoria, V. G. Harris
Structural And Size Dependent Magnetic Properties Of Single Phase Nanostructured Gadolinium-Iron-Garnet Under High Magnetic Field Of 32 Tesla, C. N. Chinnasamy, J. M. Greneche, M. Guillot, B. Latha, T. Sakai, C. Vittoria, V. G. Harris
Vincent G. Harris
Here we report the single phase nanostructured Gd₃Fe₅O₁₂ garnets with different grain sizes (bulk, 75, 47, 35, and 22 nm) were prepared by ball milling for various milling times. Both the average grain size and the lattice parameter were estimated from the x-ray diffraction line broadening. The 57Fe Mӧssbauer spectra were recorded at 300 and 77 K for the samples with different grain sizes clearly evidenced the formation of Fe²⁺ ions induced by milling and the content of Fe²⁺ increases with milling time. At 4.2 K, a significant increase in saturation magnetization (+11%) has been observed for the 47 nm …
Electronic Tuning Of Magnetic Permeability In Co₂Z Hexaferrite Toward High Frequency Electromagnetic Device Miniaturization, Yajie Chen, Andrew Daigle, Trifon Fitchorov, Bolin Hu, Michael Geiler, Anton Geiler, C. Vittoria, V. G. Harris
Electronic Tuning Of Magnetic Permeability In Co₂Z Hexaferrite Toward High Frequency Electromagnetic Device Miniaturization, Yajie Chen, Andrew Daigle, Trifon Fitchorov, Bolin Hu, Michael Geiler, Anton Geiler, C. Vittoria, V. G. Harris
Vincent G. Harris
The magnetic and magnetostriction properties of Z-type cobalt-doped barium hexaferrite with perpendicular c-axis crystallographic texture are presented. The hexaferrite was utilized as a component in Co₂Z/lead magnesium niobate-lead titanate multiferroic heterostructures whose tunability of permeability with electric field in terms of ferromagnetic resonance shift was supported by experiments and theoretical calculation. A permeability change of 16% was measured by an induced magnetic field of 38 Oe under the application of 6 kV/cm of electric field. These findings lay the foundation for the application of Z-type hexaferrites in tunable rf and microwave devices valued for sending, receiving, and manipulating electromagnetic signals.
Microwave Tunability In A Gaas-Based Multiferroic Heterostructure: Co₂Mnal/Gaas/Pmn-Pt, Y. Chen, J. Gao, M. Liu, S. D. Yoon, A. L. Geiler, M. Nedoroscik, D. Heiman, N. X. Sun, C. Vittoria, V. G. Harris
Microwave Tunability In A Gaas-Based Multiferroic Heterostructure: Co₂Mnal/Gaas/Pmn-Pt, Y. Chen, J. Gao, M. Liu, S. D. Yoon, A. L. Geiler, M. Nedoroscik, D. Heiman, N. X. Sun, C. Vittoria, V. G. Harris
Vincent G. Harris
A strong magnetoelectric (ME) interaction is presented in a magnetostrictive-semiconductor-piezoelectric heterostructure that consists of the Huesler alloy, Co₂MnAl, GaAs, and lead magnesium niobate-lead titanate (PMN-PT). The laminated Co₂MnAl/GaAs/PMN-PT structure, having a thickness of 19 nm/180 μm/500 μm, demonstrates a ferromagnetic resonance (FMR) field shift of 28 Oe with an external electric field of 200 V across the PMN-PT substrate. This corresponds to a resonance frequency shift of similar to 125 MHz at X-band. It yields a large ME coupling (7 Oe cm/kV) and microwave tunability (similar to 32 MHz/kV cm⁻¹), compared to other trilayer multiferroic composite structures. In addition, static …
Magnetic And Microwave Properties Of Basal-Plane Oriented Bafe₁₁In1o₁₉ Ferrite Thick Films Processed By Screen Printing, C. N. Chinnasamy, T. Sakai, S. Sivasubramanian, Aria F. Yang, C. Vittoria, V. G. Harris
Magnetic And Microwave Properties Of Basal-Plane Oriented Bafe₁₁In1o₁₉ Ferrite Thick Films Processed By Screen Printing, C. N. Chinnasamy, T. Sakai, S. Sivasubramanian, Aria F. Yang, C. Vittoria, V. G. Harris
Vincent G. Harris
In-doped BaFe₁₁In1O₁₉ particles were prepared by a modified ceramic reaction using In2O₃, BaCo3, and Fe₂O₃ followed by mechanical dispersion. X-ray diffraction analysis confirmed the formation of pure BaFe₁₁In1O₁₉ phase and scanning electron micrographs showed platelet particles of about 1 μm in diameter. This powder was subsequently screen printed on alumina substrate using a suitable binder and oriented under a dc magnetic field of 15 kOe. The screen printed films were annealed at different durations to produce dense and thick ferrite materials. The hysteresis loops for the as-prepared and annealed screen printed, in-plane oriented films show a hysteresis squareness ratio (Mr/Ms) …
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.
Structure, Magnetic, And Microwave Properties Of Thick Ba-Hexaferrite Films Epitaxially Grown On Gan/Al₂O₃ Substrates, Z. Chen, A. Yang, K. Mahalingam, K. L. Averett, J. Gao, G. J. Brown, C. Vittoria, V. G. Harris
Structure, Magnetic, And Microwave Properties Of Thick Ba-Hexaferrite Films Epitaxially Grown On Gan/Al₂O₃ Substrates, Z. Chen, A. Yang, K. Mahalingam, K. L. Averett, J. Gao, G. J. Brown, C. Vittoria, V. G. Harris
Vincent G. Harris
Thick barium hexaferrite [BaO∙(Fe₂O₃)₆] films, having the magnetoplumbite structure (i.e., Ba M), were epitaxially grown on c-axis oriented GaN/Al₂O₃ substrates by pulsed laser deposition followed by liquid phase epitaxy. X-ray diffraction showed (0,0,2n) crystallographic alignment with pole figure analyses confirming epitaxial growth. High resolution transmission electron microscopy images revealed magnetoplumbite unit cells stacked with limited interfacial mixing. Saturation magnetization, 4πMs, was measured for as-grown films to be 4.1 ± 0.3 kG with a perpendicular magnetic anisotropy field of 16 ± 0.3 kOe. Ferromagnetic resonance linewidth, the peak-to-peak power absorption derivative at 53 GHz, was 86 Oe. These properties will prove …
Room Temperature Magnetism In Semiconducting Films Of Zno Doped With Ferric Ions, S. D. Yoon, Y. J. Chen, D. Heiman, A. Yang, N. Sun, C. Vittoria, V. G. Harris
Room Temperature Magnetism In Semiconducting Films Of Zno Doped With Ferric Ions, S. D. Yoon, Y. J. Chen, D. Heiman, A. Yang, N. Sun, C. Vittoria, V. G. Harris
Vincent G. Harris
Films consisting of Zn₁₋ₓFeₓO were prepared by alternating-target laser ablation deposition. The Fe doping levels ranged from x=0.016 to 0.125 at. %. X-ray diffraction and energy dispersive x-ray spectroscopy measurements showed only (002n) reflections of the ZnO host and confirmation of the Fe concentration, respectively. For films grown on (001) Al₂O₃ at 300 K, room temperature average saturation magnetization, < 4πMs >, measured from superconducting quantum interference device (SQUID) hysteresis loops for x=0.125 ± 0.025 was 172 G. Although SQUID measurements were sensitive to the average value of the saturation magnetization, ferrimagnetic resonance measurements appeared to be sensitive only to the saturation …
Multiferroic Heterostructure Fringe Field Tuning Of Meander Line Microstrip Ferrite Phase Shifter, A. L. Geiler, S. M. Gillette, Y. Chen, J. Wang, Z. Chen, S. D. Yoon, P. He, J. Gao, C. Vittoria, V. G. Harris
Multiferroic Heterostructure Fringe Field Tuning Of Meander Line Microstrip Ferrite Phase Shifter, A. L. Geiler, S. M. Gillette, Y. Chen, J. Wang, Z. Chen, S. D. Yoon, P. He, J. Gao, C. Vittoria, V. G. Harris
Vincent G. Harris
Magnetic fringe fields emanating from a multiferroic heterostructure composite of Terfenol-D and lead magnesium niobate-lead titanate were utilized to actively tune a meander line microstrip ferrite phase shifter operating above ferrimagnetic resonance at C-band. Differential phase shifts of 65 degrees were measured when tuned with an applied voltage to the multiferroic heterostructure. This demonstration of magnetoelectric field generation provides an alternative approach to tuning broadband planar microwave magnetic devices where neither strain nor direct electromagnetic coupling is experienced between device and multiferroic transducer.
M-Type Barium Hexaferrite Synthesis And Characterization For Phase Shifter Applications, A. T. Wise, J. Rocks, D. E. Laughlin, M. E. Mchenry, S. D. Yoon, C. Vittoria, V. G. Harris
M-Type Barium Hexaferrite Synthesis And Characterization For Phase Shifter Applications, A. T. Wise, J. Rocks, D. E. Laughlin, M. E. Mchenry, S. D. Yoon, C. Vittoria, V. G. Harris
Vincent G. Harris
M-type barium hexaferrite films have been grown by liquid phase epitaxy and examined by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and conventional and Lorentz-mode transmission electron microscopy (TEM). These films exhibit a diamond chevron shaped "brick wall" microstructure with c-axis oriented hexaferrite platelets. The films are oriented with their c axes in-plane, and parallel to the M-plane sapphire substrate, and exhibit a 30 degrees rotation about the c axis with respect to the substrate. Rocking curves showed (20-20) and (22-40) FWHM values of 1.09 degrees and 1.56 degrees, respectively, for the thinner of two samples, and 0.31 degrees …
The Effect Of Boron Addition On The Atomic Structure And Microwave Magnetic Properties Of Fegab Thin Films, Jinsheng Gao, Aria Yang, Yajie Chen, J. P. Kirkland, Jing Lou, Nian X. Sun, Carmine Vittoria, Vincent G. Harris
The Effect Of Boron Addition On The Atomic Structure And Microwave Magnetic Properties Of Fegab Thin Films, Jinsheng Gao, Aria Yang, Yajie Chen, J. P. Kirkland, Jing Lou, Nian X. Sun, Carmine Vittoria, Vincent G. Harris
Vincent G. Harris
Varying amounts of boron were added to the host FeGa alloy to investigate its impact upon local atomic structure and magnetic and microwave properties. The impact of B upon the local atomic structure in FeGaB films was investigated by extended x-ray absorption fine structure (EXAFS) analysis. The EXAFS fitting results revealed a contraction of lattice parameters with the introduction of B. The Debye-Waller factor determined from EXAFS fitting increases as a function of boron addition and abruptly changes during the structural evolution from crystalline to amorphous that occurs near 9% B. Upon the onset of this transition the static and …
Magnetoelectric Effects In Composite Of Nanogranular Fe/Tio(2₋Δ) Films, S. D. Yoon, C. Vittoria, Y. N. Srivastava, A. Widom, V. G. Harris
Magnetoelectric Effects In Composite Of Nanogranular Fe/Tio(2₋Δ) Films, S. D. Yoon, C. Vittoria, Y. N. Srivastava, A. Widom, V. G. Harris
Vincent G. Harris
Employing a new experimental technique to measure magnetoelectric response functions, we have measured the magnetoelectric effect in composite films of nanogranular metallic iron in anatase titanium dioxide at temperatures below 50 K. A magnetoelectric resistance is defined as the ratio of a transverse voltage to bias current as a function of magnetic field. In contrast to the anomalous Hall resistance measured above 50 K, the magnetoelectric resistance below 50 K is significantly larger and exhibits an even symmetry with respect to magnetic field reversal H ->-H. The composite films are unique in terms of showing magnetoelectric effects at low …
Correlation Of Magnetic-Properties And Local Atomic-Structure Observed By Electron-Yield Exafs In Amorphous Co₇₄Fe₆B₁₅Si₅ Thin-Films, V. G. Harris, S. A. Oliver, W. B. Nowak, C. Vittoria, K. H. Kim, W. T. Elam
Correlation Of Magnetic-Properties And Local Atomic-Structure Observed By Electron-Yield Exafs In Amorphous Co₇₄Fe₆B₁₅Si₅ Thin-Films, V. G. Harris, S. A. Oliver, W. B. Nowak, C. Vittoria, K. H. Kim, W. T. Elam
Vincent G. Harris
Thin-film specimens of amorphous Co₇₄Fe₆B₁₅Si₅ were subjected to heat-treatment procedures followed by room-temperature magnetic and structural characterization in an effort to quantitatively correlate magnetic property changes to local atomic structure. Fourier transforms of electron-yield extended x-ray-absorption fine structure spectra show second and higher atomic shell ordering about transition-metal ions to occur at Tann ≈300°C. This ordering evolves to a body-centered atomic structure with heat treatments at higher temperatures. Accompanying this structural evolution is an expansion of the nearest-neighbor distance, disruption of the spin-wave-resonance spectra, and general deterioration of the soft magnetic properties.
Structural And Magnetic Properties Of Ball-Milled Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu Powders, Ashish K. Baraskar, Yajie Chen, Soack Dae Yoon, C. N. Chinnasamy, Nian Sun, Carmine Vittoria, Vincent G. Harris, Todd Heil, Matthew Willard
Structural And Magnetic Properties Of Ball-Milled Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu Powders, Ashish K. Baraskar, Yajie Chen, Soack Dae Yoon, C. N. Chinnasamy, Nian Sun, Carmine Vittoria, Vincent G. Harris, Todd Heil, Matthew Willard
Vincent G. Harris
Thick films of the Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu composition were synthesized via screen printing of the ball-milled ribbons of the above composition for possible use as planar inductors. The ribbons were obtained by rapid solidification. The resulting ribbon samples were annealed at 300 degrees C for 2 h to cause embrittlement. They were found to have soft magnetic properties (4πMs∽13 kG,ΔH ∽100 Oe, and Hc< 0.5 Oe). The brittle ribbons were ball milled using tungsten carbide vials and stainless steel balls in an inert atmosphere for various milling times. The sample milled for 10 h was found to have a 4πMs of about …
Alternating Target Laser Ablation Deposition Of High Quality Barium Hexaferrite Thin Films From Barium Monoferrite And Hematite Targets, A. L. Geiler, S. D. Yoon, Y. Chen, A. Yang, C. N. Chinnasamy, M. Geiler, V. G. Harris, C. Vittoria
Alternating Target Laser Ablation Deposition Of High Quality Barium Hexaferrite Thin Films From Barium Monoferrite And Hematite Targets, A. L. Geiler, S. D. Yoon, Y. Chen, A. Yang, C. N. Chinnasamy, M. Geiler, V. G. Harris, C. Vittoria
Vincent G. Harris
An optimized alternating target laser ablation deposition (ATLAD) technique has been developed to grow high quality barium hexaferrite (BaFe₁₂O₁₉) thin films on basal plane oriented sapphire(Al₂O₃) substrates from barium monoferrite (BaFe₂O₄) and hematite (α-Fe₂O₃) targets. Crystallographic and structural characterization results show that the films possess low c-axis dispersion of Δ ω=0.259 degrees and hexagonal terraced surface morphology. Saturation magnetization and uniaxial magnetic anisotropy field were determined to be consistent with reference data on high quality barium hexaferrite films and bulk single crystals grown by other techniques. Ferromagnetic resonance linewidth of 42 Oe was measured at 52 GHz by the shorted …
Bafe₁₂O₁₉ Thin Films Grown At The Atomic Scale From Bafe₂O₄ And Α-Fe₂O₃ Targets, A. L. Geiler, S. D. Yoon, Y. Chen, C. N. Chinnasamy, Z. Chen, M. Geiler, V. G. Harris, C. Vittoria
Bafe₁₂O₁₉ Thin Films Grown At The Atomic Scale From Bafe₂O₄ And Α-Fe₂O₃ Targets, A. L. Geiler, S. D. Yoon, Y. Chen, C. N. Chinnasamy, Z. Chen, M. Geiler, V. G. Harris, C. Vittoria
Vincent G. Harris
Hexagonal barium ferrite (BaFe₁₂O₁₉) thin films were grown at the atomic scale by alternating target laser ablation deposition (ATLAD) of orthorhombic BaFe₂O₄ and rhombohedral α-Fe₂O₃ on < 001 > Al₂O₃ substrates. Crystallographic, magnetic, and microwave properties of the ATLAD films were determined to be comparable with single crystal quality bulk and films of BaFe₁₂O₁₉ produced by other techniques. The ability to deposit high quality hexagonal ferrite thin films by utilizing multiple targets of different chemical compositions in the deposition routine provides unique opportunities to control the ionic distribution in the unit cell of this important class of ferrite materials.
Pulsed Laser Ablation Deposition Of Nanocrystalline Exchange-Coupled Ni₁₁Co₁₁Fe₆₇₋ₓzr₇B₄Cux (X=0,1) Films For Planar Inductor Applications, Ashish K. Baraskar, Soack Dae Yoon, Anton Geiler, Aria Yang, C. N. Chinnasamy, Yajie Chen, Nian Sun, Carmine Vittoria, Ramasis Goswami, Matthew Willard, Vincent G. Harris
Pulsed Laser Ablation Deposition Of Nanocrystalline Exchange-Coupled Ni₁₁Co₁₁Fe₆₇₋ₓzr₇B₄Cux (X=0,1) Films For Planar Inductor Applications, Ashish K. Baraskar, Soack Dae Yoon, Anton Geiler, Aria Yang, C. N. Chinnasamy, Yajie Chen, Nian Sun, Carmine Vittoria, Ramasis Goswami, Matthew Willard, Vincent G. Harris
Vincent G. Harris
Nanocrystalline films of the Ni₁₁Co₁₁Fe₆₇₋ₓZr₇B₄Cux (x=0,1) composition were deposited on fused quartz substrates by pulsed laser deposition. For the films ofNi₁₁Co₁₁Fe₆₆Zr₇B₄Cu, the bcc grain size ranged from 5 to 8 nm in the films deposited at substrate temperatures from ambient to 300°C. Films grown at a substrate temperature of 300°C were found to have optimal magnetic properties including minima in the coercivity and ferromagnetic resonance (FMR) linewidth. The magnetic characterization studies showed coercivity Hc < 5 Oe, 4πMs ∽16 kG, and in-plane uniaxial anisotropy field (HA)∽25-30 Oe. The ferromagnetic resonance linewidth was measured to be 34 Oe and zero magnetic field …
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.
Magnetic And Microwave Properties Of Cofe/Ptmn/Cofe Multilayer Films, C. I. Pettiford, A. Zeltser, S. D. Yoon, V. G. Harris, C. Vittoria, N. X. Sun
Magnetic And Microwave Properties Of Cofe/Ptmn/Cofe Multilayer Films, C. I. Pettiford, A. Zeltser, S. D. Yoon, V. G. Harris, C. Vittoria, N. X. Sun
Vincent G. Harris
CoFe/PtMn/CoFe films were deposited on seed layers of Ru or NiFeCr with CoFe film compositions being either Co-10 at. %Fe or Co-16 at. %Fe. Eight periods of the CoFe/PtMn/CoFe trilayers were also prepared. The magnetic properties and ferromagnetic resonance (FMR) of these films were characterized with vibrating-sample magnetometer, and field-sweep FMR system at X band (∽9.5 GHz). The Ru-seeded CoFe/PtMn/CoFe sandwich films show excellent magnetic softness with a low hard axis coercivity of 2-4 Oe, an easy axis Mr/Ms of >98%, and a significantly enhanced in-plane anisotropy of 57-123 Oe when CoFe layer thickness is above 200 Å. Contrary to …
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 …
Structure And Magnetism Of Nanocrystalline Exchange-Coupled (Ni₀.₆₇Co₀.₂₅Fe₀.₀₈)₈₉₋ₓzr₇B₄Cuₓ (X=0,1) Films, S. Joshi, S. D. Yoon, A. Yang, N. X. Sun, C. Vittoria, V. G. Harris, R. Goswami, M. Willard, N. Shi
Structure And Magnetism Of Nanocrystalline Exchange-Coupled (Ni₀.₆₇Co₀.₂₅Fe₀.₀₈)₈₉₋ₓzr₇B₄Cuₓ (X=0,1) Films, S. Joshi, S. D. Yoon, A. Yang, N. X. Sun, C. Vittoria, V. G. Harris, R. Goswami, M. Willard, N. Shi
Vincent G. Harris
Structural and magnetic characterizations of nanocrystalline films of (Ni₀.₆₇Co₀.₂₅Fe₀.₀₈)₈₉₋ₓZr₇B₄Cuₓ (x=0,1) alloys are reported. The films were grown on quartz substrates using pulsed laser deposition from homogeneous targets of the above compositions at substrate temperatures ranging from ambient to 600°C. Structural properties were measured by x-ray diffraction, atomic force microscopy, and transmission electron microscopy, whereas the magnetic properties were measured by vibrating sample magnetometry and ferromagnetic resonance. The resulting films exist as a two phase alloy with face-centered-cubic metallic grains suspended in an amorphous matrix. For both the x=1 and x=0 alloys, the softest magnetic properties (coercivity Hc < 0.5 Oe, 4πMs …
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.
Cation Engineering Of Cu-Ferrite Films Deposited By Alternating Target Laser Ablation Deposition, Aria Yang, Zhaohui Chen, Shaheen M. Islam, Carmine Vittoria, V. G. Harris
Cation Engineering Of Cu-Ferrite Films Deposited By Alternating Target Laser Ablation Deposition, Aria Yang, Zhaohui Chen, Shaheen M. Islam, Carmine Vittoria, V. G. Harris
Vincent G. Harris
Epitaxial copper ferrite thin films were deposited on MgO substrates by the alternating target laser ablation deposition method. A series of films was studied to explore the impact of oxygen operating pressure, substrate temperature, and the ratio of laser shots incident on each target upon the magnetic, structural, and atomic structural properties. The highest saturation magnetization, 2800 G, was achieved at a 90 mTorr oxygen pressure and at 650 degrees C for the substrate temperature. This value is 65% higher than the room temperature magnetization for bulk equilibrium samples. The inversion parameter was measured by extended x-ray absorption fine structure …
Single Crystal Fe Films Grown On Ge(001) Substrates By Magnetron Sputtering, J. Lou, A. Daigle, L. Chen, Y. Q. Wu, V. G. Harris, C. Vittoria, N. X. Sun
Single Crystal Fe Films Grown On Ge(001) Substrates By Magnetron Sputtering, J. Lou, A. Daigle, L. Chen, Y. Q. Wu, V. G. Harris, C. Vittoria, N. X. Sun
Vincent G. Harris
Single crystal Fe films were grown on Ge (001) substrates by using dc magnetron sputtering. It was found that the microstructures and magnetic properties of Fe films on Ge substrates were strongly dependent upon the substrate temperature during the deposition process. There existed a narrow substrate temperature window of 125 ± 25°C for achieving single crystal Fe film on Ge. Lower substrate temperature led to polycrystalline Fe films due to limited mobility of Fe atoms, while higher substrate temperatures resulted in amorphous Fe-Ge alloy due to severe interdiffusion.
A Quantitative Model For The Nonlinear Response Of Fluxgate Magnetometers, A. L. Geiler, V. G. Harris, C. Vittoria, N. X. Sun
A Quantitative Model For The Nonlinear Response Of Fluxgate Magnetometers, A. L. Geiler, V. G. Harris, C. Vittoria, N. X. Sun
Vincent G. Harris
An analytical nonlinear hysteresis model was developed to describe the hysteresis loops of different magnetic materials, which was capable of fitting Permalloy films as an example. As a case study this model was applied in the sensitivity analysis of the fluxgate magnetometers where accurately capturing the nonlinear behavior of the magnetic core is crucial. Straightforward analytical equation of the output voltage signal as well as its harmonic decomposition was obtained for the fluxgate magnetometer as a function of hysteresis loop parameters. Sensitivity values predicted by the model were found to be consistent with the measured values published previously. The model …