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Magnetics, IEEE Transactions on

Issue 2 • Date Feb. 2010

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Displaying Results 1 - 25 of 139
  • [Front cover]

    Publication Year: 2010 , Page(s): C1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2010 , Page(s): C2
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  • Table of contents

    Publication Year: 2010 , Page(s): 157 - 167
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  • Soft Magnetic Materials 19 Conference Co-Chairs' Foreword

    Publication Year: 2010 , Page(s): 168
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  • Soft Magnetic Materials 19 Publication Chair's Preface

    Publication Year: 2010 , Page(s): 169 - 170
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  • Soft Magnetic Materials 19 Conference

    Publication Year: 2010 , Page(s): 171
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  • Magnetic Normal Modes in Squared Antidot Array With Circular Holes: A Combined Brillouin Light Scattering and Broadband Ferromagnetic Resonance Study

    Publication Year: 2010 , Page(s): 172 - 178
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (963 KB) |  | HTML iconHTML  

    We present a combined experimental investigation of magnetic normal modes in an antidot lattice using both Brillouin light scattering and broadband ferromagnetic resonance. It was fabricated on a silicon substrate using optical ultraviolet lithography. The sample consisted of a 30-nm-thick Ni80Fe20 squared antidot array with circular holes whose diameter and edge-to-edge spacing are 250 and 150 nm, respectively. Experiments were performed as a function of the applied magnetic field ¿0Hext in the range from -100 to 100 mT, with Hext applied along both the square lattice axis and its diagonal. Several peaks were observed in both the Brillouin light scattering and ferromagnetic resonance spectra, and their evolution with the intensity and the direction of the applied field Hext was measured. Micromagnetic simulations enabled us to identify the modes in terms of their symmetry obtaining a good quantitative agreement with the measured frequencies. In addition, we show how the inhomogeneity of the internal field affected the properties of the magnetic eigenmodes and their localization in different regions of the antidot lattice. View full abstract»

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  • Influence of Different Onion States on Magnetization Reversal Processes in Permalloy Rings

    Publication Year: 2010 , Page(s): 179 - 182
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB) |  | HTML iconHTML  

    Simulation and experiment are performed to investigate the influence of onion states with different-helicity pair vortices on the magnetization reversal process. It is found that for the onion state that has pair vortices with the same helicity, flux-closure state occurs in the reversal process; for the onion state that has pair vortices with opposite helicity, flux-closure state does not occur in the reversal process, and the onion state transforms directly to the reverse onion state. In addition, notches at the same side and diagonal notches with respect to the field direction are designed on the permalloy rings to induce onion states with same-helicity pair vortices and opposite-helicity pair vortices, respectively, for the control of the three-step and two-step magnetization reversal processes. View full abstract»

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  • Analysis of Losses in a Magnetostrictive Device Under Dynamic Supply Conditions

    Publication Year: 2010 , Page(s): 183 - 186
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (627 KB) |  | HTML iconHTML  

    This paper, starting from previous experiences in modeling the magneto-mechanical behavior of magnetoelastic materials, faces the problem of loss evaluation of a magnetostrictive device. Measurements and simulations in a prototype actuator are here presented and compared, showing a general good agreement. The model is consequently used for a reliable loss separation. The effects of magnetization bias, preload and supply frequency on electric and magnetic losses are deepened and discussed. View full abstract»

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  • Comparison of Magnetic Field Analysis Methods Considering Magnetic Anisotropy

    Publication Year: 2010 , Page(s): 187 - 190
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB) |  | HTML iconHTML  

    The magnetic field analysis results on grain-oriented silicon steel sheet and nongrain-oriented silicon steel sheet by the isotropic method, the two-axis isotropic method, the two-axis anisotropic method, the ¿ anisotropic method, and the ¿HB anisotropic method, which are 2-D magnetic analysis methods, are compared. In analyzing the magnetic field in the isotropic material, the isotropic method is more appropriate than the two-axis isotropic method. For the anisotropic material in which the magnetic flux density is much less than saturation magnetic flux density, the two-axis anisotropic method is more preferable than the ¿ anisotropic method, because the result of the two-axis anisotropic method is similar to that of the ¿HB anisotropic method. However, for the analysis in high magnetic flux density near the saturation magnetic flux density, the ¿ anisotropic method is more suitable than the two-axis anisotropic method. View full abstract»

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  • A Low-Field Scaling Rule of Minor Hysteresis Loops in Plastically Deformed Steels

    Publication Year: 2010 , Page(s): 191 - 194
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    A scaling rule of magnetic minor hysteresis loops at low applied fields has been examined in plastically deformed low carbon steel and pure Ni. It was found that a power law between hysteresis loss and remanence of a minor loop holds true over the wide range of magnetization from the very low to intermediate range unlike the well-known Steinmetz law. The power-law exponent was an almost constant value of 1.35 being independent of the types of magnetic materials, the level of plastic deformation, and sample shape. The coefficient of the scaling rule increases with deformation and is in linear proportion to coercivity. This behavior was qualitatively explained on the basis of the Rayleigh law and NE¿el theory. View full abstract»

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  • Enhancement and Correlation of MFM Images: Effect of the Tip on the Magnetic Configuration of Patterned Co Thin Films

    Publication Year: 2010 , Page(s): 195 - 198
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1644 KB) |  | HTML iconHTML  

    A technique of numerical treatment of magnetic force microscopy (MFM) data matrices has been exploited to enhance the quality of raw MFM images of patterned Co thin films obtained by electron beam lithography on RF sputtered 30-nm-thick Co samples. The pattern consists of chains of elliptical cylinders whose major axis is around 2.5 ¿ m and whose minor axis is around 0.5 ¿m (aspect ratio 5:1). In this work, a new differential approach is proposed. Two or more MFM images of the same surface area of a soft ferromagnetic material submitted to different magnetic fields H are examined, and the different arrangements of the local magnetization, as emerging from contrast differences in MFM images, are analyzed as functions of H. It is shown that this differential approach is able to account for the effect of the MFM tip on the magnetization of the investigated soft magnetic material. The patterned Co samples used to demonstrate this method have been demagnetized before each MFM scan in the plane of the film by applying an alternate field of progressively small absolute value.RF sputtered samples. View full abstract»

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  • Spin Modes in Elliptical Nanorings in the Vortex State: Two-Dimensional Mapping by Micro-Focused Brillouin Light Scattering

    Publication Year: 2010 , Page(s): 199 - 202
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    Micro-focused and conventional Brillouin light scattering techniques have been exploited to investigate the spectrum of magnetic excitations (eigenmodes) of elliptical permalloy nanorings in the vortex ground state. The interpretation of the experimental data has been achieved using the dynamical matrix method. A careful comparison of the calculated frequency and profiles of magnetic modes with the experimental data, allowed us to identify the character of the different modes in terms of spatial symmetry and localization. In particular, the spatial extent of each mode was directly visualized by measurement of two-dimensional maps of the mode intensity over the ring surface. View full abstract»

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  • Effect of Surface Microstructure on Magnetization Process in Fe _{80.5} Cu _{1.5} Si _{4} B _{14} Nanocrystalline Alloys

    Publication Year: 2010 , Page(s): 203 - 206
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB) |  | HTML iconHTML  

    The magnetization processes of the Fe80.5Cu1.5Si4B14 nanocrystalline alloy were observed by Kerr effect. In the specimen annealed with heating rate of 0.3°C/s (NA), the pinning of domain walls was observed. Owing to such pinning effect in the NA specimen, high remanent magnetic flux density Br was obtained, and the hysteresis was observed in the B-H loop in the region of B > 1.5 T. Whereas, the smooth domain wall displacement was observed in the specimen annealed with the heating rate of 3°C/s (HA). The coarser grains near the surface observed in the NA specimen are considered to be the pinning site of the domain walls. In the HA specimen, grain growth in the heating process of annealing is suppressed. View full abstract»

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  • Stabilization of the Barkhausen Noise Parameters

    Publication Year: 2010 , Page(s): 207 - 209
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    The Barkhausen noise was measured in nonoriented Fe-3%Si steel with different average grain sizes. Air gaps between the yoke and the measured objects were also varied during the measurements. The change of the grain size was achieved by different combinations of cold rolling and heat treatment processes. The rise of the gap size degraded the level of the Barkhausen noise and caused that the parameters of the Barkhausen noise, such as the amplitude of the Barkhausen noise's envelope, decreased. In order to suppress the influence of the air gap size on the measurement results, we analyzed the amplitude probability distribution of the Barkhausen noise and we found that the distribution at small levels of the voltage practically does not change with the grain size, but it increases with rise of the gap size. This change of the amplitude probability distribution with the gap size was used to correct the amplitude of the Barkhausen noise's envelope. It was shown that the correction essentially increases the precision of the evaluation of the grain size at varying air gap. Similar technique can be used also to decrease the error of evaluation of other microstructural changes of ferromagnetic materials using the Barkhausen noise method, without measuring and feedback setting the defined waveform of the magnetic field in the sample. For this method to be applicable, several conditions should be met, especially the level of the Barkhausen noise should be essentially higher than the level of the disturbing noise. View full abstract»

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  • Domain Wall Dynamics in Thin Magnetic Wires Under the Influence of Transversal Magnetic Field

    Publication Year: 2010 , Page(s): 210 - 212
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB) |  | HTML iconHTML  

    We have studied the domain wall dynamics in thin amorphous glass-coating microwires under the influence of both axial and transversal magnetic fields. Two different regions of domain wall dynamics have been found according to the amplitude of the applied magnetic field rotated out of the wire's axis. At low amplitude, the effect of applied field rotation is reduced to the reduction of its axial component and the domain wall velocity decreases. For high amplitudes of magnetic field, the maximum velocity was found when applied field forms angle -20° with the wire's axis. The results are explained in terms of different domain wall structure, being transversal for low amplitudes of magnetic field and vortex for high amplitude of applied magnetic fields. View full abstract»

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  • Dimensional Effects on Magnetic Properties of Fe–Si Steels Due to Laser and Mechanical Cutting

    Publication Year: 2010 , Page(s): 213 - 216
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (884 KB) |  | HTML iconHTML  

    Microstructural deterioration near the cut line and presence of residual stresses both affect the magnetic properties of cut parts. In this paper, the differences between microstructural deterioration resulting from mechanical and laser cutting as well as the sample size effects observed upon hysteresis will be discussed. It will be shown that the underlying mechanism for changes in magnetic properties due to mechanical cutting is distinct from that of laser cutting. View full abstract»

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  • Spontaneous Domain Wall Motion at Zero External Magnetic Field in Ferromagnetic Nanowire

    Publication Year: 2010 , Page(s): 217 - 219
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (302 KB) |  | HTML iconHTML  

    We have explored a spontaneous domain wall motion in ferromagnetic nanowire at zero external magnetic field by means of micromagnetic simulation. Very interestingly, even with no external magnetic field, a spontaneous domain wall motion is observed with a speed about few tens of m/s, which is significant and not negligible in analysis of the domain wall dynamics on nanowires. The spontaneous zero-field wall motion is explained based on the minimization condition of the magnetostatic energy, preferring to have a wire magnetically saturated. Average speed of the spontaneous wall motion is found to increase as the wire thickness increases. View full abstract»

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  • A Mesoscopic Hysteresis Model Based on the Unconstrained Minimization of the Gibbs Free Energy

    Publication Year: 2010 , Page(s): 220 - 223
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB) |  | HTML iconHTML  

    Mesoscopic hysteresis models are based on a simplified description of the micromagnetic theory in order to simulate magnetization processes on the magnetic domain space scale. Hence, these models are situated between the micromagnetic and macroscopic models. In the presented mesoscopic description, the local magnetization is assumed to be aligned with either the cubic anisotropy axes or with the applied field. In this framework, the magnetization dynamics result from a constrained minimization of the Gibbs free energy. The numerical solution of this constrained minimization problem is highly time consuming. This paper presents a remapping of the model variables, which transforms the constrained minimization problem to an unconstrained problem and consequently results in a speed up and stabilization of the numerical scheme. Moreover, a model parameter analysis is carried out to further optimize the computational burden of the presented unconstrained procedure. View full abstract»

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  • Micromagnetic Simulation of Damped Oscillatory Behavior of Domain Wall Propagation in Sinusoidal Ferromagnetic Nanowire

    Publication Year: 2010 , Page(s): 224 - 227
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (395 KB) |  | HTML iconHTML  

    We have investigated a damped oscillatory behavior of domain wall propagation in wavy nanowires under an external field higher than the Walker breakdown field using micromagnetic simulation. In nanowires having sinusoidal edge distortions with variation of wavelengths, domain wall has been observed to pseudomorphically follow the sinusoidal wires with keeping an intrinsic transformational frequency of inner wall spin structure. Oscillation amplitude of the domain wall position decreases as the wavelength of the wire decreases by an interaction between the periodically distributed spins and the propagating domain wall. Oscillatory behavior of the domain wall position is found to decay in a wire having the wavelength well matching with an intrinsic transformational frequency of the propagating domain wall. View full abstract»

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  • Effect of Dipolar Interactions for Domain-Wall Dynamics in Magnetic Thin Films

    Publication Year: 2010 , Page(s): 228 - 230
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    We study the effect of long-range dipolar forces on the dynamics and morphology of domain walls in magnetic thin films by numerical simulations of the spin-1 random-field Ising model. By studying the size distribution of avalanches of domain-wall motion arising as a response to quasistatic external driving, we observe a crossover from the case dominated by short-range interactions to another universality class where the long-range dipolar forces become important. This crossover is accompanied with a change of the domain-wall morphology from a rough wall to walls with a zigzag structure. View full abstract»

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  • Domain Structure in (NiFe/Au/Co/Au) _{10} Multilayers With Perpendicular Anisotropy of Co Layers

    Publication Year: 2010 , Page(s): 231 - 234
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1288 KB) |  | HTML iconHTML  

    Results of domain structures observation of individual Ni80Fe20 and Co sublayers in sputter deposited (NiFe/Au/Co/Au)10 multilayers, using an element-sensitive method: the photoemission electron microscopy combined with soft X-ray magnetic circular dichroism, are presented. Also, overall domain structures were studied with magnetic force microscopy. The studies allowed us to reveal submicron stripe domains in the investigated samples and the replication of the stripe domains from the Co layers with perpendicular anisotropy to the NiFe layers with easy-plane anisotropy. View full abstract»

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  • Observation of a Transition From Inverse-Spin-Switch to Spin-Switch Behavior in Domain State of a Py/Nb/Py Trilayer

    Publication Year: 2010 , Page(s): 235 - 238
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (329 KB) |  | HTML iconHTML  

    We study spin switch behavior of the six bridges of bare, or pseudo spin-valve Py/Nb/Py trilayer prepared on a single chip. Magnetization measurement of both longitudinal and transverse moment on a large companion sample reveals that a significant amount of transverse component exists in the antiparallel domain (AD) state, which is originated in stray magnetic field from domain walls. The stray magnetic field induces flux lines into the Nb layer and the motion of these flux lines under the force exerted by the bias current is the main origin for inverse spin switch effect observed in the AD state of most bridges. In addition to inverse spin switch effect, we observe a peculiar behavior of a transition from inverse spin switch to spin switch behavior with decreasing temperature in one of six bridges. In order to understand the extraordinary behavior, we first note that the flux pinning should be present in this particular sample to suppress the dissipation by flux motion, then we propose that when the domain structure incidentally matches underlying distribution of pinning sites, spin switch effect in the AD state can occur by domain wall superconductivity and/or proximity effect. View full abstract»

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  • Evaluation of Barkhausen Noise and Magnetoacoustic Emission Signals Properties for Plastically Deformed Armco Iron

    Publication Year: 2010 , Page(s): 239 - 242
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1027 KB) |  | HTML iconHTML  

    The paper presents the results of the investigation of the influence of different modes of plastic deformation on the magnetoacoustic properties of Armco iron. Two sets of samples have been investigated-the first one consisted of preannealed samples that had been subsequently cold rolled, and the second one consisted of samples cut out from commercially available Armco plates, subjected to tensile loading. The process of cold rolling leads to the broadening of the envelopes and to the appearance of the third central peak [attributed to the domain-wall (DW) pinning]. In the case of the nonannealed samples, the Barkhausen envelope for the as-received sample reveals one, broad maximum that is transformed by the following tensile deformation initially into two and then three peaks. In order to detect subtle changes of the Barkhausen noise (BN) properties, a multiparameter [fast Fourier transform (FFT), pulse height distribution, wavelet transform] analysis was performed. As for the magnetoacoustic emission (MAE) signal, both deformation modes result in visible increase in peak separation as well as in the increase of the MAE intensity. As for the peak separation, it can be understood as the result of both the increase of the coercivity of the samples and the decrease of the slope of the B(H) loops since the MAE signal is generated mainly during creation/annihilation of DW occurring mainly at the "knee" regions of the B(H) loops. View full abstract»

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  • Numerical Analysis of the Influence of Geometry and Temperature on Switching Processes in Magnetic Nanostrips

    Publication Year: 2010 , Page(s): 243 - 246
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    The present paper numerically investigates the micromagnetic behavior of permalloy nanostrips, starting from the space-time integration of the Landau-Lifshitz-Gilbert equation. The analysis is performed on objects with variable longitudinal size of the order of some hundreds of nanometers. The attention is focused on the role of geometrical properties (e.g., scaling factor and end shape) and of thermal agitation on magnetization reversal processes. The thermal effects are included in the model following the Langevin approach. 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