A5089131841- Magnetic properties of thin films
- Multiferroics and related materials
- Antenna Design and Analysis
- Magnetic Properties and Applications
- Electromagnetic Effects on Materials
- Spine and Intervertebral Disc Pathology
- Innovative Energy Harvesting Technologies
- Energy Harvesting in Wireless Networks
- Advanced Antenna and Metasurface Technologies
- Characterization and Applications of Magnetic Nanoparticles
- Acoustic Wave Resonator Technologies
- Magnetic and transport properties of perovskites and related materials
- Medical Imaging and Analysis
- Electromagnetic Launch and Propulsion Technology
- Wireless Power Transfer Systems
- Magnetic Field Sensors Techniques
- Scoliosis diagnosis and treatment
- Brake Systems and Friction Analysis
- Advanced Mathematical Modeling in Engineering
- Muscle activation and electromyography studies
- Cervical and Thoracic Myelopathy
- Advanced Condensed Matter Physics
- Cellular and Composite Structures
- Micro and Nano Robotics
- Magneto-Optical Properties and Applications
Virginia Tech
2017-2022
University of California, Los Angeles
2015-2018
New York University Press
2018
MicroVision (United States)
2018
University of Kansas
2011-2015
This paper proposes the creation of strain powered antennas that radiate electromagnetic energy by mechanically vibrating a piezoelectric or piezomagnetic material. A closed form analytic model radiation from electrically small antenna is derived and analyzed. Fundamental scaling laws frequency dependence are discussed. The efficiency contrasted with conventional electric dipole. Analytical results show operating at first mechanical resonance produces most efficient relative to dipole...
A micromagnetic and elastodynamic finite element model is used to compare the 180° out-of-plane magnetic switching behavior of CoFeB Terfenol-D nanodots with perpendicular easy axes. The systems simulated here consist 50 nm diameter on top a 100 nm-thick PZT (Pby[ZrxTi1-x]O3) thin film, which attached Si substrate. This allows voltage pulses induce strain-mediated in field free environment. Coherent incoherent behaviors are observed both Terfenol nanodots, flipping associated larger or...
This paper experimentally demonstrates the operating principles of a near-field multiferroic antenna. The antenna uses piezoelectric lead-zirconate-titanate stack to apply time varying strain magnetoelastic iron gallium Fe80.77Ga19.23 (FeGa) rod. voltage induced controls net magnetization FeGa rod generate oscillating magnetic fields in free space surrounding Direct experimental measurements mechanical force, strain, field, and flux inside were collected show strong correlation with dynamic...
The recent push toward THz sensing, transduction, and memory has created a significant need for materials that operate above ferromagnetic resonance frequencies, which are typically in the low GHz range. Antiferromagnetic with resonances seem promising, but their lack of net magnetic moment makes manipulating them difficult. Here fully coupled magnetomechanical model is developed, showing antiferromagnetic single domains controllable via strain coupling. results indicate near-THz device...
Spin-orbit torque (SOT) allows energy-efficient control of magnetism for nonvolatile digital memory. However, deterministic perpendicular switching requires lateral symmetry breaking, and remains a challenge in SOT devices. Here mechanism is simulated, showing that uniaxial anisotropies like strain-induced magnetoelastic anisotropy can break system's yield field-free This method electric field may inspire next-generation memory devices such as magnetic random-access (MRAM).
This paper presents the measurement of strain-mediated multiferroic control spontaneous exchange bias (SEB) in magnetostrictive nickel/nickel oxide (Ni/NiO) bilayers on ferroelectric lead magnesium niobate-lead titanate (PMN-PT). Electric field a positive to negative shift was measured, with an overall 40.5 Oe, corresponding 325% change. Observed changes coercivity are also reported and provide insight into role competing anisotropies these structures. The findings this evidence that...
This paper presents the experimental measurements of a highly magnetoelastic material (Galfenol) under impact loading. A Split-Hopkinson Pressure Bar was used to generate compressive stress up 275 MPa at strain rates either 20/s or 33/s while measuring stress-strain response and change in magnetic flux density due coupling. The average Young's modulus (44.85 GPa) invariant rate, with instantaneous stiffness ranging from 25 55 GPa. lumped parameters model simulated measured pickup coil...
Abstract Spinal fusion surgeries have a high failure rate for difficult‐to‐fuse patients. A piezoelectric spinal implant was developed to overcome the issues with other adjunct therapies. Stacked generators were used improve power generation at low electrical load resistances. The effects of number layers on average maximum and optimal resistance characterized. mechanical preload, frequency, amplitude also Increasing from one nine found lower 1.00 GΩ 16.78 MΩ while maintaining generation....
Precise control and manipulation of nano-beads have various applications, e.g. cell sorter, 3D printing nano-motors. In this paper we present an approach in which use voltage on a piezolecetric substrate order to reorient the magnetization nano-disk. turn drives dynamic nano-beads. This is energy efficient method motion since only applied substrate. The mechanism consists Ni disk three pairs surface electrodes placed PZT By controlling different electrodes, will rotate with constant angular...
Abstract Failure rates of spinal fusion are high in smokers and diabetics. The authors investigating the development a piezoelectric composite biomaterial interbody device design that could generate clinically relevant levels electrical stimulation to help improve rate for these patients. A lumped parameter model implant was developed based on has been utilized successfully predict power generation piezoceramics. Seven variables (fiber material, matrix fiber volume fraction, aspect ratio,...
Previous studies examining the response of magnetoelastic materials to shock waves have predominantly focused on applications involving pulsed power generation, with limited attention given actual wave propagation characteristics. This study provides detailed magnetic and mechanical measurements dispersion. Laser generated rarefacted exceeding 3 GPa rise times 10 ns were introduced samples material Galfenol. The resulting reveal evolution into a compressive acoustic front lateral release...
This paper describes a method for achieving continuous deterministic 360$^{\circ} $ magnetic moment rotations in single domain magnetoelastic discs, and examines the performance bounds mechanically lossless multiferroic bead-on-a-disc motor based on dipole coupling these discs to small nanobeads. The are attained by controlling relative orientation of four-fold anisotropy (e.g., cubic magnetocrystalline anisotropy) with respect two-fold anisotropy. approach produces from quasi-static regime...
A manufacturing method was developed to create a piezoelectric 3-layer stacked, macro fiber composite generator operating in d33 mode promote bone growth spinal fusion surgeries. specimen of 9 × 17 mm thick constructed from 800 μm diameter PZT fibers and medical grade epoxy. Electromechanical testing performed at three stages determine the influence these processes on power generation. An average peak over 335 μW generated heat-treated during simulated human body loads. The work provides...
Strain mediated Bennett clocking has only recently been experimentally demonstrated and suffered from high error rates. Most models used to explain this behavior are macrospin models. Predictions of these do not match experimental designs since they consider all spins rotating coherently no magnetoelastic strain feedback. In paper a fully coupled nonlinear model (LLG plus elastodynamics) was simulate voltage induced clocking. This modelling captures the full spin dynamics as well shape...
Abstract This paper presents an analytic model of one dimensional magnetostriction. We show how specific assumptions regarding the symmetry key micromagnetic energies (magnetocrystalline, magnetoelastic, and Zeeman) reduce a general three-dimensional statistical mechanics to one-dimensional form with exact solution. additionally provide useful equations help ensure numerical accuracy. Numerical results that maintains accuracy over large range applied magnetic fields stress conditions...
Electric antennas are still large structures (approximately 1m for 300 MHz operation), and have so far eluded the miniaturization trend common in electronics industry. This is due part to an impedance mismatch with free space, increase system losses from ohmic heating as antenna dimensions shrink. Recent work has proposed using multiferroic heterostructures create small energy efficient antennas. idea was first explored by Rowen's 1961 paper on electromagnetic (EM) radiation YIG, Mindlin's...
Hypervelocity impacts generate shockwaves causing catastrophic damage and failure of surrounding material structures. Adaptive materials have been previously studied to mitigate by providing diagnostics tools, wave steering, dissipating mechanical energy. Numerous ferroelectric studies conducted, with less focus on ferromagnets, or magnetoelasticity. This presentation explores the response magnetoelastic Galfenol (Fe81.6Ga18.4) high strain-rate, stress amplitude loading. Experimentally, 2...
As traditional electric motors scale down, the available power density rapidly decreases. For a motor occupying volume of 1 micron cubed, is roughly six orders magnitude lower than millimeter cubed motor. Strain-mediated multiferroic heterostructures have recently been proposed to create high density, scale, magnetic motors. These leverage magnetoelastic anisotropy rotate moment small disk, and use dipolar forces couple rotors or beads stray field. A key challenge creation these...