Ferromagnetism of metallic systems, especially those including transition metals, has been a controversial subject of modern science for a long time. This controversy sterns from the apparent dual character of the d-electrons responsible for magnetism in transition metals, i.e., they are itinerant elec trons described by band theory in their ground state, while at finite tem peratures they show various properties that have long been attributed to a system consisting of local magnetic moments. The most familiar example of these properties is the Curie-Weiss law of magnetic susceptibility obeyed by almost all ferromagnets above their Curie temperatures. At first the problem seemed to be centered around whether the d-elec trons themselves are localized or itinerant. This question was settled in the 1950s and early 1960s by various experimental investigations, in particular by observations of d-electron Fermi surfaces in ferromagnetic transition metals. These observations are generally consistent with the results of band calculations. Theoretical investigations since then have concentrated on explaining this dual character of d-electron systems, taking account of the effects of electron-electron correlations in the itinerant electron model. The problem in physical terms is to study the spin density fluctuati·ons, which are ne glected in the mean-field or one-electron theory, and their influence on the physical properties.
A summary of recent developments in theoretical and experimental studies of fluctuation effects in itinerant electron magnets, focusing on novel physical phenomena: soft-mode spin fluctuations and zero-point effects, strong spin anharmonicity, magnetic frustrations in metals, fluctuation effects in Invar alloys and low-dimensional systems. All of these may be important for novel high-technology applications.
This volume shows how collective magnetic excitations determine most of the magnetic properties of itinerant electron magnets. Previous theories were mainly restricted to the Curie-Weiss law temperature dependence of magnetic susceptibilities. Based on the spin amplitude conservation idea including the zero-point fluctuation amplitude, this book shows that the entire temperature and magnetic field dependence of magnetization curves, even in the ground state, is determined by the effect of spin fluctuations. It also shows that the theoretical consequences are largely in agreement with many experimental observations. The readers will therefore gain a new comprehensive perspective of their unified understanding of itinerant electron magnetism.
In December 2002, the world's first commercial magnetic levitation super-train went into operation in Shanghai. The train is held just above the rails by magnetic levitation (maglev) and can travel at a speed of 400 km/hr, completing the 30km journey from the city to the airport in minutes. Now consumers are enjoying 50 GB hard drives compared to 0.5 GB hard drives ten years ago. Achievements in magnetic materials research have made dreams of a few decades ago reality. The objective of the four volume reference, Handbook of Advanced Magnetic Materials, is to provide a comprehensive review of recent progress in magnetic materials research. Each chapter will have an introduction to give a clear definition of basic and important concepts of the topic. The details of the topic are then elucidated theoretically and experimentally. New ideas for further advancement are then discussed. Sufficient references are also included for those who wish to read the original work. In the last decade, one of the most significant thrust areas of materials research has been nanostructured magnetic materials. There are several critical sizes that control the behavior of a magnetic material, and size effects become especially critical when dimensions approach a few nanometers, where quantum phenomena appear. The first volume of the book, Nanostructured Advanced Magnetic Materials, has therefore been devoted to the recent development of nanostructured magnetic materials, emphasizing size effects. Our understanding of magnetism has advanced with the establishment of the theory of atomic magnetic moments and itinerant magnetism. Simulation is a powerful tool for exploration and explanation of properties of various magnetic materials. Simulation also provides insight for further development of new materials. Naturally, before any simulation can be started, a model must be constructed. This requires that the material be well characterized. Therefore the second volume, Characterization and Simulation provides a comprehensive review of both experimental methods and simulation techniques for the characterization of magnetic materials. After an introduction, each section gives a detailed description of the method and the following sections provide examples and results of the method. Finally further development of the method will be discussed. The success of each type of magnetic material depends on its properties and cost which are directly related to its fabrication process. Processing of a material can be critical for development of artificial materials such as multilayer films, clusters, etc. Moreover, cost-effective processing usually determines whether a material can be commercialized. In recent years processing of materials has continuously evolved from improvement of traditional methods to more sophisticated and novel methods. The objective of the third volume, Processing of Advanced Magnetic Materials, is to provide a comprehensive review of recent developments in processing of advanced magnetic materials. Each chapter will have an introduction and a section to provide a detailed description of the processing method. The following sections give detailed descriptions of the processing, properties and applications of the relevant materials. Finally the potential and limitation of the processing method will be discussed. The properties of a magnetic material can be characterized by intrinsic properties such as anisotropy, saturation magnetization and extrinsic properties such as coercivity. The properties of a magnetic material can be affected by its chemical composition and processing route. With the continuous search for new materials and invention of new processing routes, magnetic properties of materials cover a wide spectrum of soft magnetic materials, hard magnetic materials, recording materials, sensor materials and others. The objective of the fourth volume, Properties and Applications of Advanced Magnetic Materials, is to provide a comprehensive review of recent development of various magnetic materials and their applications. Each chapter will have an introduction of the materials and the principles of their applications. The following sections give a detailed description of the processing, properties and applications. Finally the potential and limitation of the materials will be discussed.
This three-volume book provides a comprehensive review of experiments in very strong magnetic fields that can only be generated with very special magnets. The first volume is entirely devoted to the technology of laboratory magnets: permanent, superconducting, high-power water-cooled and hybrid; pulsed magnets, both nondestructive and destructive (megagauss fields). Volumes 2 and 3 contain reviews of the different areas of research where strong magnetic fields are an essential research tool. These volumes deal primarily with solid-state physics; other research areas covered are biological systems, chemistry, atomic and molecular physics, nuclear resonance, plasma physics and astrophysics (including QED).
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.
High temperature superconductivity is still one of the most discussed topicsin physics. "The Physics and Chemistry of Oxide Superconductors " collects together more than one hundred original contributions presented during the 2nd International Symposium of the Institute for Solid State Physics of the University of Tokyo. The main topics cover new insights into the basic mechanism of high temperature superconductivity, recent developments of new superconducting materials, the state of the art of thin film production,theoretical understanding of the electronic structures in this kind of material, theories for strongly correlated electron systems, and many physical and chemical effects.
The book introduces scientists and graduate students to superconductivity, and highlights the differences arising from the different dimensionality of the sample under study. It focuses on transport in one-dimensional superconductors, describing relevant theories with particular emphasis on experimental results. It closely relates these results to the emergence of various novel fabrication techniques. The book closes by discussing future perspectives, and the connection and relevance to other physical systems, including superfluidity, Bose-Einstein condensates, and possibly cosmic strings.
This book represents recent cutting-edge developments in low temperature physics, reported at one of the largest international conferences in physics. The subjects covered are superconductivity, magnetism, quantum gases, quantum liquids and solids, electronic properties of solids, low-temperature experimental techniques, cryogenics, and applications.
