Magnetic Hysteresis In Novel Magnetic Materials

A detailed presentation of the physics of the various hysteresis models that are currently used to explain the magnetization reversal process, including coherent and incoherent magnetization processes, micromagnetism and its application in thin films, multilayers, nanowires, particles and bulk magnets, domain wall pinning and domain wall dynamics, and Preisach modelling. Some of the faulty concepts and interpretations that still exist in the literature are rectified. Magnetic imaging techniques are reviewed, including TEM, SEM, magnetic force microscopy, and optical microscopy. Temperature, field and angular dependence of coercivity, magnetic interactions and magnetic phenomena are reviewed and their effect on magnetic hysteresis is discussed. The magnetic properties of novel materials are discussed, including nanoparticles, nanocrystalline granular solids, particulate media, thin films, and bulk magnets. Finally, present and future applications of novel materials are presented, including magnetic and magneto-optic recording media, magneto-electronics, sensors, magnetic circuit design, and novel structures created from rigid, high-energy permanent magnets.

This book provides a comprehensive treatment of the physics of hysteresis in magnetism and of the mathematical tools used to describe it. Hysteresis in Magnetism discusses from a unified viewpoint the relationsof hysteresis to Maxwells equations, equilibrium and non-equilibrium thermodynamics, non-linear system dynamics, micromagnetics, and domain theory. These aspects are then applied to the interpretation of magnetization reversal mechanisms: coherent rotation and switching in magnetic particles, stochastic domain wall motion and the Barkhausen effect, coercivity mechanisms and magnetic viscosity, rate-dependent hysteresis and eddy-current losses. The book emphasizes the connection between basic physical ideas and phenomenological models of interest to applications, and, in particular, to the conceptual path going from Maxwells equations and thermodynamics to micromagnetics and to Preisach hysteresis modeling. The reader will get insight into the importance and role of hysteresis in magnetism; In particular, he will learn: which are the fingerprints of hysteresis in magnetism which are the situations in which hysteresis may appear how to describe mathematically these situations how to apply these descriptions to magnetic materials how to interpret and predict magnetic hysteresis phenomena observed experimentally

Understanding magnetic hysteresis is vitally important to the development of the science of magnetism as a whole and to the advancement of practical magnetic device applications. Magnetic Hysteresis, by acclaimed expert Edward Della Torre, presents a clear explanation of the connection between physical principles and phenomenological hysteresis. This comprehensive book offers a lucid analysis that enables the reader to save valuable time by reducing trial-and-error design. Dr. Della Torre uses physical principles to modify Preisach modeling and to describe the complex behavior of magnetic media. While Pretsach modeling is a useful mathematical tool, its congruency and deletion properties present limitations to accurate descriptions of magnetic materials. Step-by-step, this book describes the modifications that can overcome these limitations. Special attention is given to the use of feedback around a Preisach transducer to remove the congruency restriction, and to the use of accommodation and aftereffect models to remove the deletion restriction. Magnetic state selection rules are introduced to couple scalar Preisach models to form a vector model. Magnetic Hysteresis is indispensable reading for engineers, physicists, and materials scientists who want to gain a better understanding of hysteresis losses and create more energy-efficient motor designs.

Introduction: Magnetic Hysteresis. Types of Hysteresis. Maxwells Equations and Thermodynamics: Maxwells Equations in Magnetic Media. Magnetic Work and Thermodynamics. Magnetic Free Energy: Exchange and Anisotropy. Micromagnetics. Magnetic Domains and Domain Walls. The Magnetization Process: Coherent Rotation. Domain Wall Motion. Magnetization Curves. Coercivity Mechanisms. Eddy Currents. Preisach Systems: Collections of Bistable Units. Hysteresis in Preisach Systems. Appendixes: Systems of Units. Vector Relations. Reciprocity Theorems. Micromagnetic Parameters. Stochastic Processes. Bibliography. Index.

Few subjects in science are more difficult to understand than magnetism, according to Encyclopedia Britannica. However, there is a strong demand today for scientists and engineers with skills in magnetism because of the growing number of technological applications utilizing this phenomenon. This textbook responds to the need for a comprehensive introduction of the basic concepts of the science. Introduction to Magnetism and Magnetic Materials has been thoroughly revised since the first edition to include recent developments in the field. The early chapters comprise a discussion of the fundamentals of magnetism. These chapters include more than 60 sample problems with complete solutions to reinforce learning. The later chapters review the most significant recent developments in four important areas of magnetism: hard and soft magnetic materials, magnetic recording, and magnetic evaluation of materials. These later chapters also provide a survey of the most important areas of magnetic materials for practical applications. Extensive references to the principal publications in magnetism are listed at the end of each chapter, which offer the reader rapid access to more specialized literature. Students in various scientific areas will benefit from this book, including those in physics, materials science, metallurgy, and electrical engineering.

In this book, the fundamentals of magnetism are treated, starting at an introductory level. The origin of magnetic moments, the response to an applied magnetic field, and the various interactions giving rise to different types of magnetic ordering in solids are presented and many examples are given. Crystalline-electric-field effects are treated at a level that is sufficient to provide the basic knowledge necessary in understanding the properties of materials in which these effects play a role. Itinerant-electron magnetism is presented on a similar basis. Particular attention has been given to magnetocrystalline magnetic anisotropy and the magnetocaloric effect. Also, the usual techniques for magnetic measurements are presented. About half of the book is devoted to magnetic materials and the properties that make them suitable for numerous applications. The state of the art is presented of permanent magnets, high-density recording materials, soft-magnetic materials, Invar alloys and magnetostrictive materials. Many references are given.

Magnetic Materials and their Applications discusses the principles and concepts behind magnetic materials and explains their applications in the fields of physics and engineering. The book covers topics such as the principal concepts and definitions related to magnetism; types of magnetic materials and their electrical and mechanical properties; and the different factors influencing magnetic behavior. The book also covers topics such as permanent-magnet materials; magnetic materials in heavy-current engineering; and the different uses of magnetic materials. The text is recommended for physicists and electrical engineers who would like to know more about magnetic materials and their applications in the field of electronics.

Introduction to Magnetic Materials, 2nd Edition covers the basics of magnetic quantities, magnetic devices, and materials used in practice. While retaining much of the original, this revision now covers SQUID and alternating gradient magnetometers, magnetic force microscope, Kerr effect, amorphous alloys, rare-earth magnets, SI Units alongside cgs units, and other up-to-date topics. In addition, the authors have added an entirely new chapter on information materials. The text presents materials at the practical rather than theoretical level, allowing for a physical, quantitative, measurement-based understanding of magnetism among readers, be they professional engineers or graduate-level students.