jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

1 Apr 2009

Volume 105, Issue 7, Articles (07xxxx)

Page 2 of 26 Pages Return to All Sections Previous Page Next Page
back to top
RSS Feeds
back to top Soft Magnetic Materials and Domains

Outer shell structure in nearly zero magnetostrictive amorphous microwires

T.-A. Óvári, H. Chiriac, and Mihaela Lostun

J. Appl. Phys. 105, 07A325 (2009); http://dx.doi.org/10.1063/1.3072826 (3 pages) | Cited 2 times

Online Publication Date: 11 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nearly zero magnetostrictive microwires have been proven to be very versatile, due to their extremely soft magnetic properties, the changes in their magnetization mechanism with dimensions, and the appearance of sensitive application-related effects, such as the large Barkhausen and the giant magnetoimpedance effects. Their sensitive magnetoimpedance response originates in the specific domain structure, composed of an inner core and an outer shell (OS), since the OS with a circumferential easy axis is the main region involved in the magnetoimpedance effect. The circumferential OS is believed to display a bamboolike structure with consecutive rings circumferentially magnetized in opposite directions. However, earlier theoretical studies predicted a uniformly magnetized OS as being energetically favored. This paper aims to clarify this contradiction. The variation of the magnetostatic energy from the bamboo domain to the uniformly magnetized state has been calculated and it has been found to be null. Therefore, a uniformly magnetized OS has lower energy due to the absence of domain walls. Calculation results are supported by magneto-optical Kerr effect surface domain images and surface hysteresis loops. For large values of the metallic nucleus diameter, as well as for microwires with the glass coating removed, the OS vanishes, being replaced with a surface region with helical magnetization, which expands toward the microwire surface.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Ch Domain walls and domain structure
78.20.Ls Magneto-optical effects
75.50.Kj Amorphous and quasicrystalline magnetic materials

Cluster spin-glass state and Kondo behavior in Sm-based bulk metallic glasses

C. L. Lu, S. Dong, K. F. Wang, J.-M. Liu, Q. Wang, and C. Dong

J. Appl. Phys. 105, 07A326 (2009); http://dx.doi.org/10.1063/1.3073829 (3 pages)

Online Publication Date: 13 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the magnetization and electrical transport properties of Sm-based ternary magnetic bulk metallic glasses at low temperatures. A cluster spin-glass phase is evidenced below Tf ∼ 25 K, which is probably ascribed to competition among the multifold magnetic interactions and intrinsic structural inhomogeneity, and further demonstrated by the magnetic hysteresis under field-cooling conditions. It is shown that the short-range magnetic clusters play as scattering centers for conductive electrons and result in a Kondo-like transport behavior in highly spin disordered Sm50Al25Co25 at low temperature.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
75.50.Lk Spin glasses and other random magnets
75.50.Kj Amorphous and quasicrystalline magnetic materials

Experimental verification and analytical approach to influence stator skew on electromagnetic performance of permanent magnet generators with multipole rotor

Jang-Young Choi, Seok-Myeong Jang, and Kyoung-Jin Ko

J. Appl. Phys. 105, 07A327 (2009); http://dx.doi.org/10.1063/1.3075559 (3 pages)

Online Publication Date: 19 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper deals with experimental verification and analytical approach to influence stator skew on electromagnetic performance of a permanent magnet generator (PMG) with multipole rotor. The analytical expressions for magnetic field distributions are due to permanent magnets and the two-dimensional permeance function considering skew effects are established. On the basis of these analytical solutions, the analytical solutions for cogging torque and back-emf considering skew effects are also derived. Then, by applying estimated electrical parameters to a simple equivalent circuit of one phase for the PMG, output performances of the PMG with/without a skewed stator are investigated. Finally, by confirming that all analytical results are validated extensively by nonlinear finite element calculations and measurements, the validity of analysis methods presented in this paper is verified, and the influence stator skew on cogging torque, back-emf, and output performances of the PMG is also clearly described.
Show PACS
84.50.+d Electric motors
02.70.Dh Finite-element and Galerkin methods

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications

K. N. Collier, N. J. Jones, K. J. Miller, Y. L. Qin, D. E. Laughlin, and M. E. McHenry

J. Appl. Phys. 105, 07A328 (2009); http://dx.doi.org/10.1063/1.3054376 (3 pages) | Cited 8 times

Online Publication Date: 19 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the oxidation products and qualitative rates for polydisperse FeCo magnetic nanoparticles (MNPs) synthesized using an induction plasma torch. X-ray diffraction (XRD) and TEM showed MNPs to have a thin ferrite shell. Nanopowders were isochronally annealed to promote oxidation and XRD was used to follow the evolution of the FeCo core and the Fe3O4 and FeO oxide shells. Isothermal anneals were used to follow oxidation kinetics at 350 and 500 °C. High resolution transmission electron microscopy (HRTEM) revealed faceted morphologies terminated at (100) and (110) FeCo faces with (110)FeCo∥(111)oxide and (100)FeCo∥(100)oxide, and [010]FeCo∥[011]oxide orientation relationships between the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples of aqueous ferrofluids similarly loaded with as synthesized and oxidized MNPs.
Show PACS
87.50.st Therapeutic applications

Incorporating core hysteresis properties in three-dimensional computations of transformer inrush current forces

A. A. Adly and H. H. Hanafy

J. Appl. Phys. 105, 07A329 (2009); http://dx.doi.org/10.1063/1.3072768 (3 pages) | Cited 1 time

Online Publication Date: 23 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is well known that transformer inrush currents depend upon the core properties, residual flux, switching instant, and the overall circuit parameters. Large transient inrush currents introduce abnormal electromagnetic forces which may destroy the transformer windings. This paper presents an approach through which core hysteresis may be incorporated in three-dimensional computations of transformer inrush current forces. Details of the approach, measurements, and simulations for a shell-type transformer are given in the paper.
Show PACS
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
85.70.-w Magnetic devices

Isothermal oxidation behaviors of FeCoV and FeCoVNb alloys

Zafer Turgut, John C. Horwath, Meiqing Huang, and Jack E. Coate

J. Appl. Phys. 105, 07A330 (2009); http://dx.doi.org/10.1063/1.3078412 (3 pages) | Cited 2 times

Online Publication Date: 26 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The present study investigates the isothermal oxidation of two iron-cobalt based alloys at 500 °C for up to 5000 h. Both alloys exhibit crack-free oxide layers consist of a porosity-free iron rich outer layer and a solute rich inner layer populated with islands of solute oxides and porosities. X-ray diffraction measurements reveal the presence of MO–Fe2O3-type (where M = Co, Nb, and/or V) spinel structures along with Fe2O3. Analysis shows that the oxidation follows the parabolic rate law for both alloys with niobium containing alloy exhibiting a higher oxidation rate. Comparison of yield strengths (σ0) of oxidized specimens to those aged similarly under an inert atmosphere indicates that two competing mechanisms occur. Surface oxidation decreases the yield strength while precipitation reactions inside the iron-cobalt matrix increase the yield strength of the matrix.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.65.Mq Oxidation
81.40.Lm Deformation, plasticity, and creep
62.20.fg Shape-memory effect; yield stress; superelasticity
81.30.Mh Solid-phase precipitation
64.75.-g Phase equilibria

Magnetic properties of Fe-based ribbons with controlled permeability prepared by continuous pulse annealing under tensile stress

Kotaro Takagi, Takeshi Yanai, Ken-ichiro Takahashi, Masaki Nakano, Hirotoshi Fukunaga, and Yoshihito Yoshizawa

J. Appl. Phys. 105, 07A331 (2009); http://dx.doi.org/10.1063/1.3068032 (3 pages) | Cited 1 time

Online Publication Date: 30 March 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An amorphous Fe73.5Cu1Nb3Si15.5B7 ribbon was pulse annealed continuously under tensile stress by being passed through in an infrared furnace switched on and off repeatedly for preparation of a nanocrystallized toroidal core with controlled permeability. Optimization of the duty ratio D( = Ton/T) of the furnace enabled us to obtain ribbons with low Hc(<10 A/m) and completely developed anisotropy under a high moving velocity of the ribbon, 50 cm/min. ac magnetic properties of a toroidal core, which is made from the pulse-annealed ribbon, at Bm = 0.1 T were measured in the frequency range of 0.1–1 MHz. The loss of the prepared core at f = 0.1 MHz is 0.50 J/m3, which is lower than those for a gapped ferrite, sendust powder, and amorphous powder core. The relative permeability of approximately 330 was constant up to 1 MHz. These results suggest that the continuous stress annealing by pulse annealing method is one of the hopeful methods for preparation of a long ribbon with excellent magnetic properties.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
81.16.-c Methods of micro- and nanofabrication and processing
75.50.Tt Fine-particle systems; nanocrystalline materials
81.07.Bc Nanocrystalline materials
75.50.Kj Amorphous and quasicrystalline magnetic materials

Synthesis and characterization of metastable nanocrystalline cobalt

C. Osorio-Cantillo and O. Perales-Perez

J. Appl. Phys. 105, 07A332 (2009); http://dx.doi.org/10.1063/1.3072091 (3 pages) | Cited 2 times

Online Publication Date: 3 April 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Applications of elemental cobalt are consequence of its phase-dependent magnetic properties; the anisotropic high-coercivity hcp-Co phase is preferred for permanent magnet applications, while the more symmetric low coercivity fcc- and pseudocubic ε-Co can be used in soft magnetic applications involving power electronics and magnetic write heads. The present work addresses the synthesis and characterization of nanocrystalline cobalt particles produced through a modified polyol-based approach conducive to the formation of fcc-, hcp-, or ε-Co phases. Metastable ε-Co and hcp-Co were exclusively formed in the presence of trimethylene glycol. In turn, fcc-Co or mixture of fcc/hcp-Co phases were produced in tetraethylene glycol. The average crystallite size in all cases ranged between 10 and 13 nm. Magnetic measurements confirmed the strong influence of synthesis conditions on crystal structure and hence on magnetic properties of nanocrystalline cobalt. The coercivity of the products varied from 338 to 550 Oe depending on the presence of the different cobalt structures.
Show PACS
81.16.Be Chemical synthesis methods
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Cc Other ferromagnetic metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

The change in permeability spectra due to ion irradiation in the Co-based amorphous ribbon

D. G. Park, C. Y. Park, H. Song, C. G. Kim, and Y. M. Cheong

J. Appl. Phys. 105, 07A333 (2009); http://dx.doi.org/10.1063/1.3086714 (3 pages)

Online Publication Date: 7 April 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Ar ion has been irradiated by an ion implanter with energy of 50, 70, and 100 keV and an ion dosage was set to 1.0×1017 ion/cm2 at a beam flux of 3.7 μA/cm2. The ion irradiation decreased the initial permeability and increased the relaxation frequency, and the behavior of permeability spectra due to ion irradiation was explained with damped harmonic model of domain wall on the general basis of magnetization mechanism. The ion irradiation gives rise to a significant change on the restoring force of domain wall but minor effect on the spin rotation. The enhancement in the permeability of the amorphous ribbon upon ion irradiation leads to a parallel improvement of giant magneto impedance response of the material, which is of practical use for sensing applications.
Show PACS
61.80.Jh Ion radiation effects
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.47.De Giant magnetoresistance
75.30.Ds Spin waves

Performance prediction of a small-sized herringbone-grooved bearing with ferrofluid lubrication considering cavitation

Yung-Yuan Kao, Paul C.-P. Chao, Zong-Bin Liu, Zhi-Kuan Wang, Po-Wen Liu, Jeng-Shen Huang, and Chang-Chun Chang

J. Appl. Phys. 105, 07A334 (2009); http://dx.doi.org/10.1063/1.3072771 (3 pages)

Online Publication Date: 9 April 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The small-sized herringbone groove journal bearing (HGJB), i.e., so-called “magnetic bearing,” filled with Newtonian ferrofluid lubrication is investigated via finite difference analysis (FDA), with consideration of cavitation zones in HGJB. The FDA starts with constructing the mass flux equations of the HGJB filled with ferrofluid. Discretization for FDA is next performed over the bearing clearance domain, from which algebraic finite difference equations based on the mass flow balance over the clearance domain are derived. Solving the equations, rotordynamic coefficients, cavitation zones, and side leakage rate are successfully predicted to show effectiveness in enhancing bearing performance by ferrofluid.
Show PACS
85.70.-w Magnetic devices
47.65.Cb Magnetic fluids and ferrofluids
02.70.Bf Finite-difference methods

Calculation of eddy-current loss in multilayer magnetic films considering displacement current

Di Yao and Charles R. Sullivan

J. Appl. Phys. 105, 07A335 (2009); http://dx.doi.org/10.1063/1.3074134 (3 pages)

Online Publication Date: 9 April 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
At high frequency, displacement current in dielectric layers of multilayer magnetic thin films becomes significant, and eddy-current loss can be much worse than would be predicted without considering displacement current. Two-dimensional finite-element method simulations were used to study the behavior of eddy-current loss in multilayer thin films from 1 kHz to 1 GHz. A closed-form expression for accurate loss prediction with error less than 10% was developed, and its consistency with experimental measurements on Co–Zr–O/ZrO2 multilayer films was checked.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.-d Domain effects, magnetization curves, and hysteresis
68.55.aj Insulators
77.55.-g Dielectric thin films

Coil geometry for efficient active compensation with separated magnetic shields

Yoshihiro Nakashima and Ichiro Sasada

J. Appl. Phys. 105, 07A336 (2009); http://dx.doi.org/10.1063/1.3086291 (3 pages) | Cited 1 time

Online Publication Date: 10 April 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have already proposed a new method of magnetic shielding aiming for magnetocardiography, in which magnetic shells are separated and a new compensation scheme is employed to allow for wide space between them. Each magnetic shell that consists of a half of the cylinder (diameter = 20 cm and length = 60 cm) and two flanges at both ends of the half cylinder extending along the radial direction has a saddle coil on its outer surface with the coil’s long straight section running parallel to the axis of the cylinder. In this paper, the relationship between the width of the long straight sections of the saddle coil and the efficiency of the active compensation is investigated by the finite element method (FEM) analysis and by experiments. A magnetic shield used in this study is a double shell structure where each shell is made of stacked amorphous tapes and the outer shell has a magnetic shaking coil for the enhancement of the permeability. We have found that for a given magnetic field, the compensation current necessary for a given magnetic field varies by a factor of 3 depending on the width of a saddle coil and that its value monotonically decreases with increasing the width. We have also confirmed that the phase delay of the compensation magnetic field experienced while it comes in the magnetic shell is small.
Show PACS
87.50.C- Static and low-frequency electric and magnetic fields effects
87.10.Kn Finite element calculations
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
back to top Ferrites, Garnets, and Microwave Materials

Tuning magnetic properties of yttrium iron garnet film with oxygen partial pressure in sputtering and annealing process

Qing-Hui Yang, Huai-Wu Zhang, Qi-Ye Wen, Ying-Li Liu, and John Q. Xiao

J. Appl. Phys. 105, 07A501 (2009); http://dx.doi.org/10.1063/1.3055286 (3 pages) | Cited 2 times

Online Publication Date: 30 January 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, the magnetic properties of these films which deposited and annealed at different atmospheres were investigated. The experimental results show that the magnetic properties of yttrium iron garnet films prepared by rf magnetron sputtering method can be tuned with oxygen partial pressure in sputtering and annealing processes. The optimal condition is depositing in atmosphere of R = 0 and annealing at 0.5 Pa O2, or depositing in atmosphere of R = 2% and annealed in vacuum.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.15.Cd Deposition by sputtering
75.50.Gg Ferrimagnetics
68.55.aj Insulators
81.40.Gh Other heat and thermomechanical treatments

Spinwave propagation in lossless cylindrical magnonic waveguides

Haiwen Xi, Xiaobin Wang, Yuankai Zheng, and Pat J. Ryan

J. Appl. Phys. 105, 07A502 (2009); http://dx.doi.org/10.1063/1.3056142 (3 pages) | Cited 5 times

Online Publication Date: 2 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spinwave propagation in clad cylindrical magnonic waveguides is investigated under linear approximation. With the assumption of no magnetic damping, characteristic equation to determine the bound spinwave modes has been obtained based on the structural and magnetic properties of the waveguides. The study is then applied to homogenous magnetic nanowires with no cladding. Spinwave characteristics and properties, such as the dispersion relationship and group velocity, can be described analytically.
Show PACS
75.30.Ds Spin waves
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Tt Fine-particle systems; nanocrystalline materials

Ferromagnetic resonance and dielectric and magnetic properties of pure and diluted ferrites in millimeter waves

Mohammed N. Afsar, Shu Chen, and Konstantin A. Korolev

J. Appl. Phys. 105, 07A503 (2009); http://dx.doi.org/10.1063/1.3059611 (3 pages) | Cited 3 times

Online Publication Date: 4 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transmittance measurements on pure and diluted barium ferrites, nickel zinc manganese ferrites, and nickel cobalt copper ferrites in millimeter wave-frequency range from 30 to 120 GHz have been performed for the first time. A free space millimeter wave magneto-optical approach has been successfully employed for the dielectric and magnetic characterization of ferrite materials. Simultaneous determination of dielectric permittivity and magnetic permeability has been carried out from a single set of transmittance measurements. Frequency dependences of the magnetic permeability and dielectric permittivity on pure and diluted ferrites in millimeter waves have been obtained.
Show PACS
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.50.Gg Ferrimagnetics
77.22.Ch Permittivity (dielectric function)
78.20.Ls Magneto-optical effects
84.40.-x Radiowave and microwave (including millimeter wave) technology
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Domain-acoustic echo phenomenon in europium garnet and iron borate

G. I. Mamniashvili, Y. G. Sharimanov, A. M. Pohorily, and O. M. Kuzmak

J. Appl. Phys. 105, 07A504 (2009); http://dx.doi.org/10.1063/1.3058672 (2 pages)

Online Publication Date: 5 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The results of a comparative study of domain-acoustic echo (DAE) signals in polycrystalline ferrite Co0.01Mn0.05Cu0.18Ni0.2Mg0.72Fe0.6O4, europium garnet, and iron borate are presented. The DAE signals were observed at 20 MHz. They possess a long time memory and are related with displacements of domain walls. In particular, DAE in the europium garnet is characterized by particularly intensive signals and has the lowest threshold for exciting radio-frequency pulse powers and suppressing magnetic field values.
Show PACS
75.50.Gg Ferrimagnetics
62.65.+k Acoustical properties of solids
75.60.Ch Domain walls and domain structure

Microwave-induced combustion synthesis of Li0.5Fe2.5−xMgxO4 powder and their characterization

Y. P. Fu and C. H. Lin

J. Appl. Phys. 105, 07A505 (2009); http://dx.doi.org/10.1063/1.3061931 (3 pages) | Cited 2 times

Online Publication Date: 5 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Li0.5Fe2.5−xMgxO4 (0≦x≦1.0) powders with small and uniformly sized particles were successfully synthesized by microwave-induced combustion using lithium nitrate, ferric nitrate, magnesium nitrate, and carbohydrazide as the starting materials. This process takes only a few minutes to obtain as-received Mg-substituted lithium ferrite powders. The results revealed that the lattice constant increases nonlinearly with increasing Mg content in the Li0.5Fe2.5−xMgxO4 specimens. Moreover, the magnetic properties of Mg-substituted lithium ferrite were also strongly affected by Mg concentration. The saturation magnetization (Ms) of 71.1 emu/g was found at Li0.5Fe2.5O4 specimen. As increased Mg content, the saturation magnetization (Ms) and remanent magnetization (Mr) decreased significantly. This is ascribed to the fact that as Mg content increases, A-O-B (where A represents tetrahedral sites and B represents octahedral sites in ferrite of the spinel type) interactions become weak, and consequently B-O-B interaction becomes stronger. Transmission electron microscopy (TEM) micrograph revealed that Mg-substituted lithium ferrite powders are distributed in the range from 50 to 80 nm with well-defined crystallinity.
Show PACS
81.05.Cy Elemental semiconductors
61.66.Fn Inorganic compounds
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Gg Ferrimagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

The effect of proton irradiation on magnetic properties of lithium ferrites

Sung Wook Hyun, Taejoon Kouh, Sam Jin Kim, and Chul Sung Kim

J. Appl. Phys. 105, 07A506 (2009); http://dx.doi.org/10.1063/1.3070611 (3 pages) | Cited 4 times

Online Publication Date: 6 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of proton irradiation on magnetic properties of lithium ferrites has been investigated with x-ray diffraction (XRD), magnetization, and Mössbauer spectroscopy measurements. Li0.5Fe2.5O4 powders have been fabricated by the sol-gel method. Following the annealing at 700 °C, these samples have been proton irradiated with 1, 5, and 10 pC/μm2. The analysis of XRD patterns by Rietveld refinement method shows that these samples have ordered cubic spinel structures with space group of P4332. We have observed that the corresponding lattice constant a0 linearly increases from 8.3301 to 8.3314±0.0001 Å with increasing proton irradiation. Compared to nonirradiated sample, which has the saturation magnetization (Ms) of 66.4 emu/g and oxygen occupancy of 3.9980 at room temperature, the values of magnetization and oxygen occupancy at room temperature are 66.0, 62.6, and 60.8 emu/g and 3.9840, 3.9452, and 3.9272, respectively, for 1, 5, and 10 pC/μm2 irradiated powders. Also, the coercivity (Hc) decreases from 175.6 to 154.0 Oe with increasing proton irradiation. The Mössbauer spectra taken at room temperature show that the values of isomer shift (δ) for the tetrahedral (A) and octahedral (B) sites are consistent with the Fe3+ valence state. The results suggest that the proton irradiation induces the oxygen vacancy defects, which in turn leads to the changes in magnetic properties.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
76.80.+y Mössbauer effect; other γ-ray spectroscopy
75.50.Gg Ferrimagnetics
61.80.Jh Ion radiation effects
81.40.Gh Other heat and thermomechanical treatments
61.72.jd Vacancies

Effect of CeO2 buffer layer on the microstructure and magnetic properties of yttrium iron garnet film on Si substrate

Qing-Hui Yang, Huai-Wu Zhang, Qi-Ye Wen, Ying-Li Liu, and John Q. Xiao

J. Appl. Phys. 105, 07A507 (2009); http://dx.doi.org/10.1063/1.3056404 (3 pages) | Cited 2 times

Online Publication Date: 9 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Yttrium iron garnet films were grown by radio frequency magnetron sputtering on Si(111) substrate with and without CeO2 buffer layer, and influence of CeO2 buffer on the microstructure and magnetic behaviors of the films were investigated. As compared with the film without buffer, a larger saturation magnetizaton (Ms), lower coercive force (Hc), and higher remnant magnetization (Mr) were obtained due to the introduction of CeO2 layer. The higher Ms results from the denser structure and the smaller content of Fe2+ ions. The lower Hc and higher Mr can be explained by the small surface roughness and crystal grains size. The film on CeO2 buffer layer possess fine microstructure and its surface roughness is smaller than the unbuffered films, which provides an increased exchange between the crystal grains and an enhanced spontaneous magnetization effect, leading to the higher remnant magnetization.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
81.15.Cd Deposition by sputtering
68.35.B- Structure of clean surfaces (and surface reconstruction)
75.30.Cr Saturation moments and magnetic susceptibilities
68.55.A- Nucleation and growth

Numerical analysis on power loss mechanism of Fe55Al18O27 thin films for conduction noise through microstrip line

Gi-Bong Ryu and Sung-Soo Kim

J. Appl. Phys. 105, 07A508 (2009); http://dx.doi.org/10.1063/1.3068014 (3 pages) | Cited 3 times

Online Publication Date: 13 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
With a simulation model of microstrip line attached by Fe55Al18O27 thin film of high magnetic loss, S parameters and power absorption has been analyzed by finite element method in the frequency range of available material parameters (0.1–1.5 GHz). It is demonstrated that the S parameters and power absorption are dominantly controlled by the electrical properties of the thin film. Although the film has a large value of magnetic loss resulting from ferromagnetic resonance, it is predicted that the power dissipation by magnetic loss is negligibly small. Simulation under assumption of high electrical resistivity shows that both S11 and S21 values approach to the value of original microstrip line. Another simulation of sheet resistance effect by film thickness control shows that higher value of power absorption is predicted in the films of small thickness mainly due to lower reflection loss. For the conductive and magnetic Fe55Al18O27 thin film, it is concluded that the dominant power loss mechanism is eddy current loss for magnetic field or Ohmic loss for electric field around the strip conductor in the frequency range investigated.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.55.jd Thickness
73.61.Ng Insulators

Bounds on the dynamic magnetic properties of multiresonant nanostructure composites in exchange resonance model

P. H. Zhou and L. J. Deng

J. Appl. Phys. 105, 07A509 (2009); http://dx.doi.org/10.1063/1.3072074 (3 pages) | Cited 2 times

Online Publication Date: 13 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Existing bounds expression established on the sum of the gyromagnetic losses is limited by static magnetic interactions. In this paper, we deduce a bounds relation from the Bloch–Bloembergen theorem to depict both the uniform resonance and exchange resonance. It is shown to agree with experiments, of particular relevance to the competition between static magnetic force and exchange interaction. An analytic explanation on favorable multiresonance phenomenon in nanocrystalline iron flakes is achieved.
Show PACS
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Bb Fe and its alloys
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Microwave tunability in a GaAs-based multiferroic heterostructure: Co2MnAl/GaAs/PMN-PT

Y. Chen, J. Gao, J. Lou, M. Liu, S. D. Yoon, A. L. Geiler, M. Nedoroscik, D. Heiman, N. X. Sun, C. Vittoria, and V. G. Harris

J. Appl. Phys. 105, 07A510 (2009); http://dx.doi.org/10.1063/1.3068543 (3 pages) | Cited 7 times

Online Publication Date: 17 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
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 ∼ 125 MHz at X-band. It yields a large ME coupling (7 Oe cm/kV) and microwave tunability ( ∼ 32 MHz/kV cm−1), compared to other trilayer multiferroic composite structures. In addition, static magnetization measurement indicates a reduction in the remanence magnetization while applying the electric field, which corroborates the ME interactions mediated by the translation of magnetoelastic forces in this structure. This work explores the potential of multiferroic heterostrucuture transducers for use in FMR microwave devices tuned by electric fields.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
77.80.-e Ferroelectricity and antiferroelectricity
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
77.65.-j Piezoelectricity and electromechanical effects
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
07.07.Mp Transducers

Growth and characterization of 144 μm thick barium ferrite single crystalline film for microwave device application

Jeevan Jalli, Yang-Ki Hong, Seok Bae, Jae-Jin Lee, Gavin S. Abo, Andrew Lyle, Sung-Hoon Gee, Hwachol Lee, Tim Mewes, Jeong-Chul Sur, and Sung-Ik Lee

J. Appl. Phys. 105, 07A511 (2009); http://dx.doi.org/10.1063/1.3062824 (3 pages) | Cited 5 times

Online Publication Date: 18 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Liquid phase epitaxy technique was used to grow 144 μm thick barium ferrite (BaFe12O19; BaM) single crystalline films on (111) Gd3Ga5O12 substrate. The growth rate of 72 μm/h was achieved with a flux system of Fe2O3–BaCO3–Na2CO3. The grown BaM films show single crystalline (000l) orientation that was confirmed by x-ray diffraction and magnetic torque curves. The saturation magnetization (4πMs) and the anisotropy field (Hk) were found to be 4.2 kG and 16.0 kOe, respectively. The ferrimagnetic resonance linewidth (ΔH) at 35 GHz was measured to be 0.1 kOe.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
68.55.J- Morphology of films
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.30.Gw Magnetic anisotropy
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
68.55.at Other materials

Magnetic and optical properties of rf-sputtered zinc ferrite thin films

M. Sultan and R. Singh

J. Appl. Phys. 105, 07A512 (2009); http://dx.doi.org/10.1063/1.3072381 (3 pages) | Cited 9 times

Online Publication Date: 19 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Zn-ferrite (ZnFe2O4) thin films were deposited by rf-magnetron sputtering on glass substrates at room temperature (RT) in pure oxygen environment. The as-deposited films were investigated by x-ray diffraction to show that single phase nanocrystalline spinel patterns belong to zinc ferrite. The magnetization shows ferrimagnetic behavior, and it strongly depends on oxygen working pressure. The maximum magnetization of 230 emu/cm3 (42 emu/g) at RT is obtained for the film deposited at 27 mTorr of oxygen pressure. The oxygen vacancy concentration and random distribution of Zn2+ and Fe3+ on both tetrahedral and octahedral sites are the possible reasons of high magnetization due to rapid cooling of sputtered vapors to form solid state film. The optical properties of the films show 85% transparency above 550 nm wavelength. The estimated values of direct and indirect band gaps are 2.5 and 1.9 eV, respectively.
Show PACS
75.50.Gg Ferrimagnetics
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Tt Fine-particle systems; nanocrystalline materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.66.Nk Insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Experimental results and model for the permeability of sprayed NiZn ferrite films

O. Acher, M. Ledieu, M. Abe, M. Tada, and T. Nakagawa

J. Appl. Phys. 105, 07A513 (2009); http://dx.doi.org/10.1063/1.3055352 (3 pages) | Cited 4 times

Online Publication Date: 23 February 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The high-frequency permeabilities of several NiZn ferrite films prepared by spray plating were investigated up to 6 GHz. An adaptation of the Bouchaud–Zérah effective medium model provided an analytical expression for the microwave permeability, with a simple dependence on the magnetization distribution. An excellent agreement with the experimental results was obtained, in the demagnetized state as well as in the remnant state.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Gg Ferrimagnetics
75.30.Gw Magnetic anisotropy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
Page 2 of 26 Pages Return to All Sections Previous Page Next Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close