Ferromagnetic Materials

Below is a copy of Professor Takeshi Takei's original preface that he wrote for my first book, Modem Ferrite Teclmology. I was proud to receive this preface and include it here with pride and affection. We were saddened to learn of his death at 92 on March 12, 1992. Preface It is now some 50 years since ferrites debuted as an important new category of magnetic materials. They were prized for a range of properties that had no equivalents in existing metal magnetic materials, and it was not long before full-fledged research and development efforts were underway. Today, ferrites are employed in a truly wide range of applications, and the efforts of the many men and women working in the field are yielding many highly intriguing results. New, high-performance products are appearing one after another, and it would seem we have only scratched the surface of the hidden possibilities of these fascinating materials. Dr. Alex Goldman is well qualified to talk about the state of the art in ferrites. For many years Dr. Goldman has been heavily involved in the field as director of the research and development division of Spang & Co. and other enterprises. This book, Modem Ferrite Technology, based in part on his own experiences, presents a valuable overview of the field. It is testimony to his commitment and bountiful knowledge about one oftoday's most intriguing areas of technology.

"Volume 20 of the Handbook of Magnetic Materials, as the preceding volumes, has a dual purpose. As a textbook it is intended to help those who wish to be introduced to a given topic in the field of magnetism without the need to read the vast amount of literature published. As a work of reference it is intended for scientists active in magnetism research. To this dual purpose, Volume 20 is composed of topical review articles written by leading authorities. In each of these articles an extensive description is given in graphical as well as in tabular form, much emphasis being placed on the discussion of the experimental material in the framework of physics, chemistry and material science. It provides readers with novel trends and achievements in magnetism"--Publisher's note.

This book covers both basic physics of ferromagnetism, such as magnetic moment, exchange coupling, magnetic anisotropy, and recent progress in advanced ferromagnetic materials. Special focus is placed on NdFeB permanent magnets and the materials studied in the field of spintronics (explaining the development of tunnel magnetoresistance effect through the so-called giant magnetoresistance effect).

Handbook of Magnetic Materials, Volume 29, highlights new advances in the field, with this new volume presenting interesting chapters written by an international board of authors on topics such as spin-orbit torque. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Handbook of Magnetic Materials series

This book covers the properties and structure of a wide range of magnetic materials with engineering applications. It discusses ferromagnetic, ferrigmagnetic, and amorphous materials and their role in the two major property groupings of high permeability and permanent-magnet materials. Other groups, including materials suitable for magnetic recording, magnetoelastic transducers, magneto-optical discs and magnetic bubble memories, are also included. The book providesan in-depth discussion of the basic mechanisms which determine magnetic properties, and features a comprehensive view of how the mechanisms of magnetization reversal and coercivity are related to and interpreted in terms of the structure of the various materials at both the atomic and microstructural levels. For ease of location of materials and topics, the chapters are structured with numbered headings. A large amount of information is presented in textual, tabular, and graphical form, and extensive references will direct the reader to the most important or most representative original papers or reviews. The book is aimed at research students in materials science and electrical engineering, and industrial researchers, for whom the concentration on useful materials will be of particular interest. Covers a wide range of ferromagnetic materials, including many permanent magnets currently under development or research Provides a clear interpretation of the observed properties of ferromagnetic materials or magnetic ceramics in terms of crystal and magnetic structure Presents a detailed discussion and interpretation of magnetic properties of 3.2% Si-Fe transformer core alloy Features extensive references, with easy access to specific materials or topics

Magnetoelectronics is a novel and rapidly developing field. This new field is frequently referred to as spin-electronics or spintronics. It includes spin-utilizing devices that need neither a magnetic field nor magnetic materials. In semiconductor devices, the spin of the carriers has only played a very modest role so far because well established semiconductor devices are non-magnetic and show only negligible effects of spin. Nanoscale thin films and multilayers, nanocrystalline magnetic materials, granular films, and amorphous alloys have attracted much attention in the last few decades, in the field of basic research as well as in the broader field of materials science. Such heterogeneous materials display uncommon magnetic properties that virtually do no occur in bulk materials. This is true, in particular with respect to surface (interface) magnetic anisotropy and surface (interface) magnetostrictive strains and giant magnetoresistance. The local atomic arrangement at the interface differs strongly from that in the bulk. The local symmetry is lowered, so that some interactions are changed or are missing altogether.The interface atoms may envisaged as forming a new phase and some properties characteristic of this phase may become predominant for the entire system.This becomes particularly evident in the case of interfacial magnetostriction which can lead to a decrease (almost to zero) or to an increase(over the bulk value) of the resulting magnetostriction of the nanoscale system.There are various forms of the interplay of magnetism and superconductivity, which can be divided into competition and coexistence phenomena. For instance, a strong competition is found in high-Tc cuprates. In these materials, depending on the doping rate, either Neel-type antiferromagnetism moments (e.g. from 4f-elements) with superconductivity is known to occur in systems where the concentration of these moments is sufficiently small or where they are antiferromagnetically ordered and only weakly coupled to the conduction electrons.During the years, intermetallic gadolinium compounds have adopted a special position in the study of 4f electron magnetism. The reason for this is the fact that the gadolinium moment consists only of a pure spin moment, orbital contributions to the moment being absent. As a consequence, gadolinium compounds have been regarded as ideal test benches for studying exchange interactions, free from complications due to crystal effects.Volume 14 of the Handbook of Magnetic Materials, as the preceding volumes, has a dual purpose. As a textbook it is intended to be of assistance to those who wish to be introduced to a given topic in the field of magnetism without the need to read the vast amount of literature published. As a work of reference it is intended for scientists active in magnetism research. To this dual purpose, volume 14 of the Handbook is composed of topical review articles written by leading authorities. In each of these articles an extensive description is given in graphical as well as tabular form, much emphasis being placed on the discussion of the experimental material in the framework of physics, chemistry and material science.

Magnetic Materials is an excellent introduction to the basics of magnetism, magnetic materials and their applications in modern device technologies. Retaining the concise style of the original, this edition has been thoroughly revised to address significant developments in the field, including the improved understanding of basic magnetic phenomena, new classes of materials, and changes to device paradigms. With homework problems, solutions to selected problems and a detailed list of references, Magnetic Materials continues to be the ideal book for a one-semester course and as a self-study guide for researchers new to the field. New to this edition: • Entirely new chapters on Exchange Bias Coupling, Multiferroic and Magnetoelectric Materials, Magnetic Insulators • Revised throughout, with substantial updates to the chapters on Magnetic Recording and Magnetic Semiconductors, incorporating the latest advances in the field • New example problems with worked solutions

In a new branch of physics and technology, called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. This book is intended to provide an introduction and guide to the new physics and applications of spin current.