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Articles 1 - 30 of 92
Full-Text Articles in Engineering
A Five-Level Three-Phase Hybrid Cascade Multilevel Inverter Using A Single Dc Source For A Pm Synchronous Motor Drive, John N. Chiasson, Burak Ozpineci, Leon M. Tolbert
A Five-Level Three-Phase Hybrid Cascade Multilevel Inverter Using A Single Dc Source For A Pm Synchronous Motor Drive, John N. Chiasson, Burak Ozpineci, Leon M. Tolbert
Burak Ozpineci
The interest here is in using a single DC power source to construct a 3-phase 5-level cascade multilevel inverter to be used as a drive for a PM traction motor. The 5-level inverter consists of a standard 3-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg, which use a capacitor as a DC source. It is shown that one can simultaneously maintain the regulation of the capacitor voltage while achieving an output voltage waveform which is 25% higher than that obtained using a standard 3-leg inverter by itself.
Pre-Amplifiers For A 15-Tesla Magnetic Resonance Imager, Chin-Leong Lim, Peter Serano, Jerome L. Ackerman
Pre-Amplifiers For A 15-Tesla Magnetic Resonance Imager, Chin-Leong Lim, Peter Serano, Jerome L. Ackerman
Chin-Leong Lim
High-field magnetic resonance imagers (MRI) give better signal-to-noise ratio (SNR) and image contrast. However clinical MRIs are currently limited to 3 Tesla (T) magnetic field strength. To create an uncommon 15 T scanner for research use, we evaluated several low-cost, intended for wireless communication, GaAs enhancement-mode pseudomorphic high electron mobility transistors (ePHEMT) in the critical preamplifier slot. This paper reports the experimental results that were obtained at both module and system levels. When evaluated in our prototype 15 T scanner front-end’s preamplifier slot, the candidate devices’ sub 1dB noise figures enabled image SNR ~ 110 in a water phantom (test …
Limiting And Transient Performances Of A Low Loss Pin-Schottky Limiter, Chin-Leong Lim
Limiting And Transient Performances Of A Low Loss Pin-Schottky Limiter, Chin-Leong Lim
Chin-Leong Lim
The main cause of loss in the PIN-Schottky limiter is the diodes’ parasitic capacitances. Techniques to counter the parasitic capacitances include using bare chip, air cavity packaging, diode stacking, mesa construction, isolating the Schottky diode from the signal path and connecting the diodes to a low impedance node. But the aforementioned techniques either sacrifice cost, manufacturability, size, performances or thermal ruggedness. To reduce loss in the PIN-Schottky limiter, we re-configured its parasitics into a low pass ladder network. This paper reports on the new configuration’s changed large signal and transient performances. We observed improved isolation at 0.9 and 2.4 GHz, …
Computational Aspects Of The Three-Dimensional Feature-Scale Simulation Of Silicon-Nanowire Field-Effect Sesnsors For Dna Detection, Clemens Heitzinger, Gerhard Klimeck
Computational Aspects Of The Three-Dimensional Feature-Scale Simulation Of Silicon-Nanowire Field-Effect Sesnsors For Dna Detection, Clemens Heitzinger, Gerhard Klimeck
Gerhard Klimeck
In recent years DNA-sensors, and generally biosensors, with semiconducting transducers were fabricated and characterized. Although the concept of so-called BioFETs was proposed already two decades ago, its realization has become feasible only recently due to advances in process technology. In this paper a comprehensive and rigorous approach to the simulation of silicon-nanowire DNAFETs at the feature-scale is presented. It allows to investigate the feasibility of single-molecule detectors and is used to elucidate the performance that can be expected from sensors with nanowire diameters in the deca-nanometer range. Finally the computational challenges for the simulation of silicon-nanowire DNAsensors are discussed.
Low Rank Approximation Method For Efficient Green's Function Calculation Of Dissipative Quantum Transport, Lang Zeng, Yu He, Michael Povolotskyi, Xiao Yan Liu, Gerhard Klimeck, Tillmann Kubis
Low Rank Approximation Method For Efficient Green's Function Calculation Of Dissipative Quantum Transport, Lang Zeng, Yu He, Michael Povolotskyi, Xiao Yan Liu, Gerhard Klimeck, Tillmann Kubis
Gerhard Klimeck
In this work, the low rank approximation concept is extended to the non-equilibrium Green’s function (NEGF) method to achieve a very efficient approximated algorithm for coherent and incoherent electron transport. This new method is applied to inelastic transport in various semiconductor nanodevices. Detailed benchmarks with exact NEGF solutions show (1) a very good agreement between approximated and exact NEGF results, (2) a significant reduction of the required memory, and (3) a large reduction of the computational time (a factor of speed up as high as 150 times is observed). A non-recursive solution of the inelastic NEGF transport equations of a …
Experimental And Theoretical Study Of Polarization-Dependent Optical Transitions In Inas Quantum Dots At Telecommunication-Wavelengths (1300-1500 Nm), Muhammad Usman, Susannah Heck, Edmund Clarke, Peter Spencer, Hoon Ryu, Ray Murray, Gerhard Klimeck
Experimental And Theoretical Study Of Polarization-Dependent Optical Transitions In Inas Quantum Dots At Telecommunication-Wavelengths (1300-1500 Nm), Muhammad Usman, Susannah Heck, Edmund Clarke, Peter Spencer, Hoon Ryu, Ray Murray, Gerhard Klimeck
Gerhard Klimeck
observed, in contrast to recent reports for single QDJOURNAL OF APPLIED PHYSICS 109, 104510 (2011)The design of some optical devices, such as semiconductor optical amplifiers for telecommunication applications, requires polarization-insensitive optical emission at long wavelengths (1300–1550 nm). Self-assembled InAs/GaAs quantum dots (QDs) typically exhibit ground state optical emissions at wavelengths shorter than 1300 nm with highly polarization-sensitive characteristics, although this can be modified by the use of low growth rates, the incorporation of strain-reducing capping layers, or the growth of closely-stacked QD layers. Exploiting the strain interactions between closely stacked QD layers also affords greater freedom in the choice of …
Computing Entries Of The Inverse Of A Sparse Matrix Using The Find Algorithm, S Li, Gerhard Klimeck, E Darve
Computing Entries Of The Inverse Of A Sparse Matrix Using The Find Algorithm, S Li, Gerhard Klimeck, E Darve
Gerhard Klimeck
An accurate and efficient algorithm, called fast inverse using nested dissection (FIND). for computing non-equilibrium Green's functions (NEGF) for nanoscale transistors has been developed and applied in the simulation of a novel dual-gate metal-oxide-semi conductor field-effect transistor (MOSFET) device structure. The method is based on the algorithm of nested dissection. A graph of the matrix is constructed and decomposed using a tree structure. An upward and downward traversal of the tree yields significant performance improvements for both the speed and memory requirements, compared to the current state-of-the-art recursive methods for NEGF. This algorithm is quite general and can be applied …
Design Concepts Of Terahertz Quantum Cascade Lasers: Proposal For Terahertz Laser Efficiency Improvements, Tillmann Kubis, Saumitra Raj Mehrotra, Gerhard Klimeck
Design Concepts Of Terahertz Quantum Cascade Lasers: Proposal For Terahertz Laser Efficiency Improvements, Tillmann Kubis, Saumitra Raj Mehrotra, Gerhard Klimeck
Gerhard Klimeck
Conceptual disadvantages of typical resonant phonon terahertz quantum cascade lasers THz-QCLs are analyzed. Alternative designs and their combination within a concrete device proposal are discussed to improve the QCL performance. The improvements are 1 indirect pumping of the upper laser level, 2 diagonal optical transitions, 3 complete electron thermalization, and 4 materials with low effective electron masses. The nonequilibrium Green’s function method is applied to predict stationary electron transport and optical gain. The proposed THz-QCL shows a higher optical gain, a lower threshold current, and a higher operation temperature. Alloy disorder scattering can worsen the QCL performance.
Probabilistic Verification Of Coordinated Multi-Robot Missions, Sagar J. Chaki, Joseph A. Giampapa
Probabilistic Verification Of Coordinated Multi-Robot Missions, Sagar J. Chaki, Joseph A. Giampapa
Joseph Andrew Giampapa
Robots are increasingly used to perform a wide variety of tasks, especially those involving dangerous or inaccessible locations. As the complexity of such tasks grow, robots are being deployed in teams, with complex coordination schemes aimed at maximizing the chance of mission success. Such teams operate under inherently uncertain conditions -- the robots themselves fail, and have to continuously adapt to changing environmental conditions. A key challenge facing robotic mission designers is therefore to construct a mission -- i.e., specify number and type of robots, number and size of teams, coordination and planning mechanisms etc. -- so as to maximize …
Efficient Processing Of System Scenarios In Statistical And Machine Learning Studies For Power System Operational And Investment Planning, Venkat Kumar Krishnan
Efficient Processing Of System Scenarios In Statistical And Machine Learning Studies For Power System Operational And Investment Planning, Venkat Kumar Krishnan
Venkat Kumar Krishnan
Power System security assessment and the associated planning studies are becoming more and more complex with ever increasing uncertainties in all time horizons. An effective means of performing operational and investment planning studies of network limitations associated with static or dynamic post-disturbance performance problems has been to take a Monte Carlo simulation based approach. The approach harnesses computing power to develop a database of post-contingency response over a wide range of different operating conditions, and then apply statistical or machine learning methods to extract useful planning and operational information from the database. Key to the machine learning based planning approach …
Distribution Free Prediction Interval For Uncertainty Quantification In Remaining Useful Life Prediction, Huimin Chen
Distribution Free Prediction Interval For Uncertainty Quantification In Remaining Useful Life Prediction, Huimin Chen
Huimin Chen
Remaining useful life (RUL) prediction is an important component for system health monitoring and prognosis. Ideally, one expects the prediction algorithm to provide the complete distribution of the RUL prediction over time taking various uncertainties into account. However, the dynamic model being used to characterize state estimation and future loading uncertainties is often simplified through various approximations, leading to non-credible predicted distribution. Nevertheless, certain algorithm may only provide a point estimate of the RUL, making it difficult to quantify the uncertainty of the prediction. In this paper, we focus on interval prediction with high probability that guarantees finite sample validity …
Energy Modeling Of Processors Inwireless Sensor Networks Based On Petri Nets, Ali Shareef, Yifeng Zhu
Energy Modeling Of Processors Inwireless Sensor Networks Based On Petri Nets, Ali Shareef, Yifeng Zhu
Yifeng Zhu
Power minimization is a serious issue in wireless sensor networks to extend the lifetime and minimize costs. However, in order to gain an accurate understanding of issues regarding power minimization, modeling techniques capable of accurately predicting energy consumption are needed. This paper demonstrates that Petri nets are a viable option of modeling a processor. In fact, this paper shows that the Petri nets’ accuracy surpasses a Markov model utilizing supplementary variables to account for constant delays.
Localization Using Extended Kalman Filters In Wireless Sensor Networks, Ali Shareef, Yifeng Zhu
Localization Using Extended Kalman Filters In Wireless Sensor Networks, Ali Shareef, Yifeng Zhu
Yifeng Zhu
Introduction: Localization arises repeatedly in many location-aware applications such as navigation, autonomous robotic movement, and asset tracking. Analytical localization methods include triangulation and trilateration. Triangulation uses angles, distances, and trigonometric relationships to locate an object. Trilateration, on the other hand, uses only distance measurements to identify the position of the target.
Efficient Superposition Of Communication And Radar Waveforms (Raytheon), Anton Frolenkov, Vidie Pong, Sasha Sproch, Amy Whitcombe
Efficient Superposition Of Communication And Radar Waveforms (Raytheon), Anton Frolenkov, Vidie Pong, Sasha Sproch, Amy Whitcombe
Sasha A Sproch
The goal of the Raytheon-Olin SCOPE team was to identify pairs of communication and radar waveforms that could be superimposed through a single nonlinear amplifier while still fulfilling primary communications and radar functions. The team investigated candidate performance using hardware experimentation and industry-standard simulation. The results of this study begin to define the conditions for successful simultaneous communications and radar transmission through a single non-linear amplifier.
Balanced Uhf Lna Simplifies Cell Towers, Chin-Leong Lim
Balanced Uhf Lna Simplifies Cell Towers, Chin-Leong Lim
Chin-Leong Lim
Cellular basestations' low noise amplifiers (LNA) must have input impedances that are closely matched to the antennas. Unfortunately, the amplifier devices cannot be conjugate matched without sacrificing their noise performances. Current solutions such as the isolator and the balanced LNA can satisfactorily solve the matching problem but at the expense of increased cost, weight and size. On the other hand, the confined space atop cellular towers makes the current solutions unattractive. To shrink the balanced LNA for cellular infrastructure service, we pair a highly integrated dual-amplifier MMIC with miniature multilayer couplers. This MMIC also achieves the distinction of being the …
Brief Comparison Between 8051 And Avr, Ata Jahangir Moshayedi
Brief Comparison Between 8051 And Avr, Ata Jahangir Moshayedi
Ata Jahangir Moshayedi
Brief comparison between 8051 and AVR
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
Nian X. Sun
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 …
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
Nian X. Sun
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.
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
Nian X. Sun
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 …
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
Nian X. Sun
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 …
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
Nian X. Sun
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 …
Microwave, Magnetic, And Structural Properties Of Nanocrystalline Exchange-Coupled Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu₁ Films For High Frequency Applications, S. D. Yoon, A. K. Baraskar, A. Geiler, A. Yang, C. Pettiford, N. X. Sun, R. Goswami, M. A. Willard, C. Vittoria, V. G. Harris
Microwave, Magnetic, And Structural Properties Of Nanocrystalline Exchange-Coupled Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu₁ Films For High Frequency Applications, S. D. Yoon, A. K. Baraskar, A. Geiler, A. Yang, C. Pettiford, N. X. Sun, R. Goswami, M. A. Willard, C. Vittoria, V. G. Harris
Nian X. Sun
Nanocrystalline structured films of the alloy Ni₁₁Co₁₁Fe₆₆Zr₇B₄Cu₁ were deposited by pulsed laser ablation deposition onto fused quartz substrates. A substrate temperature of 300°C was found to produce films consisting of body-centered-cubic (bcc) metallic grains suspended in an amorphous matrix. The bcc grain size ranged from 5 - 8 nm for substrate temperatures up to 300°C. Measured values of coercivity were consistently below 4 Oe for films having a saturation magnetization, as 4π Ms, of ∽16 kG with in- plane uniaxial anisotropy fields of 25 to 30 Oe. The ferromagnetic resonance peak- to- peak derivative linewidth was measured to be 34 …
Voltage Impulse Induced Bistable Magnetization Switching In Multiferroic Heterostructures, T. X. Nan, Z. Y. Zhou, J. Lou, M. Liu, X. Yang, Y. Gao, S. Rand, N. X. Sun
Voltage Impulse Induced Bistable Magnetization Switching In Multiferroic Heterostructures, T. X. Nan, Z. Y. Zhou, J. Lou, M. Liu, X. Yang, Y. Gao, S. Rand, N. X. Sun
Nian X. Sun
We report on voltage impulse induced reversible bistable magnetization switching in FeGaB/lead zirconate titanate (PZT) multiferroic heterostructures at room temperature. This was realized through strain-mediated magnetoelectric coupling between ferroelectric PZT and ferromagnetic FeGaB layer. Two reversible and stable voltage-impulse induced mechanical strain states were obtained in the PZT by applying an electric field impulse with its amplitude smaller than the electric coercive field, which led to reversible voltage impulse induced bistable magnetization switching. These voltage impulse induced bistable magnetization switching in multiferroic heterostructures provides a promising approach to power efficient bistable magnetization switching that is crucial for information storage.
Equivalence Of Direct And Converse Magnetoelectric Coefficients In Strain-Coupled Two-Phase Systems, Jing Lou, Gerry N. Pellegrini, Ming Liu, Neil D. Mathur, Nian X. Sun
Equivalence Of Direct And Converse Magnetoelectric Coefficients In Strain-Coupled Two-Phase Systems, Jing Lou, Gerry N. Pellegrini, Ming Liu, Neil D. Mathur, Nian X. Sun
Nian X. Sun
We demonstrate an equivalence between direct and converse magnetoelectric effects in two-phase systems comprising piezoelectric and magnetostrictive materials. This was achieved by recasting the Maxwell relation in terms of the effective electrical and magnetic dipole moments for the system and comparing coupling strengths at the same electrical and magnetic d.c. biases. Our findings therefore apply to magnetoelectric systems comprising more than two phases and correct the two widely held but opposing views that are compromised by incorrect parameterization or inconsistent bias conditions.
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Nian X. Sun
This paper reports on the first demonstration of an ultra-miniaturized, high frequency (215 MHz) and high sensitivity MEMS resonant magnetic field sensor based on an AlN/FeGaB bilayer nano-plate resonator capable of detecting magnetic field at nano-Tesla level. Despite of the reduced volume and the high operating frequency of the sensor, high electromechanical performances were achieved (quality factor Q ≈ 511 and electromechanical coupling coefficient kt² ≈ 1.63%). This first prototype was characterized for different magnetic field levels from 0 to 152 Oe showing a frequency sensitivity of ~ 1 Hz/nT and a limit of detection of ~ 10 nT.
Epitaxial Growth Of M-Type Ba-Hexaferrite Films On Mgo (111) || Sic (0001) With Low Ferromagnetic Resonance Linewidths, Zhaohui Chen, Aria Fan Yang, Anton Geiler, Vincent Girard Harris (1962-), C. Vittoria, Paul R. Ohodnicki, K. Y. Goh, Michael E. Mchenry, Zhuhua Cai, Trevor L. Goodrich, Katherine S. Ziemer
Epitaxial Growth Of M-Type Ba-Hexaferrite Films On Mgo (111) || Sic (0001) With Low Ferromagnetic Resonance Linewidths, Zhaohui Chen, Aria Fan Yang, Anton Geiler, Vincent Girard Harris (1962-), C. Vittoria, Paul R. Ohodnicki, K. Y. Goh, Michael E. Mchenry, Zhuhua Cai, Trevor L. Goodrich, Katherine S. Ziemer
Anton Geiler
Barium hexaferrite (BaM) films were deposited on 10 nm MgO (111) films on 6H silicon carbide (0001) substrates by pulsed laser deposition from a homogeneous BaFe₁₂O₁₉ target. The MgO layer, deposited by molecular beam epitaxy, alleviated lattice mismatch and interdiffusion between film and substrate. X-ray diffraction showed strong crystallographic alignment while pole figures exhibited reflections consistent with epitaxial growth. After optimized annealing, these BaM films have a perpendicular magnetic anisotropy field of 16 900 Oe, a magnetization (as 4πs) of 4.4 kG, and a ferromagnetic resonance peak-to-peak derivative linewidth at 53 GHz of 96 Oe, thus demonstrating sufficient properties for …
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
Anton Geiler
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.
Tunable Fringe Magnetic Fields Induced By Converse Magnetoelectric Coupling In A Fega/Pmn-Pt Multiferroic Heterostructure, Trifon Fitchorov, Yajie Chen, Bolin Hu, Scott M. Gillette, Anton Geiler, Carmine Vittoria, Vincent G. Harris
Tunable Fringe Magnetic Fields Induced By Converse Magnetoelectric Coupling In A Fega/Pmn-Pt Multiferroic Heterostructure, Trifon Fitchorov, Yajie Chen, Bolin Hu, Scott M. Gillette, Anton Geiler, Carmine Vittoria, Vincent G. Harris
Anton Geiler
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.
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.
Direct Chemical Synthesis Of High Coercivity Air-Stable Smco Nanoblades, C. N. Chinnasamy, J. Y. Huang, L. H. Lewis, B. Latha, C. Vittoria, V. G. Harris
Direct Chemical Synthesis Of High Coercivity Air-Stable Smco Nanoblades, C. N. Chinnasamy, J. Y. Huang, L. H. Lewis, B. Latha, C. Vittoria, V. G. Harris
Laura H. Lewis
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 …