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- BaFe₂O₄ (2)
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Articles 1 - 30 of 109
Full-Text Articles in Engineering
Ba-Hexaferrite Films For Next Generation Microwave Devices, Vincent Girard Harris (1962-), Zhaohui Chen, Yajie Chen, Soack Dae Yoon, Tomokuza Sakai, Anton Geiler, Aria Fan Yang, Yongxue He, Katherine S. Ziemer, Nian X. Sun, C. Vittoria
Ba-Hexaferrite Films For Next Generation Microwave Devices, Vincent Girard Harris (1962-), Zhaohui Chen, Yajie Chen, Soack Dae Yoon, Tomokuza Sakai, Anton Geiler, Aria Fan Yang, Yongxue He, Katherine S. Ziemer, Nian X. Sun, C. Vittoria
Carmine Vittoria
Next generation magnetic microwave devices require ferrite films to be thick (>300 μm), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands. Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD), liquid-phase epitaxy, and screen printing. These techniques are compared and contrasted as to their suitability for microwave materials processing and industrial production. Recent advances include the PLD growth of BaM on wide-band-gap semiconductor substrates and the development of thick, self-biased, low-loss BaM films by screen printing.
Ba-Hexaferrite Films For Next Generation Microwave Devices, Vincent Girard Harris (1962-), Zhaohui Chen, Yajie Chen, Soack Dae Yoon, Tomokuza Sakai, Anton Geiler, Aria Fan Yang, Yongxue He, Katherine S. Ziemer, Nian X. Sun, C. Vittoria
Ba-Hexaferrite Films For Next Generation Microwave Devices, Vincent Girard Harris (1962-), Zhaohui Chen, Yajie Chen, Soack Dae Yoon, Tomokuza Sakai, Anton Geiler, Aria Fan Yang, Yongxue He, Katherine S. Ziemer, Nian X. Sun, C. Vittoria
Carmine Vittoria
Next generation magnetic microwave devices require ferrite films to be thick (>300 μm), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands. Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD), liquid-phase epitaxy, and screen printing. These techniques are compared and contrasted as to their suitability for microwave materials processing and industrial production. Recent advances include the PLD growth of BaM on wide-band-gap semiconductor substrates and the development of thick, self-biased, low-loss BaM films by screen printing.
Ferromagnetic Resonance Measurements On Epitaxial Grown Fe/Znse And Co/Znse Films On Gaas Substrates, S. A. Oliver, C. Vittoria, J. J. Krebs, B. T. Jonker, G. A. Prinz
Ferromagnetic Resonance Measurements On Epitaxial Grown Fe/Znse And Co/Znse Films On Gaas Substrates, S. A. Oliver, C. Vittoria, J. J. Krebs, B. T. Jonker, G. A. Prinz
Carmine Vittoria
Ferromagnetic resonance (FMR) measurements have been performed over a broad frequency range on epitaxial films of Co and bcc α‐Fe grown onto epilayers of ZnSe by molecular‐beam‐epitaxy techniques on (001) and (110) GaAs substrates. In‐plane and perpendicular FMR results were used in deducing the magnetic parameters and spin‐wave resonance (SWR) dispersion of the films. The magnetic parameters deduced for Fe films agree with previous results obtained on the (001) Fe/ZnSe film. Well‐resolved SWR modes were observed in the Fe/ZnSe films, allowing extraction of the exchange stiffness constant. Few spin‐wave excitations were observed for the Co/ZnSe films. Both (110) Fe/ZnSe and …
Magnetic Anisotropy And Crystalline Texture In Bao(Fe₂O₃)₆ Thin Films Deposited On Gan/Al₂O₃, Paul R. Ohodnicki, K. Y. Goh, Yuranan Hanlumyuang, K. Ramos, Michael E. Mchenry, Zhuhua Cai, Katherine Ziemer, Hadis Morkoc, Necmi Biyikli, Zhaohui Chen, C. Vittoria, Vincent Girard Harris (1962-)
Magnetic Anisotropy And Crystalline Texture In Bao(Fe₂O₃)₆ Thin Films Deposited On Gan/Al₂O₃, Paul R. Ohodnicki, K. Y. Goh, Yuranan Hanlumyuang, K. Ramos, Michael E. Mchenry, Zhuhua Cai, Katherine Ziemer, Hadis Morkoc, Necmi Biyikli, Zhaohui Chen, C. Vittoria, Vincent Girard Harris (1962-)
Carmine Vittoria
BaO(Fe₂O₃)₆ (BaM) thin films were deposited by pulsed laser deposition on GaN/Al₂O₃ substrates. A pole figure obtained from the (006) reflection indicated that ~81% of the film volume had the c axis tilted less than 5° from the film normal. A low anisotropy field was inferred from vector coil vibrating sample magnetometer (VVSM) measurements. The reduction in Hₐ from literature values and a two-step switching of the easy axis magnetization is postulated to result from interdiffusion and misalignment effects. To alleviate interdiffusion and to improve the c-axis alignment, experiments were repeated with lower deposition temperatures, thinner films, and MgO buffer …
Resonance Damping In Ferromagnets And Ferroelectrics, Allan Widom, Somu Sivasubramanian, Carmine Vittoria, S. Yoon, Yogendra N. Srivastava
Resonance Damping In Ferromagnets And Ferroelectrics, Allan Widom, Somu Sivasubramanian, Carmine Vittoria, S. Yoon, Yogendra N. Srivastava
Carmine Vittoria
The phenomenological equations of motion for the relaxation of ordered phases of magnetized and polarized crystal phases can be developed in close analogy with one another. For the case of magnetized systems, the driving magnetic field intensity toward relaxation was developed by Gilbert. For the case of polarized systems, the driving electric field intensity toward relaxation was developed by Khalatnikov. The transport times for relaxation into thermal equilibrium can be attributed to viscous sound wave damping via magnetostriction for the magnetic case and electrostriction for the polarization case.
The Effects Of Room Temperature Aging Upon The Magnetic Properties Of Ba-Hexaferrite Films Grown On 6h-Sic Substrates, Zhaohui Chen, Zhuhua Cai, Aria Fan Yang, Katherine S. Ziemer, C. Vittoria, Vincent Girard Harris (1962-)
The Effects Of Room Temperature Aging Upon The Magnetic Properties Of Ba-Hexaferrite Films Grown On 6h-Sic Substrates, Zhaohui Chen, Zhuhua Cai, Aria Fan Yang, Katherine S. Ziemer, C. Vittoria, Vincent Girard Harris (1962-)
Carmine Vittoria
The successes of making acceptable magnetic properties BaM films by different techniques based on pulsed laser deposition were reported in the past years. The key was to introduce a proper buffer layer to promote two dimensional growths on these semiconductor material substrates. After years, we go back to characterize these samples made by different processings. The purpose of this experiment is to explore the role of the buffer layers especially with the time dependence and thus demonstrate our film suitable for the potential future application. These samples are characterized by scanning electron microscopy, x-ray diffraction, and vibrating sample magnetometry comparing …
Properties Of Pulsed Laser Deposited Scandium-Doped Barium Hexaferrite Films, S. A. Oliver, M. L. Chen, C. Vittoria, P. Lubitz
Properties Of Pulsed Laser Deposited Scandium-Doped Barium Hexaferrite Films, S. A. Oliver, M. L. Chen, C. Vittoria, P. Lubitz
Carmine Vittoria
The properties of thin films of BaScₓFe₁₂₋ₓO₁₉ (x = 0.4) were determined by structural and magnetic measurements. Films were deposited by pulsed laser ablation deposition onto c-plane sapphire at oxygen pressures between 10 and 100 mTorr. X-ray diffraction measurements showed all films to be single-phase c-axis oriented hexaferrites with expanded c-axis lattice constants compared to x = 0 films. Magnetometry measurements showed that all films had the easy axis (c-axis) normal to the film plane, with a mean saturation magnetization value of 3.8 kG. The mean uniaxial anisotropy field value was 10.6 kOe. This ability to adjust the uniaxial anisotropy …
Nonreciprocal Coupling Structure Of Dielectric Wave-Guides, P. Kwan, C. Vittoria, J. Proske
Nonreciprocal Coupling Structure Of Dielectric Wave-Guides, P. Kwan, C. Vittoria, J. Proske
Carmine Vittoria
M-type hexagonal ferrites have been incorporated in a coupled dielectric image guides structure for nonreciprocal microwave circuits design. Two different field configurations have been considered in this paper: for case I the c axis of the ferrite materials was aligned along the direction of propagation; for case II the c axis was aligned in the transverse direction. Electromagnetic wave scattering S parameters of the device were measured for an external biasing magnetic field applied parallel and perpendicular to the c axis of the ferrite slab. We have observed nonreciprocal microwave effects in the ferromagnetic resonance regime as a result of …
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
Carmine Vittoria
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 …
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
Carmine Vittoria
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) …
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
Carmine Vittoria
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 …
Screen Printed Thick Self-Biased, Low-Loss, Barium Hexaferrite Films By Hot-Press Sintering, Yajie Chen, Tomokazu Sakai, Taiyang Chen, Soack D. Yoon, Carmine Vittoria, Vincent G. Harris
Screen Printed Thick Self-Biased, Low-Loss, Barium Hexaferrite Films By Hot-Press Sintering, Yajie Chen, Tomokazu Sakai, Taiyang Chen, Soack D. Yoon, Carmine Vittoria, Vincent G. Harris
Carmine Vittoria
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 …
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
Carmine Vittoria
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 …
Bulk And Surface Retarded Modes In Multilayered Structures - Antiparallel Magnetization, H. How, C. Vittoria
Bulk And Surface Retarded Modes In Multilayered Structures - Antiparallel Magnetization, H. How, C. Vittoria
Carmine Vittoria
The wave dispersion relations of the mixed polariton-photon modes propagating within the bulk and along the surface of a semi-infinite magnetic/nonmagnetic layered structure with an alternating arrangement of the magnetization are calculated. The magnetic layers are magnetized to saturation along the uniaxial anisotropy axis, and the waves are considered to propagate transverse to this axis. The results are contrasted with those calculated for a layered structure in which the magnetization in each layer is parallel to each other. For the antiparallel case there evolve modes of wave propagation which assume different dispersion forms when compared to the parallel case. In …
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
Carmine Vittoria
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
Carmine Vittoria
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
Carmine Vittoria
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 …
Magnetic-Resonance Experiments On Ion-Beam Sputtered (100) Fe Films, S. A. Oliver, C. Vittoria, E. Schloemann, H. J. Vanhook, R. W. Tustison
Magnetic-Resonance Experiments On Ion-Beam Sputtered (100) Fe Films, S. A. Oliver, C. Vittoria, E. Schloemann, H. J. Vanhook, R. W. Tustison
Carmine Vittoria
Ferromagnetic resonance (FMR) measurements have been performed on single-crystal Fe films, produced by ion beam sputtering techniques on GaAs substrates. In-plane FMR results over the frequency range 0.1-20.0 GHz were obtained by a slot line technique. The magnetic parameters deduced from these measurements are comparable to bulk Fe. In-plane angular variation reveals a negligible uniaxial anisotropy contribution to the magnetic anisotropy energy. Spin-wave excitations were observed in 9.5-GHz cavity measurements, and are found to obey the n2 law. The exchange stiffness constant is found to be somewhat larger than seen in other epitaxial Fe films. These results show that epitaxial …
Surface Retarded Modes In Multilayered Structures – Parallel Magnetization, H. How, C. Vittoria
Surface Retarded Modes In Multilayered Structures – Parallel Magnetization, H. How, C. Vittoria
Carmine Vittoria
The wave dispersion relations of the mixed polariton-photon modes along the surface of a semi-infinite layered structure consisting of alternating magnetic and nonmagnetic films are calculated. The magnetic films are magnetized to saturation by an external field parallel to the film plane and perpendicular to the wave propagation direction. Three different types of surpace modes are found and discussed. the surface-surface-type and (lower) surface-bulk-type modes can exist in a general layered structure which, when propogating in the positive k direction, corresponds in magnetostatic limit to those surface modes found by Camley et al. For negative k propagation of surface-surface-type modes, …
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
Carmine Vittoria
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
Carmine Vittoria
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
Carmine Vittoria
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 …
Ferrimagnetic Resonance Lineshape Asymmetry Due To Suhl Instabilities, P. Dorsey, J. B. Sokoloff, C. Vittoria
Ferrimagnetic Resonance Lineshape Asymmetry Due To Suhl Instabilities, P. Dorsey, J. B. Sokoloff, C. Vittoria
Carmine Vittoria
We present calculations of the ferrimagnetic resonance lineshapes resulting from second order Suhl instabilities for thin films and spheres. We find that whereas a spherical sample has a lineshape which is symmetrical around the resonant frequency, a thin film has an asymmetrical lineshape. The calculations are in agreement with measurements that we have performed of the lineshape as a function of input power for thin film samples of both barium ferrite and yttrium iron garnet. When the magnetic field direction is changed from perpendicular to parallel to the film plane, the asymmetry of the lineshape at magnetic resonance changes in …
Magnetic And Microwave Magnetic Properties Of Barium Hexaferrite Permanent Magnet Films Having The C-Axis In The Film Plane, S. D. Yoon, C. Vittoria, S. A. Oliver
Magnetic And Microwave Magnetic Properties Of Barium Hexaferrite Permanent Magnet Films Having The C-Axis In The Film Plane, S. D. Yoon, C. Vittoria, S. A. Oliver
Carmine Vittoria
Thick (1-14 μm) films of ferrimagnetic barium hexaferrite (BaFe₁₂O₁₉ or BaM) having the c-axis ([0001]) in the film plane were deposited by pulsed laser deposition onto a-plane (1120) sapphire (Al₂O₃) substrates, and were found to have a (1010) orientation. Torque and magnetization measurements show these films are permanent magnets with easy magnetization direction in the plane of the film. Ferrimagnetic resonance (FMR) spectra exhibited linewidths of 1.00-1.40 kOe, where low-field FMR measurements do not show uniform mode broadening due to the formation of multiple domains. All film parameters were affected by the large stress present in these films due to …
Ferromagnetic-Resonance In Magnetic Multilayer Structures, S. W. Mcknight, C. Vittoria
Ferromagnetic-Resonance In Magnetic Multilayer Structures, S. W. Mcknight, C. Vittoria
Carmine Vittoria
We have calculated the FMR line shape for magnetic multilayer structures of alternating iron and iron-alloy layers. The model assumes abrupt interfaces and that spins on adjacent layers are ferromagnetically coupled with an exchange constant A₁₂. The surface magnetic anisotropy fields are set to zero in our calculations. As A₁₂ is increased, satellite lines in the surface impedance split off from the ferromagnetic resonance main lines of the component materials. The number of satellites is one more than the number of layered pairs. The position and strength of these lines is found to be dependent on the relative layer thicknesses …
High-Sensitivity Ferromagnetic Resonance Measurements On Micrometer-Sized Samples, S. Zhang, S. A. Oliver, N. E. Israeloff, C. Vittoria
High-Sensitivity Ferromagnetic Resonance Measurements On Micrometer-Sized Samples, S. Zhang, S. A. Oliver, N. E. Israeloff, C. Vittoria
Carmine Vittoria
Ferromagnetic resonance measurements were taken on a 4 μm diam disk using a planar microwave transmission line device. The absorption modes of a sample placed on this devise can be measured by monitoring the microwave power transmitted across the device while a swept magnetic field varies the sample absorption through resonance. Results for the disk, which was etched from a 105 nm thick amorphous Fe₈₀B₁₅Si₅ film, followed the Kittel model over the frequency range from 2 to 20 GHz, in agreement with parameters measured on 5 mm diam disks by a microwave cavity. These results indicate the device has a …
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
Carmine Vittoria
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
Carmine Vittoria
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 …
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
Carmine Vittoria
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 …
Oriented Y-Type Hexaferrites For Ferrite Device, M. Obol, X. Zuo, C. Vittoria
Oriented Y-Type Hexaferrites For Ferrite Device, M. Obol, X. Zuo, C. Vittoria
Carmine Vittoria
We have developed a technique to orient particles of Y-type hexaferrite in which the c axis of the particles is oriented perpendicular to a plane. Disks of oriented Ba₂MnZnFe₁₂O₂₂ particles were characterized in static and dynamic field excitations and exhibited the following properties: 4πMs=2300 G, Ha=9500 G, 4πMeff=4πMs+Ha=11800 G, and Hc=60 Oe. The ferrimagnetic resonance linewidth at 27 GHz measured to be 350 Oe and the g factor approximately equal to 2. The magnetic parameters of the oriented particles were very similar to the bulk parameters previously published.