Spin Fluctuations in Itinerant Electron Magnetism


Book Description

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.




Spin Fluctuation Theory of Itinerant Electron Magnetism


Book Description

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.




Itinerant Electron Magnetism: Fluctuation Effects


Book Description

Proceedings of the NATO Advanced Research Workshop on Itinerant Electron Magnetism: Fluctuation Effects & Critical Phenomena, Moscow, Russia, September 15-19, 1997







Lecture Notes on Electron Correlation and Magnetism


Book Description

This volume attempts to fill the gap between standard introductions to solid state physics, and textbooks which give a sophisticated treatment of strongly correlated systems. Starting with the basics of the microscopic theory of magnetism, one proceeds with relatively elementary arguments to such topics of current interest as the Mott transition, heavy fermions, and quantum magnetism. The basic approach is that magnetism is one of the manifestations of electronOCoelectron interaction, and its treatment should be part of a general discussion of electron correlation effects. Though the text is primarily theoretical, a large number of illustrative examples are brought from the experimental literature. There are many problems, with detailed solutions. The book is based on the material of lectures given at the Diploma Course of the International Center for Theoretical Physics, Trieste, and later at the Technical University and the R. EAtvAs University of Budapest, Hungary. Sample Chapter(s). Chapter 1.1: Magnetism and Other Effects of Electron-Electron Interaction (483 KB). Chapter 1.2: Sources of Magnetic Fields (311 KB). Chapter 1.3: Getting Acquainted: Magnetite (692 KB). Chapter 1.4: Variety of Correlated Systems: An Outline of the Course (307 KB). Contents: Atoms, Ions, and Molecules; Crystal Field Theory; Mott Transition and Hubbard Model; Mott Insulators; Heinsenberg Magnets; Itinerant Electron Magnetism; Ferromagnetism in Hubbard Models; The Gutzwiller Variational Method; The Correlated Metallic State; Mixed Valence and Heavy Fermions; Quantum Hall Effect; Hydrogen Atom; Single-Spin-Flip Ansatz; Gutzwiller Approximation; SchriefferOCoWolff Transformation. Readership: Graduate students and researchers in condensed matter physics."










Spin Current


Book Description

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.




Spin Current


Book Description

Since the discovery of the giant magnetoresistance (GMR) effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. Recent progress in the physics of magnetism and the application of spin current has progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book is intended to provide an introduction and guide to the new physics and applications of spin current. The emphasis is placed on the interaction between spin and charge currents in magnetic nanostructures.