The Quantum Theory Of Magnetism

Magnetism is one of the oldest and most fundamental problems of Solid State Physics although not being fully understood up to now. On the other hand it is one of the hottest topics of current research. Practically all branches of modern technological developments are based on ferromagnetism, especially what concerns information technology. The book, written in a tutorial style, starts from the fundamental features of atomic magnetism, discusses the essentially single-particle problems of dia- and paramagnetism, in order to provide the basis for the exclusively interesting collective magnetism (ferro, ferri, antiferro). Several types of exchange interactions, which take care under certain preconditions for a collective ordering of localized or itinerant permanent magnetic moments, are worked out. Under which conditions these exchange interactions are able to provoke a collective moment ordering for finite temperatures is investigated within a series of theoretical models, each of them considered for a very special class of magnetic materials. The book is written in a tutorial style appropriate for those who want to learn magnetism and eventually to do research work in this field. Numerous exercises with full solutions for testing own attempts will help to a deep understanding of the main aspects of collective ferromagnetism.

This advanced level textbook is devoted to the description of systems which show ordered magnetic phases. A wide selection of topics is covered, including a detailed treatment of the mean-field approximation as the main paradigm for the phenomenological description of phase transitions. The book discusses the properties of low-dimensional systems and uses Green's functions extensively after a useful mathematical introduction. A thorough presentation of the RKKY and related models of indirect exchange is also featured, and a chapter on surface magnetism, rarely found in other textbooks, adds to the uniqueness of this book.For the second edition, three new chapters have been added, namely on magnetic anisotropy, on coherent magnon states and on local moments. Additionally, the chapter on itinerant magnetism has been enlarged by including a section on paramagnons.

"Quantum Theory of Magnetism" is the only book that deals with the phenomenon of magnetism from the point of view of "linear response". That is, how does a magnetic material respond when excited by a magnetic field? That field may be uniform, or spatially varying, static or time dependent. Previous editions have dealt primarily with the magnetic response. This edition incorporates the resistive response of magnetic materials as well. It also includes problems to test the reader's (or student's) comprehension. The rationale for a book on magnetism is as valid today as it was when the first two editions of Quantum Theory of Magnetism were published. Magnetic phenomena continue to be discovered with deep scientific implications and novel applications. Since the Second Edition, for example, Giant Magneto Resistance (GMR) was discovered and the new field of "spintronics" is currently expanding. Not only do these phenomena rely on the concepts presented in this book, but magnetic properties are often an important clue to our understanding of new materials (e.g., high-temperature superconductors). Their magnetic properties, studied by susceptibility measurements, nuclear magnetic resonance, neutron scattering, etc. have provided insight to the superconductivity state.This updated edition offers revised emphasis on some material as a result of recent developments and includes new material, such as an entire chapter on thin film magnetic multilayers. Researchers and students once again have access to an up-to-date classic reference on magnetism, the key characteristic of many modern materials.

Closing a gap in the literature, this volume is intended both as an introductory text at postgraduate level and as a modern, comprehensive reference for researchers in the field. Provides a full working description of the main fundamental tools in the theorists toolbox which have proven themselves on the field of quantum magnetism in recent years. Concludes by focusing on the most important cuurent materials form an experimental viewpoint, thus linking back to the initial theoretical concepts.

In the excitement and rapid pace of developments, writing pedagogical texts has low priority for most researchers. However, in transforming my lecture l notes into this book, I found a personal benefit: the organization of what I understand in a (hopefully simple) logical sequence. Very little in this text is my original contribution. Most of the knowledge was collected from the research literature. Some was acquired by conversations with colleagues; a kind of physics oral tradition passed between disciples of a similar faith. For many years, diagramatic perturbation theory has been the major theoretical tool for treating interactions in metals, semiconductors, itiner ant magnets, and superconductors. It is in essence a weak coupling expan sion about free quasiparticles. Many experimental discoveries during the last decade, including heavy fermions, fractional quantum Hall effect, high temperature superconductivity, and quantum spin chains, are not readily accessible from the weak coupling point of view. Therefore, recent years have seen vigorous development of alternative, nonperturbative tools for handling strong electron-electron interactions. I concentrate on two basic paradigms of strongly interacting (or con strained) quantum systems: the Hubbard model and the Heisenberg model. These models are vehicles for fundamental concepts, such as effective Ha miltonians, variational ground states, spontaneous symmetry breaking, and quantum disorder. In addition, they are used as test grounds for various nonperturbative approximation schemes that have found applications in diverse areas of theoretical physics.

Magnetism is a strange force, mysteriously attracting one object to another apparently through empty space. It has been claimed as a great healer, with magnetic therapies being proposed over the centuries and still popular today. Why are its mysterious important to solve? In this Very Short Introduction, Stephen J. Blundell explains why. For centuries magnetism has been used for various exploits; through compasses it gave us navigation and through motors, generators, and turbines it has given us power. Blundell explores our understanding of electricity and magnetism, from the work of Galvani, Ampere, Faraday, and Tesla, and goes on to explore how Maxwell and Faraday's work led to the unification of electricity and magnetism, thought of as one of the most imaginative developments in theoretical physics. With a discussion of the relationship between magnetism and relativity, quantum magnetism, and its impact on computers and information storage, Blundell shows how magnetism has changed our fundamental understanding of the Universe. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.

This advanced level textbook is devoted to the description of systems which show ordered magnetic phases. A wide selection of topics is covered, including a detailed treatment of the mean-field approximation as the main paradigm for the phenomenological description of phase transitions. The book discusses the properties of low-dimensional systems and uses Green's functions extensively after a useful mathematical introduction. A thorough presentation of the RKKY and related models of indirect exchange is also featured, and a chapter on surface magnetism, rarely found in other textbooks, adds to the uniqueness of this book.For the second edition, three new chapters have been added, namely on magnetic anisotropy, on coherent magnon states and on local moments. Additionally, the chapter on itinerant magnetism has been enlarged by including a section on paramagnons.

The book is intended for graduate students and researchers who wish to master the main properties of magnetic materials in the bulk state and at the nanometric scale such as for thin films and multilayers. This textbook provides the theories and methods of simulation to study and to understand these properties in an explicit manner.In the first part of the book, the quantum theory of magnetism is presented while the second part of the book is devoted to the application of the theory of magnetism to surface physics. Numerous examples covering typical cases in ferromagnets, antiferromagnets, ferrimagnets, helimagnets, and frustrated spin systems are all illustrated. Fundamental surface effects are shown and discussed. Lastly, the spin transport is described — in which the basic formulation of the Boltzmann's equation is recalled — and the recent methods of Monte Carlo simulation to deal with the spin resistivity are explained.This book contains a large number of detailed solutions for the problems given in each chapter to help readers discover new related phenomena and applications, as well as an appendix on elements of statistical physics included at the end to make the book self-contained.

This second edition extends and improves on the first, illustrating through myriad examples, the principles and logic used in extending the simple laws of idealised Newtonian physics and quantum physics into the real world of noise and thermal fluctuations.