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Magnetics, IEEE Transactions on

Issue 5  Part 2 • Date Sept. 1997

 This issue contains several parts.Go to:  Part 1  | Part 3 

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Displaying Results 1 - 25 of 258
  • Magnetic anisotropy of [Ni/sub 80/Fe/sub 20//Mo/Co] spin-valve films grown by MBE

    Publication Year: 1997 , Page(s): 3952 - 3954
    Cited by:  Papers (8)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB)  

    Nigh-quality spin-valve trilayers [Ni80Fe20Mo/CO] have been grown on MO buffer layer on MgO (110) and MgO (100) substrates by MBE. Structure and orientation relationships were determined by XRD and RHEED. The LMOKE studies show that both CO and Ni80Fe20 layers exhibit uniaxial magnetic anisotropy for a trilayer grown on MgO (110). On the other hand, nearly isotropic behaviors for the CO and Ni80Fe20 layers have been observed for a sample grown on MgO (100). The difference of magnetic anisotropies in the two systems mainly results from the magnetocrystalline effect. View full abstract»

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  • Conference Author Index

    Publication Year: 1997 , Page(s): 4275 - 4284
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    Freely Available from IEEE
  • Formation and magneto-structural properties of the new Nd3 Fe29-xWx intermetallic phase

    Publication Year: 1997 , Page(s): 3847 - 3849
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    This work reports the existence of the new ternary phase Nd3 Fe29-xWx (monoclinic, prototype Nd3 (Fe,Ti)29), opening the perspective of a W-stabilized family of compounds. Alloys with starting composition Nd3Fe 27.5W1.5 were prepared by argon arc melting from pure elements. As-cast ingots were wrapped in tantalum foils and annealed at 1100°C during three weeks followed by quenching in water. The homogeneous region of the best sample was characterized by structural and magnetic measurements. X-ray diffraction patterns were analyzed by the Rietveld method. For the 3:29 structure the space group A2/m was successfully assumed. The analysis shows that Nd3(Fe,W)29 is the main phase (73 wt.%) with lattice parameters a=10.615(2) Å, b=8.588(2) Å, c=9.754(2) Å and β=96.74(1)0. It co-exists with Nd2(Fe,W)17 (25 wt.%) and α-(Fe,W) (2 wt.%). The thermomagnetic curve of the specimens shows well defined transitions at 72°C and 123°C, which we attribute to the 2:17 and 3:29 phases, respectively. The composition of the 3:29 compound, measured by EDAX analysis, is Nd10.1Fe85.6W4.3. The average composition of the homogeneous region, calculated from the composition (measured by EDAX analysis) and weight fractions (calculated by Rietveld analysis of the XRD patterns) of the phases, is Nd10.1 Fe86.0W3.9. In addition, a small amount of α-(Fe,W) is detected. The saturation magnetization was estimated as 102 emu/g. The temperature dependence of the saturation magnetization and AC susceptibility are reported. The latter shows a magnetic anomaly at 259 K which suggests the existence of a spin reorientation transition View full abstract»

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  • Design of a dual moving-magnet motor for a hard disk drive actuator

    Publication Year: 1997 , Page(s): 3871 - 3873
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    This paper presents the design and the measured performance of a moving-magnet motor intended to drive a high bandwidth actuator assembly. The motor includes two magnets which are arranged to provide mainly torque rather than force. As a reference point, measurements are also made on a conventional moving coil actuator from a commercial 3.5" hard disk drive. The dual moving-magnet actuator is found to have better electromechanical characteristics and to be more power effective than the reference actuator View full abstract»

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  • Amorphous wire delay lines used for magnetic field measurements

    Publication Year: 1997 , Page(s): 4041 - 4043
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    In this paper we report some results concerning the dependence of the pulsed voltage output on the exciting magnetic field and on the bias magnetic field applied at the exciting or receiving point, for Fe77.5Si7.5B15 amorphous wires used as delay lines. The obtained results show a strong dependence of the pulsed voltage output on the values of the magnetic fields. Magnetic fields up to about 2000 A/m applied at the receiving point can be detected. Small magnetic fields applied at the exciting point can be detected using small values of the exciting magnetic field. Using this technique magnetic field sensors with high accuracy and sensitivity and absence of hysteresis can be realized. Such sensors can be formed in integrated arrays measuring the distribution of the magnetic field along the magnetostrictive delay line axis View full abstract»

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  • Texture study of magnets made from anisotropic HDDR powders

    Publication Year: 1997 , Page(s): 3832 - 3834
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    The texture in magnets made from NdFeB anisotropic HDDR powders was examined using an inverse pole figure and (006) pole figure. Unlike anisotropic magnets made by hot deformation, the magnets produced in the present study did not show a strong preferred orientation. The (006) pole figure of these magnets shows a weak (006) texture in contrast to that observed for the anisotropic magnets made by the hot deformation process. TEM studies carried out on these samples indicate that they contain some grains which have grown bigger than the adjacent small grains. Alignment of flakes with large grains in an applied magnetic field makes these magnets made from HDDR powders anisotropic View full abstract»

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  • Generation of uniform high fields with magnetized wedges

    Publication Year: 1997 , Page(s): 3874 - 3876
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    The properties of permanent magnets composed of uniformly magnetized wedges are presented in this paper. The magnets are fully open structures capable of generating strong fields exceeding the remanence of the material View full abstract»

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  • Magnetic flux sensing principle of microstrip pickup coil

    Publication Year: 1997 , Page(s): 4044 - 4046
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    We investigated the operating mechanism of the microstrip-line type pickup coil used for thin-film permeance measurements up to GHz range. We found that some flux lines form continuous loops around the ground plane when the coil has a sample window. How the flux distribution changes and how the induced voltage increases when a magnetic sample is inserted was clarified by measurements of flux distribution and finite element calculations View full abstract»

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  • Magnetic and structural properties of Sm2Fe10Co7/MxCy thin films

    Publication Year: 1997 , Page(s): 3703 - 3705
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    The structural and magnetic properties of Sm2Fe10 Co7/MxCy (M=Al and Si; x⩾0 and y⩾0) multilayer films with Ta underlayers and overlayers before and after annealing at 700°C for 5-12 min have been fabricated and studied. Structural studies show evidence of layer diffusion upon annealing. X-ray diffraction shows that the samples after annealing consist of a soft phase, α-Fe, and a hard phase with the 2-17-type structure. The samples studied have in-plane anisotropy with single hysteresis loops indicating that the two phases are strongly exchange coupled. After annealing, the coercivity of samples with AlxC y is found to increase with increasing AlxCy composition to a maximum of 3.3 kOe. The energy products for these samples are found to increase from 1.4 MGOe for SmFeCo to 8 MGOe for SmFeCo with AlxCy View full abstract»

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  • GMR of Co/Cu multilayers with reduced hysteresis and low-field response

    Publication Year: 1997 , Page(s): 3532 - 3534
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    We present results of a study on optimization of the magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for Cu layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t(1)Co) and thin (t(2)Co ) Co layers have been prepared in the form of [Cot(1) Co Å/Cu20 Å/Cot(2)Co Å/Cu20 Å]15. We have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t (2)Co and has disappeared when t(2)Co<4.5 Å. We have obtained an optimal GMR response with a field sensitivity of 0.13%/0e over a field region of ~60 Oe centered at ~50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications View full abstract»

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  • Reduction of iron loss in thin grain-oriented silicon steel sheets

    Publication Year: 1997 , Page(s): 3754 - 3756
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    We investigated the effect of the intermediate annealing conditions on the grain textures and the magnetic properties in thin grain-oriented silicon steel sheets produced by the three-stage rolling method. It was found that the lower the intermediate annealing temperature is, the better the [001] orientation is achieved. In addition, the reduction of the intermediate annealing temperatures improves dc magnetic properties (B8, Hc) and enables to reduce the iron loss in thin silicon steels. The measured iron loss W13/50 under the applied tensile strength of 2 kg/mm2 was 0.28 W/kg, which is less than that of the conventional (300 μm) grain-oriented silicon steels by about 50% View full abstract»

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  • Switching characteristics of submicron dimension Permalloy sandwich films

    Publication Year: 1997 , Page(s): 3601 - 3603
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    Submicron magnetoresistive sandwich cells of various sizes are fabricated and their magnetic properties are studied. A novel coupling mechanism of magnetostatic origin has been found to be mainly responsible for unique switching characteristics in cells with small length to width ratio View full abstract»

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  • Giant magnetoresistance in melt-spun Cu80Ni16Fe4 ribbons

    Publication Year: 1997 , Page(s): 3562 - 3564
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    We present the magnetoresistance and magnetization behavior in melt-spun Cu80Ni16Fe4 ribbons. The as-spun ribbon exhibits magnetoresistance (MR) ratios of 13% and 0.1% at 5 K and room temperature, respectively. The MR behavior of the ribbon is found to be mostly related to the magnetic fluctuation scattering at temperatures well above the blocking temperature and the spin-dependent scattering at lower temperatures. The latter mechanism can be understood in terms of the blocking of small magnetic particles and paramagnetic-ferromagnetic transformation at lower temperatures, as supported by the magnetization data. When the microstructure is modified by proper heat treatment, the ribbon exhibits significant giant magnetoresistance behavior both at room temperature and 5 K View full abstract»

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  • Consolidation, magnetic and mechanical properties of gas atomized and HDDR Nd2Fe14B powders

    Publication Year: 1997 , Page(s): 3835 - 3837
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    Nd2Fe14B powders produced by gas atomization (GA) were consolidated and the fracture toughness and magnetic properties were measured and compared to material produced by hydrogenation, disproportionation, desorption, and recombination (HDDR) and to Magnequench MQII magnets. Hot pressing of the gas atomized powder without TiC additions required temperatures and times similar to that required by Magnequench melt spun powder. Titanium plus carbon additions, which result in enhanced quenchability during production of the GA powder, required higher temperatures than alloys without TiC for successful hot pressing and full densification. However, grain sizes remained under 50 nm in the consolidated magnet. Toughnesses for both HDDR and GA material with the larger powder sizes were slightly higher than those of comparable MQII specimens. The TiC modified GA material may result in tougher magnets that are easier to process at higher temperatures by techniques such as extrusion View full abstract»

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  • Smoother thrust on multi-polar type linear DC motor

    Publication Year: 1997 , Page(s): 3877 - 3879
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    As compared with a mono-polar type linear DC motor (LDM), multi-polar type LDM can have a longer stroke and more thrust with thin shape. However, there is thrust ripple on the multi-polar LDM. In this paper, a design to prevent thrust ripple is discussed. In order to achieve smoother thrust on multi-polar type LDM, the structure of the LDM is set as a 2-phase coil type. This paper clarifies that the thrust ripple of the LDM has a minimum value of 1.68%, a pole pitch of 15 mm, a coil width of 12 mm and a permanent magnet width of 10 mm View full abstract»

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  • Magnetic resonance force microscopy with a permanent magnet on the cantilever

    Publication Year: 1997 , Page(s): 4047 - 4049
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    When the variation of the bias field is on the order of a few hundred gauss, permanent magnetic microparticles of Nd2Fe14B (NdFeB) mounted on atomic force microscopy (AFM) cantilevers generate much smaller nonresonance (NR) signals in the magnetic resonance force microscopy (MRFM) spectra than most soft magnetic thin films. However, the interactions of the NdFeB particle with the bias field cause an undesirable variation of the cantilever resonance frequency with changing bias field. Our model indicates the importance of minimizing the polarized moment of the magnetic tip and ensuring that the applied fields employed in the MRFM experiment be highly uniform View full abstract»

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  • The corrosion protection of RE-iron-boron magnets by a phosphate treatment

    Publication Year: 1997 , Page(s): 3907 - 3909
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The effect of a phosphate treatment as a corrosion inhibitor for a RE-iron-boron magnet has been investigated. The corrosion characteristics of the magnet in a phosphate solution, which consisted of 0.15 M NaH2PO4, were analyzed by electrochemical impedance and electrochemical noise measurements. The immersion of the magnet in the phosphate solution resulted in the formation of a passive layer on its surface causing a prolonged corrosion protection, after removal from the solution. The protective layer was found to consist of phosphate/pyrophosphate and oxide by XPS analysis View full abstract»

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  • High coercivity SmFeAlC thin films fabricated by multilayer sputtering

    Publication Year: 1997 , Page(s): 3706 - 3708
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    Multilayer sputtering of SmFe/C(Al) plus appropriate thermal processing has been used to fabricate SmFeC thin films with Al substitution for Fe. It was found that the SmFeAlC thin films exhibited exceptionally high coercivities. A coercivity of 28 kOe was realized for the thin film with structure of Ta(1000 Å)/[SmFe(40 Å)/C(Al)(5 Å)]×50/Ta(200 Å) with subsequent annealing at 650°C View full abstract»

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  • A neural network model of magnetic hysteresis for computational magnetics

    Publication Year: 1997 , Page(s): 4146 - 4148
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    A neural network to implement a hysteresis model for a magnetic material within a finite element program is described. It is shown that such a system can match the results produced by a Preisach model but the time overhead can be considerably reduced thus making feasible the solution of large problems involving hysteretic materials View full abstract»

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  • Ultrasound enhanced ferrite plating; bringing breakthrough in ferrite coating synthesized from aqueous solution

    Publication Year: 1997 , Page(s): 3649 - 3651
    Cited by:  Papers (17)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    Applying power ultrasound waves (19.5 kHz, 600 W) to 300 ml of FeCl2 aqueous solution (pH=7.0) at 70°C, we successfully encapsulated polyacrylate spheres of two sizes, 0.25 μm and 4.5 μm in average diameter, with ferrite coatings of a magnetite-maghemite mixed solution. This broke the previous lower limit (0.3 μm) of the size of the particles to be encapsulated; without application of the ultrasound waves, the ferrite coating became discontinuous or insular. The ultrasound waves produce on the polymer surfaces OH groups (which work as ferrite nucleation sites), and remove the isolated ferrite particles (grown from the solution) from the surface of the ferrite coatings. This improved the surface quality of the ferrite coatings. The ferrite-encapsulated particles will greatly improve the performance of the enzyme immunoassay, which has been put to clinical use as a cancer test reagent with insular-ferrite-coated particles View full abstract»

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  • Calculation of the magnetic behaviour of electrical steel sheet under two dimensional excitation by means of the reluctance tensor

    Publication Year: 1997 , Page(s): 3757 - 3759
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    A mathematical description of the non-linear and anisotropic behaviour of electrical steel sheet under two dimensional excitation is presented considering the field penetration into the bulk of the material. This description allows the calculation of the distribution of the magnetic field strength and the magnetic flux density for arbitrary two dimensional flux conditions in the cross section of the sheet. The calculation of the dynamic hysteresis loops and the loci of the magnetic field strength, respectively, by means of the proposed mathematical model shows very good agreement with the corresponding measurement results View full abstract»

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  • Energy-dependent hot electron transport across a spin-valve

    Publication Year: 1997 , Page(s): 3500 - 3504
    Cited by:  Papers (56)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    Hot electron transport across an Fe/Au/Fe spin valve was examined by measuring a collector current of a hot electron transistor which was composed of an Al/AlOx emitter, the spin-valve base and an nSi collector. The collector current changed more than 200% under application of magnetic field. The magnitude of this change decreased monotonously with emitter voltage, and no anomaly was observed at the voltage (~1.5 V) corresponding to the sharp peak in the density of states of the minority spin bands in Fe View full abstract»

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  • Magnetic clusters, intergranular exchange interaction and their microstructural basis in thin film longitudinal media

    Publication Year: 1997 , Page(s): 4074 - 4076
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    We have experimental examined the micromagnetic structure in CoCrTa/Cr films deposited onto NiP/Al substrates at 25, 100, 150 200 and 250°C. We prepared all the films in an ac-erased magnetic state. The Lorentz transmission electron microscopy images demonstrate a monotonic decrease of magnetic cluster size with increase of deposition temperature and the magnetic force microscopy results show a decrease of image contrast. This indicates a decrease of intergranular exchange coupling with increase of deposition temperature. Nanoprobe energy dispersive spectroscopy (EDS) reveals an increase of Cr segregation at CoCrTa grain boundaries with increase of deposition temperature. The correlation of micromagnetic and microcompositional observation supports that Cr segregation at grain boundaries is responsible for decoupling CoCrTa grains. Our nanoprobe EDS results also indicate that the Cr diffuses to the grain boundaries from the diffusion process involving the Cr underlayer View full abstract»

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  • The effect of magnetic field annealing on magnetic properties in ultrathin Fe-based nanocrystalline alloys

    Publication Year: 1997 , Page(s): 3799 - 3801
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    Ultrathin Fe78Al4B12Nb5Cu1 and Fe83B9Nb7Cu1 nanocrystalline ribbon alloys below 10 μm in thickness were annealed in transverse magnetic field, and then the high-frequency soft magnetic properties and their compositional effect were investigated. Very high effective permeability and excellent magnetic core loss characteristics in MHz range were obtained for both alloys after optimum annealing. However, the Al-added alloy was more sensitive to the magnetic field annealing and much improved soft magnetic properties in the high frequency range were revealed View full abstract»

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  • Simulation of 3-D micromagnetic structures in thin iron platelet

    Publication Year: 1997 , Page(s): 4170 - 4172
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The three dimensional classical Landau-Lifshitz domain structure in a 30 nm thick (100) iron rectangular platelet was simulated by a 3-D extension of the LaBonte method. Two stable micromagnetic structures with different symmetries and energies were obtained. The four 90° walls of both the structures are of the simple symmetric Neel type. However, the single 180° domain walls in the centres of the two structures have different complicated 3-D cross-tie periodic structures containing circular swirls and cross swirls which we believe correspond to the complicated zip-like patterns that have been observed by magnetic force microscopy. The period of the spacing of the swirls is comparable to that of these zip-like patterns. In addition to the 3-D simulation, 2-D simulations were also employed to study the variation in periodicity of the circular and cross swirls with the length of the platelet View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology