A5085817072- Magnetic properties of thin films
- Magnetic Properties and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Quantum and electron transport phenomena
- Theoretical and Computational Physics
- Force Microscopy Techniques and Applications
- Acoustic Wave Resonator Technologies
- Mechanical and Optical Resonators
- Physics of Superconductivity and Magnetism
- Magnetic Field Sensors Techniques
- Non-Destructive Testing Techniques
- Magneto-Optical Properties and Applications
- Microfluidic and Bio-sensing Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Adhesion, Friction, and Surface Interactions
- Advanced Memory and Neural Computing
- ZnO doping and properties
- Magnetic Properties and Synthesis of Ferrites
- Multiferroics and related materials
- Graphene research and applications
- Atomic and Subatomic Physics Research
- Advanced MEMS and NEMS Technologies
- Magnetic Properties of Alloys
- Metallic Glasses and Amorphous Alloys
- Neural Networks and Applications
Oregon State University
2015-2025
Conference Board
2013
Micro Magnetics (United States)
2013
Canadian Standards Association
2013
Institute of Electrical and Electronics Engineers
2013
Spintronics Research Network of Japan
2011
NVE Corporation (United States)
2003-2006
National Institute of Standards and Technology
2000-2003
Washington University in St. Louis
1995-2000
Hewlett-Packard (United States)
1996
Domain structures in CoFeB-MgO thin films with a perpendicular easy magnetization axis were observed by magneto-optic Kerr-effect microscopy at various temperatures. The domain wall surface energy was obtained analyzing the spatial period of stripe domains and fitting established models to period. In combination SQUID measurements anisotropy energy, this leads an estimate exchange stiffness width these films. These parameters are essential for determining whether walls will form patterned...
Low‐loss magnetization dynamics and strong magnetoelastic coupling are generally mutually exclusive properties due to opposing dependencies on spin–orbit interactions. So far, the lack of low‐damping, magnetostrictive ferrite films has hindered development power‐efficient magnetoelectric acoustic spintronic devices. Here, magnetically soft epitaxial spinel NiZnAl‐ferrite thin with an unusually low Gilbert damping parameter (<3 × 10 −3 ), as well evidenced by a giant strain‐induced...
New high-sensitivity solid-state magnetoresistive (MR) sensor technologies offer significant advantages in nondestructive evaluation (NDE) systems. A key advantage of MR sensors is a flat frequency response extending from dc to hundreds MHz, making them particularly attractive for low-frequency and multi-frequency eddy current detection deep-flaw depth profiling. are mass produced by thin film processing techniques similar integrated circuit manufacturing, dramatically reducing the cost per...
3-D printing processes, which use drop-on-demand inkjet printheads, have great potential in designing and prototyping magnetic materials. Unlike conventional deposition lithography, particles the ink can be aligned by an external field to achieve both high permeability low hysteresis losses, enabling development of novel composite materials components, e.g., for inductor antennae applications. In this work, we report technique with alignment capability. Magnetic films without particle are...
We report on the observation of reverse Doppler effect in backward spin waves reflected off surface acoustic waves. The are excited a yttrium iron garnet (YIG) film. Simultaneously, also generated. strain induced by magnetostrictive YIG film results periodic modulation magnetic anisotropy Thus, effect, travelling Bragg grating for is produced. reflecting this exhibit shift: shifting down rather than up frequency when an approaching wave. Similarly, shifted from receding
A new paradigm in energy-assisted magnetic recording, acoustically assisted recording (AAMR), is investigated. In this approach, a surface acoustic wave (SAW) applied to magnetostrictive medium temporarily lower its coercivity below the write field. Akin other technologies, AAMR provides strategy enable writing on high-coercivity media required for thermal stability high-density disk drives. Using contact tester, it demonstrated that current needed record data galfenol film reduced presence...
Most studies on iron oxide nanocrystals (NCs) suggest that the magnetic properties depend strongly size for diameters below 10 nm, but there is less agreement about how structure of NC surface influences properties. Because NCs hold promise applications from cancer detection and therapeutics to environmental remediation, it imperative understand those In most cases, effective significantly lower than measured physical size, a finding attributed spin canting or disorder at surface. A...
This letter describes the integration of giant magnetoresistance (GMR) sensors with a microfluidic system for velocity and size monitoring, enumeration flowing magnetic entities. We have fabricated microdevice that enables: (1) controlled formation picoliter-sized droplets ferrofluid separated by nonmagnetic oil; (2) continuous-flow sensing these droplets. It is shown flow velocity, droplet size, droplet-formation frequency can readily be determined from GMR response. These results are...
The performance of a surface acoustic wave (SAW) magnetic field sensor using galfenol (FeGa) thin film is investigated in this effort. We measure the change SAW velocity as function an externally applied for films varying thicknesses. A maximum 0.64%, greater than results reported similar sensors, obtained with 500 nm thick film.
The gamma and neutron radiation tolerance of magnetic tunnel junctions with MgO barriers were investigated. electrical transport properties measured in this effort. characterization results show no statistically significant change either tunneling magnetoresistance or coercivity from the radiation.
A theory of parametric interaction between spin waves localized in a waveguide and traveling elastic is developed for ferromagnetic thin films. The presented theoretical formalism takes into account an arbitrary spatial distribution the displacement field acoustic magnetization waves. Using theory, we examine forward-volume (FVSW) narrow Rayleigh surface substrate underneath waveguide. We show that, contrast to classical electromagnetic pumping, symmetry magnetoelastic allows generation...
This study investigates the parametric pumping of coherent forward volume spin waves using traveling surface acoustic in thin-film yttrium iron garnet. Theoretical analysis, micromagnetic modeling, and experimental validation nonlinear three-wave mixing interaction are presented. The energy momentum imparted by pump enable frequency translation angular deflection idler generated, providing a mechanism for spectral spatial separation signals magnonic devices. Experimental results demonstrate...
Three chopping techniques to address 1/f noise in spin-dependent tunneling magnetoresistive sensors are investigated. These include modulation of the sensitivity using orthogonal fields, modulation, and second-harmonic generation nonlinear response element flux concentrator permeability. Of these, only second technique resulted a slight reduction low-frequency noise. In order achieve significant by chopping, domain will have be reduced.
A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes alternating and 3 dot reversed are written using standing focusing waves, respectively. The pattern size-tunable, erasable, rewritable by changing the magnetic field power. This versatility, along its solid-state implementation (no moving parts) electronic control, renders it as promising for application recording,...
The linear and nonlinear interactions between spin waves (magnons) acoustic (phonons) in magnetostrictive materials provide an exciting opportunity for realizing novel microwave signal processing devices spintronic circuits. Here, we demonstrate the parametric pumping of by a ferrimagnet, possibility which has long been theoretically anticipated but never experimentally realized. Spin propagating thin film yttrium iron garnet-a ferrimagnet with low wave damping-are pumped using resonator...
Advances in magnetoresistive materials have recently enabled magnetic recording heads to achieve higher levels of performance. This article describes why signal outputs are necessary for improvements be made areal density. The requirements at an density 16 Mb/mm2 (10 Gb/in.2) discussed with regards both the channel and head design. Increased output from new multilayer is required counteract decrease due reduction size geometry. An shown feasible spin valve using magnetoresistance ratios 10%....
Spin waves are a promising prospect for the development of microwave information processing devices. A major obstacle in study spin is large intrinsic spin-wave damping most known magnetic materials. Viable amplification techniques thus required to make further progress spin-wave-based logic In this paper, we investigate novel technique parametric modulation using bulk acoustic waves. Although it not conclusive proof amplification, show that at twice frequency propagating on coupling into an...
Synthetic antiferromagnetic layers (SAF) are incorporated into spin transfer nanopillars giving a layer composition [Co(bottom)/Ru/Co(fixed)]/Cu/Co(free), where square brackets indicate the SAF. The Co(bottom) and Co(fixed) aligned antiparallel (AP) by strong indirect exchange coupling through Ru spacer. All three magnetic patterned, so this AP alignment reduces undesirable dipole fields on Co(free) layer. Adding Co(bottom)/Ru polarization of electron current passing nanopillar, leading to...
A simplified geometric model is presented for analyzing the thermal conduction problem in magnetoresistive heads. The leads to an approximate analytical solution resistance as a function of key and material parameters. reveals trends that will be helpful designing next generation high resolution recording
Ferromagnetic resonance (FMR) characterization, using a vector network analyzer (VNA), is widely used to determine anisotropy, g-factor, and Gilbert damping parameter of magnetic thin films, but results are typically reported without calculation the measurement accuracy. We present method processing VNA-FMR measurements both value confidence interval these properties. The discussion presented FMR data obtained from stacks MgO/CoFeB/Ta/CoFeB/MgO with varying CoFeB thickness. Measured...
The dependence of exchange stiffness and domain wall width on spacer layer material thickness in double-layer Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> Fe xmlns:xlink="http://www.w3.org/1999/xlink">60</sub> B films is investigated. are inferred from magneto-optic Kerr microscope images structure conjunction with ferromagnetic resonance spectroscopy vibrating sample magnetometer measurements anisotropy saturation magnetization....
We show that ferromagnetic resonance (FMR) selectively transfers angular momentum and energy from a microwave field to the lattice as measurable torque heat. The expected absorbed power are derived classically in terms of Landau–Lifshitz dynamics, including demagnetizing effects. is also described photon absorption process, which photons carry both momentum. FMR data shown for thin NiFe film deposited on micromechanical cantilever detector measures heat under nearly identical conditions.
Soft magnetic composites with aligned anisotropic particles can have properties not achievable in traditional single-phase materials. These materials are promising for high-frequency inductor and antenna applications. Composites uniaxial anisotropy, achieved by aligning rod-shaped a constant field, previously been reported. In this paper, we discuss the advantages conditions realizing planar disk-shaped rotating field. We use Ni-Fe microdisks UV-curable matrix as study system, present an...