Materials Science › Electronic, Optical and Magnetic Materials

Magnetic Properties and Applications

Works Count: 66772

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Description

This cluster of papers focuses on the study of magnetostrictive properties, hysteresis modeling, and applications of magnetostrictive materials, particularly in Fe-Ga and Galfenol alloys. It also explores the impact of magnetostriction on core losses in electrical steels and transformer inrush currents. Additionally, it delves into the structural and magnetic behavior of these materials under various mechanical and thermal conditions.

Keywords

Magnetostriction; Magnetic Materials; Fe-Ga Alloys; Core Losses; Hysteresis Model; Electrical Steels; Transformer Inrush Currents; Galfenol Alloys; Ferroresonance; Terfenol-D

Quantum Theory of Magnetism

2007-01-01

Robert M. White

Introduction to magnetism and magnetic materials

2016-05-24

D. C. Jiles

ELECTROMAGNETISM: MAGNETIC PHENOMENA ON THE MACROSCOPIC SCALE Magnetic Fields Magnetic Field Magnetic Induction Magnetic Field Calculations References Further Reading Exercises Magnetization and Magnetic Moment Magnetic Moment Magnetic Poles and Amperian … ELECTROMAGNETISM: MAGNETIC PHENOMENA ON THE MACROSCOPIC SCALE Magnetic Fields Magnetic Field Magnetic Induction Magnetic Field Calculations References Further Reading Exercises Magnetization and Magnetic Moment Magnetic Moment Magnetic Poles and Amperian Bound Currents Magnetization Magnetic Circuits and the Demagnetizing Field Penetration of Alternating Magnetic Fields into Materials References Further Reading Exercises Magnetic Measurements Induction Methods Force Methods Methods Depending on Changes in Material Properties Superconducting Quantum Interference Devices References Further Reading Exercises Magnetic Materials Classification of Magnetic Materials Magnetic Properties of Ferromagnets Different Types of Ferromagnetic Materials for Applications Paramagnetism and Diamagnetism References Further Reading Exercises MAGNETISM IN MATERIALS: MAGNETIC PHENOMENA ON THE MICROSCOPIC SCALE Magnetic Properties Hysteresis and Related Properties Barkhausen Effect and Related Phenomena Magnetostriction Magnetoresistance References Further Reading Exercises Magnetic Domains Development of Domain Theory Energy Considerations and Domain Patterns References Further Reading Exercises Domain Walls Properties of Domain Boundaries Domain-Wall Motion References Further Reading Exercises Domain Processes Reversible and Irreversible Domain Processes Determination of Magnetization Curves from Pinning Models Theory of Ferromagnetic Hysteresis Dynamics of Domain Magnetization Processes References Further Reading Exercises Magnetic Order and Critical Phenomena Theories of Paramagnetism and Diamagnetism Theories of Ordered Magnetism Magnetic Structure References Further Reading Exercises Electronic Magnetic Moments Classical Model of Magnetic Moments of Electrons Quantum Mechanical Model of Magnetic Moments of Electrons Magnetic Properties of Free Atoms References Further Reading Exercises Quantum Theory of Magnetism Electron-Electron Interactions Localized Electron Theory Itinerant Electron Theory References Further Reading Exercises MAGNETICS: TECHNOLOGICAL APPLICATIONS Soft Magnetic Materials Properties and Applications of Soft Magnets Materials for AC Applications Materials for DC Applications Materials for Magnetic Shielding References Further Reading Materials Conferences Hard Magnetic Materials Properties and Applications of Hard Magnets Permanent Magnet Materials References Further Reading Materials Conferences Magnetic Recording History of Magnetic Recording Magnetic Recording Media Recording Heads and the Recording Process Modeling the Magnetic Recording Process References Further Reading Magnetic Evaluation of Materials Methods for Evaluation of Materials Properties Methods for Detection of Flaws and Other Inhomogeneities Magnetic Imaging Methods Sensitivity to Microstructure and Material Treatment References Further Reading Solutions to Exercises

Magneto-Structural Correlations in Exchange Coupled Systems

1984-01-01

R.D. Willett , Dante Gatteschi , Olivier Kahn

Physical Principles of Magnetism

1966-04-01

Gh. Adam

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<i>Introduction to the Theory of Ferromagnetism</i>

1997-09-01

Amikam Aharoni , A. S. Arrott

1.: Introduction. 2.: Molecular field approximation. 3.: The Heisenberg Hamiltonian. 4.: Magnetization vs. temperature. 5.: Anisotropy and time effects. 6.: Another energy term. 7.: Basic micromagnetics. 8.: Energy minimization. 9.: … 1.: Introduction. 2.: Molecular field approximation. 3.: The Heisenberg Hamiltonian. 4.: Magnetization vs. temperature. 5.: Anisotropy and time effects. 6.: Another energy term. 7.: Basic micromagnetics. 8.: Energy minimization. 9.: The nucleation problem. 10.: Analytic micromagnetics. 11.: Numerical micromagnetics. References. Index

Hall Effect in Ferromagnetics

1954-09-01

Robert Karplus , J. M. Luttinger

Both the unusually large magnitude and strong temperature dependence of the extraordinary Hall effect in ferromagnetic materials can be understood as effects of the spin-orbit interaction of polarized conduction electrons. … Both the unusually large magnitude and strong temperature dependence of the extraordinary Hall effect in ferromagnetic materials can be understood as effects of the spin-orbit interaction of polarized conduction electrons. It is shown that the interband matrix elements of the applied electric potential energy combine with the spin-orbit perturbation to give a current perpendicular to both the field and the magnetization. Since the net effect of the spin-orbit interaction is proportional to the extent to which the electron spins are aligned, this current is proportional to the magnetization. The magnitude of the Hall constant is equal to the square of the ordinary resistivity multiplied by functions that are not very sensitive to temperature and impurity content. The experimental results behave in such a way also.

Theory of helical magnetic structures and phase transitions in MnSi and FeGe

1980-11-10

Per Bak , Mogens H. Jensen

The long-period helical magnetic structures in MnSi and FeGe are shown to be consequences of a ferromagnetic Dzyaloshinskii instability (1964). Renormalisation group theory predicts the transition to be first order, … The long-period helical magnetic structures in MnSi and FeGe are shown to be consequences of a ferromagnetic Dzyaloshinskii instability (1964). Renormalisation group theory predicts the transition to be first order, in agreement with experiments on MnSi.

Theory of the Structure of Ferromagnetic Domains in Films and Small Particles

1946-12-01

C. Kittel

The theory is developed of the domain structure of ferromagnetic bodies whose smallest dimension is comparable with the thickness of the Weiss domains as found in crystals of ordinary size. … The theory is developed of the domain structure of ferromagnetic bodies whose smallest dimension is comparable with the thickness of the Weiss domains as found in crystals of ordinary size. Calculations of the domain boundary, magnetic, and anisotropy energies of various domain configurations are given for thin films, small particles, and long needles of ferromagnetic material. For sufficiently small dimensions the optimum structure consists of a single domain magnetized to saturation in one direction. This result implies unusual magnetic characteristics, such as have in fact been reported by a number of experimenters. The critical dimensions for transition from a configuration with domain structure to a saturated configuration are estimated \ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ cm in films and \ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ cm in particles or grains. These estimates are based on typical values of the relevant material constants, and may be increased or decreased by a factor of ten for other values of the constants.

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Physical Theory of Ferromagnetic Domains

1950-08-15

L. W. McKeehan

General properties of power losses in soft ferromagnetic materials

1988-01-01

G. Bertotti

Measurements are reported of the loss per cycle (sinusoidal flux waveform) versus magnetizing frequency f/sub m/(0<or=f/sub m/<or=100 or 400 Hz) and peak magnetization I/sub max/, performed on 3% SiFe alloys … Measurements are reported of the loss per cycle (sinusoidal flux waveform) versus magnetizing frequency f/sub m/(0<or=f/sub m/<or=100 or 400 Hz) and peak magnetization I/sub max/, performed on 3% SiFe alloys (both grain-oriented and nonoriented), Armco iron, NiFe alloys, and amorphous ribbons. Using a novel theoretical framework, the microscopic origin of the observed dynamic losses is discussed, and a physical interpretation is given of the general fact that the loss per cycle is always a nonlinear function of f/sub m/. A theoretical procedure is discussed by which it is possible, for a generic material, given a single loss curve at a certain value of I/sub max/, to predict the dependence of dynamic losses on both I/sub max/ and f/sub m/, with an approximation within +or-10% in all the investigated cases. The behaviour of grain-oriented SiFe, which presents some specific complexities, is discussed in particular detail.<<ETX>>

Mathematical models of hysteresis

1986-09-01

I.D. Mayergoyz

A new approach to the scalar Preisach model of hysteresis, which emphasizes its phenomenological nature and mathematical generality, is described. The theorem, which gives the necessary and sufficient conditions for … A new approach to the scalar Preisach model of hysteresis, which emphasizes its phenomenological nature and mathematical generality, is described. The theorem, which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by the scalar Preisach model, is reported. The significance of this theorem is that it establishes the limits of applicability of Preisach's model regardless of the physical nature of hysteresis. Then, the vector Preisach models are formulated and some basic properties of these models are briefly summarized. Numerical implementations of Preisach's models are discussed and some computational results are given.

A model for alloying in ferromagnetic metals

1978-01-01

Mats Hillert , Magnus Jarl

Theory of ferromagnetic hysteresis

1986-09-01

David Jiles , D.L. Atherton

Anisotropie magnétique superficielle et surstructures d'orientation

1954-01-01

Louis Néel

Sommaire.2014 Dans la première partie de ce Mémoire, on propose de considérer l'énergie magnéto- cristalline et magnétoélastique d'un corps ferromagnétique comme la somme de termes élémentaires relatifs chacun à une … Sommaire.2014 Dans la première partie de ce Mémoire, on propose de considérer l'énergie magnéto- cristalline et magnétoélastique d'un corps ferromagnétique comme la somme de termes élémentaires relatifs chacun à une liaison, c'est-à-dire à un couple de deux atomes proches voisins.Sur cette base, on développe la théorie de la magnétostriction et de l'anisotropie magnétocristalline et, de sa comparaison avec les résultats expérimentaux, on déduit les valeurs des paramètres qui caractérisent l'énergie de liàison.Des mêmes prémices, on déduit qu'il doit exister dans les corps ferromagnétiques, une énergie d'anisotropie superficielle, dépendant de l'orientation de l'aimantation spontanée par rapport à la surface et ne présentant d'ailleurs aucun rapport avec le phénomène classique de champ démagnétisant de forme.Cette énergie de surface, de l'ordre de O, I à I erg/cm2, est susceptible de jouer un rôle important dans les propriétés des substances ferromagnétiques dispersées en éléments de dimensions inférieures à I00 Å.Dans la seconde partie, on montre, en adoptant le point de vue précédent, que dans les solutions solides ferromagnétiques à deux constituants au moins, traitées à chaud dans un champ magnétique, les atomes proches voisins d'un atome donné doivent se répartir d'une façon anisotrope autour de ce dernier et donner naissance à une surstructure d'orientation.Par trempe, cette surstructure est susceptible de se conserver en faux équilibre à basse température et se manifeste par l'apparition d'une anisotropie magnétique de caractère uniaxial.Les phénomènes sont précisés par le calcul, notam- ment le rôle de la concentration, dans le cas de différents réseaux cubiques simples et dans le cas d'une substance isotrope par compensation.L'anisotropie calculée est de l'ordre de I03 à I05 ergs/cm2, mais paraît dépasser largement ces valeurs dans des cas exceptionnels.Cette théorie rend compte des propriétés des ferronickels traités à chaud dans un champ magnétique et, en particulier, des mono- cristaux de permalloy.On suggère le rôle possible de ces effets dans l'alnico V et les ferrites de cobalt orientés.Dans une troisième partie, on montre que l'on peut créer une surstructure d'orientation dans une solution solide quelconque au moyen d'une déformation élastique à chaud et la conserver par trempe.Si la solution solide est ferromagnétique, les surstructures ainsi créées donnent naissance à une aniso- tropie magnétique de caractère uniaxial.En s'appuyant sur une théorie sommaire des propriétés élastiques des solutions solides développée à cet effet, le phénomène est soumis au calcul : on trouve des anisotropies de I04 ergs/cm3 pour des tensions de I0 kg/mm2, dans le cas des ferronickels.On propose d'interpréter par la création de telles surstructures l'anisotropie magnétique uniaxiale des ferro- nickels quasi unicristallins laminés à froid, la déformation plastique permettant aux atomes de prendre la répartition d'équilibre correspondant au système des tensions appliquées.Dans les ferronickels polycristallins laminés ou étirés, l'anisotropie est de signe contraire à la précédente; on propose de l'expliquer selon le même mécanisme que les phénomènes de restauration après fluage.TOME la.% N° ~.AVRIL à 195li., Introduction.

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Numerical determination of hysteresis parameters for the modeling of magnetic properties using the theory of ferromagnetic hysteresis

1992-01-01

David Jiles , J.B. Thoelke , M. K. Devine

The authors describe how the various model parameters needed to describe hysteresis on the basis of the Jiles-Atherton theory can be calculated from experimental measurements of the coercivity, remanence, saturation … The authors describe how the various model parameters needed to describe hysteresis on the basis of the Jiles-Atherton theory can be calculated from experimental measurements of the coercivity, remanence, saturation magnetization, initial anhysteretic susceptibility, initial normal susceptibility, and maximum differential susceptibility. The determination of hysteresis parameters based on this limited set of magnetic properties is of the most practical use since these are the properties of magnetic materials that are most likely to be available.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

Theory of ferromagnetic hysteresis (invited)

1984-03-15

David Jiles , D.L. Atherton

A mathematical theory of hysteresis in ferromagnetic materials is presented based on existing ideas of domain wall motion and domain rotation. Hysteresis is shown to occur as a result of … A mathematical theory of hysteresis in ferromagnetic materials is presented based on existing ideas of domain wall motion and domain rotation. Hysteresis is shown to occur as a result of impedances to changes of magnetization such as when domain walls are pinned, while the mutual interactions of the magnetic moments are shown to be of secondary importance in this respect. An equation for the anhysteretic or ideal magnetization curve is derived based on a mean field approximation and this is shown to be dependent on the mutual interactions of the moments but independent of impedances such as pinning. The introduction of a term which measures the impedance to changes in magnetization leads to a simple differential equation of state for a ferromagnet which exhibits all the features of hysteresis. Some modifications of the simple model are necessary in order to bring the solution closer to the real situation. Results are presented which show all the features of hysteresis such as initial magnetization curve, major hysteresis loops, and minor hysteresis loops in excellent agreement with experimental results.

Theory of the magnetomechanical effect

1995-08-14

David Jiles

This study investigated a model theory of the changes in magnetization that a ferromagnetic material undergoes when subjected to an applied uniaxial stress. The description of these effects is shown … This study investigated a model theory of the changes in magnetization that a ferromagnetic material undergoes when subjected to an applied uniaxial stress. The description of these effects is shown to be totally different from the description of the changes in the hysteresis curve under a series of constant applied stresses. The main mechanism in the proposed model theory is the unpinning of domain walls by the application of stress, which allows the walls to move and causes a change in the magnetization. This change in magnetization reduces the displacement from the anhysteretic magnetization. In addition, the anhysteretic magnetization itself is changed by the application of stress via the magnetoelastic coupling. It is shown that the effect can be described by an equation in which the rate of change of magnetization with elastic energy is proportional to the displacement of the magnetization from the anhysteretic magnetization. This is termed the 'law of approach'. This law seems to apply when the starting condition of the material is on a major hysteresis loop.

The motion of 180° domain walls in uniform dc magnetic fields

1974-12-01

N. L. Schryer , L. R. Walker

The equations of motion of a 180° domain wall in an infinite uniaxially anisotropic medium which is exposed to an instantaneously applied uniform dc magnetic field H0 have been integrated … The equations of motion of a 180° domain wall in an infinite uniaxially anisotropic medium which is exposed to an instantaneously applied uniform dc magnetic field H0 have been integrated numerically. Below the critical field Hc =2παM0 (α is the Gilbert loss parameter and M0 the saturation magnetization), where a steady-state solution is known to exist, it is shown that the wall motion tends smoothly to this solution. Above Hc, the magnetization precesses about the field and a periodic component appears in the forward motion of the wall. Analytic solutions for the wall motion have been found based upon approximations suggested by the computed behavior; these reproduce the computer results very accurately.

Beitrag zur Theorie des Ferromagnetismus

1925-02-01

Ernst Ising

Dispersion and absorption in magnetic ferrites at frequencies above one Mc/s

1948-05-01

J.L. Snoek

On the Theory of Ferromagnetic Resonance Absorption

1948-01-15

C. Kittel

The theory of ferromagnetic resonance absorption previously developed is extended to include the effect of the shape of the specimen and, in the case of a single crystal, the effect … The theory of ferromagnetic resonance absorption previously developed is extended to include the effect of the shape of the specimen and, in the case of a single crystal, the effect of crystal orientation. The resonance condition may be written ${\ensuremath{\omega}}_{0}=\ensuremath{\gamma}{H}_{\mathrm{eff}}$, where ${H}_{\mathrm{eff}}$ is equal to ${(\mathrm{BH})}^{\frac{1}{2}}$ for a plane surface, $H+2\ensuremath{\pi}M$ for a long circular cylinder, and $H$ for a sphere; the latter two values apply only to the situation in which the eddy current skin depth is large in comparison with the radius of the specimen. In the case of an uniaxial crystal with the axis parallel to the static magnetic field, the value of $H$ to be used in the resonance conditions is increased by $\frac{2K}{M}$, where $K$ is the anisotropy constant. The case of a cubic crystal is also considered. A detailed discussion of macroscopic eddy current effects is given, and it is shown that the usual eddy current losses do not introduce damping terms into the expression for the permeability, when properly interpreted.

Magnetostatic modes of a ferromagnet slab

1961-05-01

R. W. Damon , J. R. Eshbach

A Study of Magnetic Viscosity

1949-09-01

R. A. Street , J. C. Woolley

A general analysis of magnetic viscosity based on activation energy concepts is given. A particular case is considered of the application of the theory to the phenomenon occurring in materials … A general analysis of magnetic viscosity based on activation energy concepts is given. A particular case is considered of the application of the theory to the phenomenon occurring in materials in which bulk magnetization proceeds by the rotational movement of the vectors of single domains, which process, according to a recent theory of Stoner and Wohlfarth, may occur in certain high coercivity alloys. Experiments have been made, using a magnetometer method, with specimens of alnico maintained at various temperatures within the range - 187° c. to 250° c. The results obtained are found to be in good agreement with the theoretical analysis.

A mechanism of magnetic hysteresis in heterogeneous alloys

1948-05-04

Edmund C. Stoner , E.P. Wohlfarth

The Becker-Kersten treatment of domain boundary movements is widely applicable in the interpretation of magnetization curves, but it does not account satisfactorily for the higher coercivities obtained, for example, in … The Becker-Kersten treatment of domain boundary movements is widely applicable in the interpretation of magnetization curves, but it does not account satisfactorily for the higher coercivities obtained, for example, in permanent magnet alloys. It is suggested that in many ferromagnetic materials there may occur ‘particles’ (this term including atomic segregates or ‘islands’ in alloys), distinct in magnetic character from the general matrix, and below the critical size, depending on shape, for which domain boundary formation is energetically possible. For such single-domain particles, change of magnetization can take place only by rotation of the magnetization vector, I O . As the field changes continuously, the resolved magnetization, I H , may change discontinuously at critical values, H O , of the field. The character of the magnetization curves depends on the degree of magnetic anisotropy of the particle, and on the orientation of ‘easy axes’ with respect to the field. The magnetic anisotropy may arise from the shape of the particle, from magneto-crystalline effects, and from strain. A detailed quantitative treatment is given of the effect of shape anisotropy when the particles have the form of ellipsoids of revolution (§§ 2, 3, 4), and a less detailed treatment for the general ellipsoidal form (§ 5). For the first it is convenient to use the non-dimensional parameter such that h = H /(| N a - N b |) I O , N a and N b being the demagnetization coefficients along the polar and equatorial axes. The results are presented in tables and diagrams giving the variation with h of I H / I O . For the special limiting form of the oblate spheroid there is no hysteresis. For the prolate spheroid, as the orientation angle, θ , varies from 0 to 90°, the cyclic magnetization curves change from a rectangular form with | h O | = 1, to a linear non-hysteretic form, with an interesting sequence of intermediate forms. Exact expressions are obtained for the dependence of h θ on θ , and curves for random distribution are computed. All the numerical results are applicable when the anisotropy is due to longitudinal stress, when h = HI 0 /3λδ, where λ is the saturation magnetostriction coefficient, and δ the stress. The results also apply to magneto-crystalline anisotropy in the important and representative case in which there is a unique axis of easy magnetization as for hexagonal cobalt. Estimates are made of the magnitude of the effect of the various types of anisotropy. For iron the maximum coercivities, for the most favourable orientation, due to the magneto-crystalline and strain effects are about 400 and 600 respectively. These values are exceeded by those due to the shape effect in prolate spheroids if the dimensional ratio, m , is greater than 1·1; for m = 10, the corresponding value would be about 10,000 (§7). A fairly precise estimate is made of the lower limit for the equatorial diameter of a particle in the form of a prolate spheroid below which boundary formation cannot occur. As m varies from 1 (the sphere) to 10, this varies from 1·5 to 6·1 x 10 -6 for iron, and from 6·2 to 25 x 10 -6 for nickel (§ 6). A discussion is given (§ 7) of the application of these results to ( a ) non-ferromagnetic metals and alloys containing ferromagnetic ‘impurities’, ( b ) powder magnets, ( e ) high coeravity alloys of the dispersion hardening type. In connexion with ( c ) the possible bearing on the effects of cooling in a magnetic field is indicated.

Physics of Magnetism and Magnetic Materials

2003-01-01

K.H.J. Buschow , F.R. de Boer

Classics in Magnetics A Phenomenological Theory of Damping in Ferromagnetic Materials

2004-11-01

T. L. Gilbert

In 1955, a phenomenological theory of ferromagnetism was well established and had been corroborated by a considerable amount of experimental data. However, there were problems in the phenomenological theory of … In 1955, a phenomenological theory of ferromagnetism was well established and had been corroborated by a considerable amount of experimental data. However, there were problems in the phenomenological theory of the dynamics of the magnetization field. The Landau-Lifshitz equation for damping of the motion of the magnetization field could not account for the large noneddy-current damping in thin Permalloy sheets. The problem undertaken herein is a reformulation of the theory in a way that is more consistent with the theory of damping in other physical systems in order to be able to take large damping into account.

Adaptive control of plants with unknown hystereses

1995-01-01

Gang Tao , P.V. Kokotović

For a system with hysteresis, the authors present a parameterized hysteresis model and develop a hysteresis inverse. The authors then design adaptive controllers with an adaptive hysteresis inverse for plants … For a system with hysteresis, the authors present a parameterized hysteresis model and develop a hysteresis inverse. The authors then design adaptive controllers with an adaptive hysteresis inverse for plants with unknown hysteresis. A new adaptive controller structure is introduced which is capable of achieving a linear parameterization and a linear error model in the presence of a hysteresis nonlinearity. A robust adaptive law is used to update the controller parameters and hysteresis inverse parameters, which ensures the global boundedness of the closed-loop signals for a wide class of of hysteresis models. Simulations show that the use of the adaptive hysteresis inverse leads to major improvements of system performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

A Theory of Metallic Ferro- and Antiferromagnetism on Zener's Model

1956-07-01

T. Kasuya

The importance to the mechanism of ferromagnetism of exchange interaction between conduction electrons and unfilled inner shell electrons (called s-d interaction) has been pointed out by Zener. Especially for rare … The importance to the mechanism of ferromagnetism of exchange interaction between conduction electrons and unfilled inner shell electrons (called s-d interaction) has been pointed out by Zener. Especially for rare earth metals, this interaction seems to be the only mechanism which can cause ferro- and antiferromagnetism. However Zener's works are unsatisfactory because his model is phenomenological and moreover does not involve antiferromagnetism and spin wave mode. Our paper considers this s-d interaction on a more rigorous basis. By a certain approximation, there appear long range exchange type interactions between d-electron spins and, in certain conditions both ferro- and antiferromagnetism appear. The excitations of spin wave modes are the same as those in the ordinary modes of the short range exchange force, viz, the energy of the spin wave excitations is proportional to q2 for ferromagnetism and q for antiferromagnetism in the region of small wave vector q. The T3/2 law for the temperature dependence of the magnetization of ferromagnetism is applicable up to very high temperatures, and this result is in good agreement with the results of experiments on metallic ferromagnetism.

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The present status of the temperature dependence of magnetocrystalline anisotropy, and the power law

1966-08-01

Herbert B. Callen , Earl Callen

A mechanism of magnetic hysteresis in heterogeneous alloys

1991-07-01

Edmund C. Stoner , E.P. Wohlfarth

It is suggested that in many ferromagnetic materials there may occur particles distinct in magnetic character from the general matrix, and below the critical size, depending on shape, for which … It is suggested that in many ferromagnetic materials there may occur particles distinct in magnetic character from the general matrix, and below the critical size, depending on shape, for which domain boundary formation is energetically possible. For such single-domain particles, change of magnetization can take place only by rotation of the magnetization vector. As the field changes continuously, the resolved magnetization may change discontinuously at critical values of the field. The character of the magnetization curves depends on the degree of magnetic anisotropy of the particle and on the orientation of easy axes with respect to the field. The magnetic anisotropy may arise from the shape of the particle, from magnetocrystalline effects, and from strain. A detailed quantitative treatment is given of the effect of shape anisotropy when the particles have the form of ellipsoids of revolution, along with a less detailed treatment for the general ellipsoidal form.

Application of Zinc Oxide Varistors

1990-07-01

Tapan K. Gupta

This paper deals with the application of ZnO varistors—an area which has not been treated in a systematic way in the literature. The paper starts with a brief description of … This paper deals with the application of ZnO varistors—an area which has not been treated in a systematic way in the literature. The paper starts with a brief description of the fundamental properties comprising the electrical behavior as well as the physics, chemistry, and microstructure of the varistor. These properties then form the basis for defining the application parameters that are directly related to the nonlinear current‐voltage characteristics of the varistor. This paper provides a detailed description of these parameters and their relation to microstructure and the processing of the varistor. Finally, a discussion is presented on the reliability of the varistor by considering a grain‐boundary defect model which explains both the instability and the stability under use conditions.

On the Curie points and high temperature susceptibilities of Heisenberg model ferromagnetics

1958-07-01

G. S. Rushbrooke , P.J. Wood

The first six coefficients in the expansion of the susceptibility χ, and its inverse, χ −1, in ascending powers of the reciprocal temperature, have been determined for the Heisenberg model … The first six coefficients in the expansion of the susceptibility χ, and its inverse, χ −1, in ascending powers of the reciprocal temperature, have been determined for the Heisenberg model of a ferromagnetic, for any spin value, S, and any lattice. The first five coefficients appropriate to the magnetic specific heat, C, have also been found. For the body-centred and face-centred cubic lattices, the χ and C coefficients are tabulated for half-integral S from 1/2 to 3. From these coefficients estimates have been made of the reduced Curie temperatures, θs c= k T c/J. It is found that for the simple, body-centred and face-centred cubic lattices the formula reproduces the estimated Curie temperatures fairly accurately. Here X=S(S+1) and z is the lattice coordination-number. It is found that, suitably scaled, the theoretical curves for inverse susceptibility against temperature above the Curie point are rather insensitive to the spin value and to the precise lattice structure. The ratio of their initial to their final gradients is approximately 0·3. A comparison is made with the experimental values of χ −1 for both iron and nickel. If iron is represented by the Heisenberg model with S=1, then the observed Curie temperature corresponds to a J value of 1·19×10−2 ev. Brief consideration is given to the use of the tabulated coefficients for antiferromagnetic problems.

Effects of eddy currents in transformer windings

1966-01-01

P.L. Dowell

The effects of eddy currents in transformer windings are considered, and a method is derived for calculating the variation of winding resistance and leakage inductance with frequency for transformers with … The effects of eddy currents in transformer windings are considered, and a method is derived for calculating the variation of winding resistance and leakage inductance with frequency for transformers with single-layer, multilayer and sectionalised windings. The method consists in dividing the winding into portions, calculating the d.c. resistances and d.c. leakage inductances of each of these portions, and then multiplying the d.c. values by appropriate factors to obtain the corresponding a.c. values. These a.c. values are then referred to, say, the primary winding and summed to give the total winding resistance and leakage inductance of the transformer. Formulas are derived and quoted for calculating the d.c. resistances and leakage inductances of the winding portions. Theoretical expressions are derived for the variation with frequency etc. of the factors by which the d.c. values must be multiplied to obtain the corresponding a.c. values. These expressions are presented in the form of graphs, permitting the factors to be read as required.

Magnetostrictive properties of body-centered cubic Fe-Ga and Fe-Ga-Al alloys

2000-01-01

A. E. Clark , J. B. Restorff , M. Wun‐Fogle +2 more

The magnetic and magnetostrictive properties of Fe/sub 1-x/Ga/sub x/ and Fe/sub 1-x-y/Ga/sub x/Al/sub y/ (a+y<0.3) single crystals were measured under compressive stresses up to 120 MPa and in magnetic fields … The magnetic and magnetostrictive properties of Fe/sub 1-x/Ga/sub x/ and Fe/sub 1-x-y/Ga/sub x/Al/sub y/ (a+y<0.3) single crystals were measured under compressive stresses up to 120 MPa and in magnetic fields up to 1 kOe. Values of /spl lambda//sub 100/ exceeding 200 ppm were observed in samples of Fe/sub 83/Ga/sub 17/ from 180 K to room temperature. Only a small monotonic decrease in magnetostriction with temperature was found. On the other hand, /spl lambda//sub 111/ maintained small negative values close to those of b.c.c. Fe. In all cases, no higher order magnetostrictive terms were detectable. With 15 to 20 atomic percent replacement of Fe by Ga, the magnetizations remain high (M, /spl cong/1.8 T) and the magnetic anisotropies reduced (K/sub 1//spl cong/10/sup 4/ J/m/sup 3/). Values of the 'stiff' (high magnetic field) Young's modulus, Bulk modulus, Poison's ratio, and elastic constant C/sub 11/-C/sub 12/ for Fe/sub 85/Ga/sub 15/ at room temperature are, respectively, 77 GPa, 111 GPa, 0.38, and 56 GPa.

Magnetostriction of martensite

1998-05-01

Richard D. James , Manfred Wuttig

Abstract A general strategy is described for inducing magnetostriction in ferromagnetic martensitic materials. An analysis of domain redistribution caused by a magnetic field is given, and certain relations between material … Abstract A general strategy is described for inducing magnetostriction in ferromagnetic martensitic materials. An analysis of domain redistribution caused by a magnetic field is given, and certain relations between material constants that promote this effect are described. These relations suggest a ‘constrained theory of magnetostriction’ which is used to predict strain against field in a tetragonal martensite subject to an orthogonal biaxial magnetic field and uniaxial stress. These predictions are compared with the corresponding experiments in Fe70Pd30. Reversible field-induced strains of 0.6% are exhibited in this system. Microstructural observations confirm that these strains are caused by a field-induced redistribution of martensitic twins.

On the theory of the dispersion of magnetic permeability in ferromagnetic bodies

1992-01-01

Luiz Landau , Efrat Lifshitz

A Lagrangian Formulation of the Gyromagnetic Equation of the Magnetization Field

1955-01-01

T. L. Gilbert

On the Theory of Ferromagnetic Resonance Absorption

1948-01-01

C. Kittel

Introduction to the Theory of Ferromagnetism

2001-01-04

Amikam Aharoni

Abstract The present book is the second edition of Amikam Aharoni's Introduction to the Theory of Ferromagnetism, based on a popular lecture course. Like its predecessor, it serves a two-fold … Abstract The present book is the second edition of Amikam Aharoni's Introduction to the Theory of Ferromagnetism, based on a popular lecture course. Like its predecessor, it serves a two-fold purpose: First, it is a textbook for first-year graduate and advanced undergraduate students in both physics and engineering. Second, it explains the basic theoretical principles on which the work is based for practising engineers and experimental physicists who work in the field of magnetism, thus also serving to a certain extent as a reference book. For both professionals and students the emphasis is on introducing the foundations of the different subfields, highlighting the direction and tendency of the most recent research. For this new edition, the author has thoroughly updated the material especially of chapters 9 ('The Nucleation Problem') and 11 ('Numerical Micromagnetics'), which now contain the state of the art required by students and professionals who work on advanced topics of ferromagnetism. From reviews on the 1/e: '... a much needed, thorough introduction and guide to the literature. It is full of wisdom and commentary. Even more, it is Amikam Aharoni at his best - telling a story... He is fun to read... The extensive references provide an advanced review of micromagnetics and supply sources for suitable exercises... there is much for the student to do with the guidance provided by Introduction to the Theory of Ferromagnetism.' A. Arrott, Physics Today, September 1997

Mathematical models of hysteresis and their applications

2003-01-01

I.D. Mayergoyz

[Mathematical models of hysteresis]

1991-01-01

I.D. Mayergoyz

The research described in this proposal is currently being supported by the US Department of Energy under the contract Mathematical Models of Hysteresis''. Thus, before discussing the proposed research in … The research described in this proposal is currently being supported by the US Department of Energy under the contract Mathematical Models of Hysteresis''. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories''. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

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Introduction to Magnetism and Magnetic Materials

1991-01-01

David Jiles

The Hall Effect in Metals and Alloys

1972-01-01

C. M. Hurd

Systems with Hysteresis

1989-01-01

M. A. Krasnosel’skii , Aleksei V. Pokrovskiǐ

Magnetism and metallurgy

1969-01-01

A. E. Berkowitz , Eckart Kneller

Effect of resin types on magnetic properties and mechanical strength of FeSiBC amorphous magnetic powder cores

2025-06-20

Zhengqu Zhu , Pu Wang , Jing Pang +1 more | Journal of Iron and Steel Research International

Equivalent Modeling of Temperature Field for Amorphous Alloy 3D Wound Core Transformer for New Energy

2025-06-19

Jianwei Han , Xiaolin Hou , Xinglong Yao +6 more | Energies

It is of the utmost importance to accurately solve the transformer temperature field, as it governs the overall performance and operational stability of the transformer. However, the intricate structure of … It is of the utmost importance to accurately solve the transformer temperature field, as it governs the overall performance and operational stability of the transformer. However, the intricate structure of high- and low-voltage windings, insulating materials, and other components presents numerous challenges for modeling. Temperature exerts a significant influence on insulation aging, and elevated temperatures can notably accelerate the degradation process of insulation materials, reducing their service life and increasing the risk of electrical failures. In view of this, this paper proposes an equivalent modeling method of the temperature field of the transformer HLV winding and studies the refined modeling of the winding part. First of all, in order to reduce the difficulty of temperature field modeling, based on the principle of constant thermal resistance, the fine high- and low-voltage windings are equivalent to large conductors, and the equivalent thermal conductivity coefficient of the high- and low-voltage windings is obtained, which improves the calculation accuracy and shortens the calculation time. Secondly, we verify the feasibility of the equivalent model before and after the simulation, analyze the influence of different boundary conditions on the winding temperature field distribution, and predict the local hotspot location and temperature trend. Finally, a 50 kVA amorphous alloy winding-core transformer is tested on different prototypes to verify the effectiveness of the proposed method.

An Iterative Error Correction Procedure for Single Sheet Testers Using FEM 3D Model

2025-06-18

Robert Krobot , Martin Dadić | Sensors

Determination of single-valued BH curve and power loss curve of electric steels is an important parameter in the design of electrical machines and transformers. This paper proposes a correction procedure … Determination of single-valued BH curve and power loss curve of electric steels is an important parameter in the design of electrical machines and transformers. This paper proposes a correction procedure for the measurement of anhysteretic BH curve and power losses, based on the finite element model (FEM) and SST apparatus. A 3D finite element model (FEM) of the SST (Single Sheet Tester) was developed with respect to the IEC 60404-3 standard. The measurement results obtained with a standardized SST apparatus are fed to its FEM and used to iteratively correct initial BH and power loss curves, obtained using magnetic equivalent circuits theory. The proposed iterative correction procedure is based on the steepest descent algorithm, while the stopping criteria were based on the difference between simulated and measured global variables (power loss, induced voltage, and primary current). After correction, root mean squared errors were decreased from 1.85 A/m to 42.88 × 10-3 A/m for the BH curve, and from 44.5 × 10-4 W/kg to 7.28 × 10-4 W/kg for the power loss curve.

Design and optimization of a new axial flux permanent magnet hysteresis motor with simple structure

2025-06-18

Hashem Yousefi Javid , Aydin Yousefi Javid | COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

Purpose This paper aims to proposes a new topology of axial flux permanent magnet hysteresis motor with a single-disc rotor. Design/methodology/approach In this paper, first, the main equations of the … Purpose This paper aims to proposes a new topology of axial flux permanent magnet hysteresis motor with a single-disc rotor. Design/methodology/approach In this paper, first, the main equations of the permanent magnet hysteresis motor with a single-disc rotor design are presented. Then, the permanent magnet hysteresis motor with single-disc rotor has been precisely simulated by finite element method using the Preisach model (for modeling semi-hard material). Subsequently, the diameters of the permanent magnet and semi-hard material have been optimized by sensitivity analysis in finite element method. Findings By adding a ring magnet to axial flux hysteresis (semi-hard magnetic material) motor, ability to increase torque in steady state is provided. In the starting state, the semi-hard material produces torque while in the steady state, the torque is produced by both the semi-hard material and the permanent magnet. The results show that due to the proper combination of the permanent magnet and semi-hard material, and choosing optimum diameters for them, the resultant torque is desirably high for both steady and starting states. Originality/value The authors hereby attest that the research paper they have submitted is the result of their own independent and unique labor. All of the sources from which the thoughts and passages were derived have been properly credited. The work has not been submitted for publication anywhere and is devoid of any instances of plagiarism.

Instability in domain wall dynamics in almost compensated ferrimagnets

2025-06-17

NULL AUTHOR_ID | Physical review. B./Physical review. B

Current drive magnetic domain wall motion in heterostructure films

2025-06-16

Rui Fu , Jiwen Chen , Zhigao Huang +3 more | Chinese Physics B

Abstract With the rise of big data, the increasing volume of information has raised significant demands on data storage technologies, presenting various challenges to current information storage solutions. Consequently, finding … Abstract With the rise of big data, the increasing volume of information has raised significant demands on data storage technologies, presenting various challenges to current information storage solutions. Consequently, finding more efficient and higher-capacity methods for data storage has become crucial. In comparison to conventional semiconductor random access memory, magnetic random access memory (MRAM), which has been progressively developed in recent years, shows promise as a candidate for the next generation of information storage due to its notable advantages, including non-volatility, high density, stability, low power consumption, and resistance to radiation. Among the MRAM variants, Spin-Orbit Torque Magnetic Random Access Memory (SOT-MRAM) exhibits considerable potential for advancement. Utilizing a vertical magnetized thin film structure made up of heavy metal and ferromagnetic metal, SOT-MRAM leverages the strong spin-orbit coupling effect of the heavy metal to convert the flow of charge into pure spin flow. This process also allows for the injection of spin accumulation from the interface into the adjacent magnetic layer through mechanisms such as the spin Hall effect and the Rashba effect, ultimately applying spin-orbit torque to manipulate the magnetic moment of the magnetic layer, facilitating its reversal.<break/>This paper primarily investigates the physical mechanisms underlying the motion of magnetic domain walls driven by current-induced spin-orbit moments in vertically magnetized heterostructures. Utilizing a magneto-optical Kerr microscope to observe the movement of the magnetic domain walls, the study analyzes and compares the velocity behaviors of the domain walls across different cobalt thicknesses. These investigations offer valuable design insights for applications involving track memory driven by spin-orbit moments.

Replacing Backpropagation with the Forward-Forward (FF) Algorithm in Transformer Models

2025-06-16

Hyun Jung Kim , S. Yoo | Tehnički glasnik

This study proposes a novel integration of the Forward-Forward (FF) algorithm into Transformer architectures as an efficient and gradient-free alternative to Backpropagation (BP). Motivated by the computational limitations of BP-such … This study proposes a novel integration of the Forward-Forward (FF) algorithm into Transformer architectures as an efficient and gradient-free alternative to Backpropagation (BP). Motivated by the computational limitations of BP-such as high memory usage and gradient instability-we aim to examine whether FF can maintain comparable model performance while improving training efficiency. We present both theoretical justifications and empirical evaluations on the IMDB sentiment analysis dataset. Our experiments show that FF reduces training time by approximately 20% and memory usage by 30%, with only a marginal decrease in BLEU score (27.8 vs. 28.3) and slight increase in Perplexity (13.2 vs. 12.5). Furthermore, we extend our evaluation across varying model depths and hardware platforms (desktop GPU, cloud GPU, SoC-based laptop), and perform statistical testing and ablation studies to investigate FF’s behavior within Transformer components. These results highlight the viability of FF for scalable, rethereforeurce-efficient Transformer training and provide a foundation for future research in hybrid and distributed deep learning frameworks.

Magnetism in iron alloys: methodological advances for thermodynamics, defects, and kinetics

2025-06-14

Tilmann Hickel , Sergiy V. Divinski , Sergey Starikov +7 more | International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde)

Abstract Steels are among the technologically and economically most relevant materials. Key innovations in important sectors of human society such as mobility, energy and safety, are currently based on alloying … Abstract Steels are among the technologically and economically most relevant materials. Key innovations in important sectors of human society such as mobility, energy and safety, are currently based on alloying of Fe with other transition-metal elements such as Mn, Cr, or Co. Due to strong impacts and conceptual challenges related to magnetism, however, the fundamental understanding and the ability to computationally design these steels in high-throughput approaches lags behind other classes of alloys. In this article, we will provide a substantial review of the role of magnetism, magnetic excitations and transformations for alloy thermodynamics, point defects, interfaces and kinetics. This will be achieved by combining insights from different methods: Ab initio simulations have the advantage that the magnetic ground state is intrinsic part of the electronic minimization. Due to the coarsening of the many-electron structures and therewith magnetic interactions, tight-binding methods can handle larger system sizes. Effective interaction models provide the freedom to exploit more sophisticated magnetic interactions. The performance of these methods in terms of magnetic properties of Fe alloys will be evaluated by providing state-of-the-art results for their sensitivity to magnetism. Furthermore, dedicated experiments will be discussed to complete the understanding of magnetic effects in Fe alloys and to validate the modeling strategy.

Anomalous excess loss in soft magnetic composites

2025-06-14

Du‐Xing Chen | The European Physical Journal Plus

Effect of Casting Temperature and Atmosphere on Deposited Film, Interfacial Heat Transfer and Solidification Structure of 3.5 Wt Pct Silicon Steel Under Sub-rapid Solidified Process

2025-06-13

Jingzhou Lu , Yunli Zhang , Lulu Song +2 more | Metallurgical and Materials Transactions B

Anomalous Hall effect in highly c-plane oriented Mn$_{3}$Ge/Si(100) thin films grown by pulsed laser deposition

2025-06-12

Indrajit Sinha , P Dutta , Nazma Firdosh +3 more | Journal of Physics Condensed Matter

Abstract Antiferromagnetic Mn$_{3}$Ge with a non-collinear Kagome structures present exciting prospects for exploring Berry curvature driven anomalous Hall effects (AHE). &#xD; Despite substantial progress in bulk systems, the synthesis of … Abstract Antiferromagnetic Mn$_{3}$Ge with a non-collinear Kagome structures present exciting prospects for exploring Berry curvature driven anomalous Hall effects (AHE). &#xD; Despite substantial progress in bulk systems, the synthesis of crystalline thin films directly on silicon with a hexagonal phase presents a particular challenge unless a buffer layer is employed.&#xD; In this study, we report the synthesis of single phase c-plane oriented hexagonal Mn$_{3}$Ge(0001) films on Si(100) using pulsed laser deposition. Under suitable growth conditions, we obtain layer-by-layer films with atomically flat surfaces and interfaces. High-resolution scanning tunneling microscopy study reveals the detail surface atomic structures, where the surface Mn atoms spontaneously arrange into a Kagome lattice. Tunneling spectroscopy (dI/dV) measurement on the atomically resolved Kagome surface show a minima in local density of states near the Fermi level, likely originated from the Weyl crossings near K points. Despite the nearly vanishing magnetization, magnetotransport measurements in 30 nm $Mn_{3}$Ge(0001) films show anomalous Hall resistivity up to 0.41 ($\mu\Omega\cdot\text{cm}$) at 2 K. &#xD;Our \textit{ab initio} calculations shed further light on the existence of topological features and the band structures in Mn$_{3+x}$Ge$_{1-x}$ with increasing Mn concentration $x$. The anomalous Hall response at room temperature in crystalline Mn$_{3}$Ge films on Si(100) offer promising potential for the development of antiferromagnetic spintronics.&#xD;

The DOS Functions in HD Non-Parabolic Materials Under Magneto-Size Quantization and the RLC

2025-06-08

A fully coupled modular finite element framework for investigating the impact of myocardial contraction on magnetocardiography magnetic field maps

2025-06-06

Chen Yang , Yuelong Cao , Min Xiang | Journal of Physics D Applied Physics

Abstract More accurate mechanistic modeling of magnetocardiography (MCG) is crucial for clinically guiding medical professionals in diagnosing heart diseases. The bioelectric current in the heart generates an electromagnetic field on … Abstract More accurate mechanistic modeling of magnetocardiography (MCG) is crucial for clinically guiding medical professionals in diagnosing heart diseases. The bioelectric current in the heart generates an electromagnetic field on the body surface. Although previous studies have highlighted the role of myocardial electromechanical feedback in electrophysiological output, its impact on magnetic fields remains underexplored. In this work, we first explore the effect of myocardial contraction on magnetic field maps (MFM) by proposing a fully coupled modular finite element framework. The solution of myocardial transmembrane potentials is primarily derived by considering the ion current activated by excitation in the static ventricle and the ion current induced by stretching during myocardial contraction. After defining the myocardial fiber orientation, the active stress, which varies with the transmembrane potentials, is decomposed additively along the fiber direction to simulate ventricular mechanical contraction. The transmembrane potentials are then used to calculate the impressed current density in the heart, and the volume conduction problem is solved via current conservation to determine the total current density in the torso. This total current density is subsequently used to solve the quasi-static magnetic problem. The accuracy of the calculation framework was assessed both qualitatively and quantitatively by comparing MFM under static ventricular and myocardial contraction conditions.&#xD;

Quasispins of vacancy defects and their interactions in disordered antiferromagnets

2025-06-06

NULL AUTHOR_ID | Physical review. B./Physical review. B

Influence of online-heat preservation of cast strip on microstructure and magnetic properties of 4.5wt%Si non-oriented electrical steel in strip casting

2025-06-02

Guoqing Zu , Shuyu Zhou , Yukuan Lu +6 more | Materials Science and Technology

The twin-roll strip casting 4.5wt.% silicon steel with equiaxed crystal structure was subjected to online-heat preservation treatment at 1323 K for different times to adjust the various structures of the … The twin-roll strip casting 4.5wt.% silicon steel with equiaxed crystal structure was subjected to online-heat preservation treatment at 1323 K for different times to adjust the various structures of the cast strip. By comprehensively analyzing its cold-rolled microstructure, recrystallization and texture evolution, the formation of recrystallized texture and its impact on magnetic properties were determined. Through process optimization, the iron loss is reduced by 1.97 W/kg after 60 min of online heat preservation. This study provides an effective method for optimizing microstructure and texture of the as cast strip, and proves that appropriate online-heat preservation of cast strips is beneficial to the improvement of the magnetic properties of 4.5wt.% Si electrical steel.

Enhanced magnetoelastic stress in disordered iron-gallium alloy thin films revealed by direct measurement

2025-06-01

Adrián Begué , Maria Grazia Proietti , J. I. Arnaudas +1 more | Journal of Alloys and Compounds

Toroid, altermagnetic and noncentrosymmetric ordering in metals

2025-06-01

V. P. Mineev | Physics-Uspekhi

Toroid, altermagnetic and noncentrosymmetric ordering in metals

2025-06-01

V. P. Mineev | Uspekhi Fizicheskih Nauk

Effects of Y and Hf addition on soft magnetic property and ductility improvement of Fe–6.9 wt% Si alloy

2025-06-01

Guojun Cai , Yanru Huang , Yongquan Qing +1 more | Journal of Materials Research and Technology

Physics aware machine learning for micromagnetic energy minimization: recent algorithmic developments

2025-06-01

Sebastian Schaffer , T. Schrefl , Harald Oezelt +2 more | Computer Physics Communications

Voltage-controlled motion of transverse domain walls in cubic magnetostrictive materials under transverse magnetic field

2025-06-01

Sumit Maity , Ambalika Halder , Sharad Dwivedi | Journal of Magnetism and Magnetic Materials

Quantitative Evaluation of Flexible Mutual Aid Matching Metrics for Low voltage transformer area

2025-06-01

Dan Zhu , Min Li , Hanlin Zhang +2 more | Journal of Physics Conference Series

Abstract In order to solve the problems of load imbalance or seasonal load fluctuation between stations, distribution substation overload caused by electric vehicle load, power supply failure that cannot be … Abstract In order to solve the problems of load imbalance or seasonal load fluctuation between stations, distribution substation overload caused by electric vehicle load, power supply failure that cannot be load transferred in time, reverse overload and power quality caused by a high proportion of distributed PV accessed to the station area, and so on. Taking Suzhou as an example, based on the OLP model system, we sort out the problem labels of Suzhou station areas and establish a corresponding judging system, calculate the residual shortage of station areas by comparing the differences in the labels of the sample station areas, and screen out the stations suitable for carrying out flexible interconnection, connecting adjacent stations flexibly, realizing the power inter-calculation between the station areas and supporting the coordinated and optimized operation of low-voltage stations, so as to provide basis for the precise selection of the point of the coordinated control of the flexible and direct low-voltage stations.

Lightweight main drive motor of electric aircraft based on amorphous alloy material and thermal-solid coupling optimization

2025-06-01

Jingchao Zhou , Ping Chen , Qiuming Gong +3 more | Journal of Physics Conference Series

Abstract To solve the problems of excessive weight, insufficient power density, and energy efficiency of the main drive motor in electric aircraft, and based on thermo-solid coupling theory and electromagnetic … Abstract To solve the problems of excessive weight, insufficient power density, and energy efficiency of the main drive motor in electric aircraft, and based on thermo-solid coupling theory and electromagnetic field optimization theory, amorphous alloy material and topology optimization technology are adopted, combined with multi-physical field simulation software such as Maxwell, FLUENT and ANSYS, to ensure that the mechanical strength and temperature rise distribution of motor meet the requirements. The lightweight target of 8.12% weight reduction of motor stator core and 28.1% weight reduction of rotor core is realized, which significantly improves the power density and energy efficiency of the main drive motor of electric aircraft.

Evaluation Technology of Thermal Demagnetization in IPMSM for Automotive Traction Drives

2025-05-31

J. Hinata , Yusuke Sugiyama , Yoshiaki Kano +1 more | IEEJ Transactions on Industry Applications

Magnetic Properties of Fe-(Ga,Ge) Compounds: Insights from Ab initio and Monte Carlo Simulations

2025-05-30

O. O. Pavlukhina , M. V. Matyunina , М. А. Загребин +3 more | Journal of Superconductivity and Novel Magnetism

Image of helical local moment magnetic order in the STM spectrum

2025-05-29

NULL AUTHOR_ID | Physical review. B./Physical review. B

The Need to Investigate the Behaviour of Reinforcement using a Metal Magnetic Memory

2025-05-28

Noorsuhada Md Nor , Nur Atikah Adila Abdul Mutalib , Azli Arifin +1 more | Jurnal Kejuruteraan

The occurrence of damage in reinforced concrete (RC) beams is influenced by various factors such as the material properties. The localisation of invisible damage and the identification of the critical … The occurrence of damage in reinforced concrete (RC) beams is influenced by various factors such as the material properties. The localisation of invisible damage and the identification of the critical stress state leading to structural damage or failure of the steel bars are crucial tasks in structural diagnosis. Hence, the main objective of this study is to investigate the behaviour of steel bars using magnetic metal memory (MMM) before any significant stress or load has been applied. Two types of reinforcement were prepared, differing in the tensile part. Steel bars with a size of 12 mm and 16 mm were used for the tensile part. A total of six reinforcements were prepared for each size of steel bars. The MMM was used to scan the behaviour of the steel bars in the tensile section along the scan line of 1150 mm. From the MMM test, two magnetic flux leakage signals were analysed: Component signals, Hp-2 and normal gradient signals, dH(y)/dx. It was found that the larger variations observed in the 16 mm steel bar could indicate a greater susceptibility to defects or stress concentrations in the material. The differences in the signal patterns between the two diameters could also reflect the response of the material. This study is of significant benefit as a baseline measurement to understand the initial condition of the steel and to better monitor and evaluate its performance throughout the life cycle of the reinforced concrete structure.

Comparative Investigation on Microstructure, Texture, and Properties of Copper-Bearing and Copper-Free Non-oriented Electrical Steels

2025-05-28

Yufan Wang , Guoqing Zu , Mingyu Li +5 more

Time-domain equations for modeling partially-magnetized ferrite

2025-05-27

Abdelwahab Benouattas

Theoretical framework predicts magnetoelastic effect in soft systems

2025-05-27

Kendra Redmond

The Dual Influence of Silicon Content and Mechanical Stress on Magnetic Barkhausen Noise in Non-Oriented Electrical Steel

2025-05-27

Aroba Saleem , Mehdi Mehdi , P. R. Underhill +2 more | Metals

Magnetic Barkhausen noise (MBN) analysis is a non-destructive evaluation technique that offers significant advantages in assessing the magnetic properties of electrical steels. It is particularly useful for quality control in … Magnetic Barkhausen noise (MBN) analysis is a non-destructive evaluation technique that offers significant advantages in assessing the magnetic properties of electrical steels. It is particularly useful for quality control in electrical steel production and for evaluating magnetic quality during core manufacturing and assembly. Despite its potential, MBN has not been widely used in electrical steel characterization. One obstacle is that the effects of silicon content in the electrical steel and the residual stress generated during its processing on MBN have not been thoroughly understood, limiting the practical application of the MBN technique in the electrical steel and electric motor industries. To address this knowledge gap, this paper investigates the MBN responses from four non-oriented electrical steel (NOES) sheets with varying silicon contents (0.88, 1.8, 2.8, and 3.2 wt%) but similar other elements. The measurements were performed both with and without applied tensile stress. It is observed that increasing the Si content increases the pinning density, which, together with the microstructure and texture, largely impacts the MBN response. In addition, the MBN energy increases with the applied stress, which can be attributed to the increase in the number of 180° domain walls (DWs) in the direction of stress. The rate of this MBN increase, however, differs among steels with different silicon concentrations. This difference is due to the combined effect of the DWs and pinning density. When the DW spacing becomes less than the jump distance between the pinning sites, no further increase in the MBN energy is observed with additional stress. The reported results provide a basis for the interpretation of MBN signals for varying wt% Si in NOES when residual stresses are present.

High-throughput computation and machine learning modeling of magnetic moments and Mössbauer parameters for Fe-based intermetallics

2025-05-27

NULL AUTHOR_ID