磁性

1 Introduction

1.1 Magnetism： Magical yet Practical

1.2 History of Magnetism

1.3 Magnetism， Neutrons， Polarized Electrons， and X-rays

1.3.1 Spin Polarized Electrons and Magnetism

1.3.2 Polarized X-rays and Magnetism

1.4 Developments in the Second Half of the 20th Century

1.5 Some Thoughts about the Future

1.6 About the Present Book

Part 1 Fields and Moments

2 Electric Fields， Currents， and Magnetic Fields

2.1 Signs and Units in Magnetism

2.2 The Electric Field

2.3 The Electric Current and its Magnetic Field

2.4 High Current Densities

2.5 Magnetic and Electric Fields inside Materials

2.6 The Relation of the Three Magnetic Vectors in Magnetic Materials

2.6.1 Stray and Demagnetizing Fields of Thin Films

2.6.2 Applications of Stray and Demagnetizing Fields

2.7 Symmetry Properties of Electric and Magnetic Fields

2.7.1 Parity

2.7.2 Time Reversal

3 Magnetic Moments and their Interactions with Magnetic Fields

3.1 The Classical Definition of the Magnetic Moment

3.2 From Classical to Quantum Mechanical Magnetic Moments

3.2.1 The Bohr Magneton

3.2.2 Spin and Orbital Magnetic Moments

3.3 Magnetic Dipole Moments in an External Magnetic Field

3.4 The Energy of a Magnetic Dipole in a Magnetic Field

3.5 The Force on a Magnetic Dipole in an Inhomogeneous Field

3.5.1 The Stern-Gerlach Experiment

3.5.2 The Mott Detector

3.5.3 Magnetic Force Microscopy

3.6 The Torque on a Magnetic Moment in a Magnetic Field

3.6.1 Precession of Moments

3.6.2 Damping of the Precession

3.6.3 Magnetic Resonance

3.7 Time-Energy Correlation

3.7.1 The Heisenberg Uncertainty Principle

3.7.2 Classical Spin Precession

3.7.3 Quantum Mechanical Spin Precession

4 Time Dependent Fields

4.1 Overview

4.2 Basic Concepts of Relativistic Motion

4.2.1 Length and Time Transformations Between Inertial Systems

4.2.2 Electric and Magnetic Field Transformations between Inertial Systems

4.3 Fields of a Charge in Uniform Motion： Velocity Fields

4.3.1 Characteristics of Velocity Fields

4.3.2 Creation of Large Currents and Magnetic Fields

4.3.3 Creation of Ultrashort Electron Pulses and Fields

4.3.4 The Temporal Nature of Velocity Fields

4.4 Acceleration Fields： Creation of EM Radiation

4.4.1 Polarized X-rays： Synchrotron Radiation

4.4.2 Brighter and Shorter X-ray Pulses： From Undulators to Free Electron Lasers

5 Polarized Electromagnetic Waves

5.1 Maxwells Equations and their Symmetries

5.2 The Electromagnetic Wave Equation

5.3 Intensity， Flux， Energy， and Momentum of EM Waves

5.4 The Basis States of Polarized EM Waves

5.4.1 Photon Angular Momentum “

5.4.2 Linearly Polarized Basis States

5.4.3 Circularly Polarized Basis States

5.4.4 Chirality and Angular Momentum of Circular EM Waves

5.4.5 Summary of Unit Polarization Vectors

5.5 Natural and Elliptical Polarization

5.5.1 Natural Polarization

5.5.2 Elliptical Polarization

5.5.3 The Degree of Photon Polarization

5.6 Transmission of EM Waves through Chiral and Magnetic Media

Part 2 History and Concepts of Magnetic Interactions

6 Exchange Spin-Orbit， and Zeeman Interactions

6.1 Overview

6.2 The Spin Dependent Atomic Hamiltonian or Pauli Equation

6.2.1 Independent Electrons in a Central Field

6.2.2 Interactions between two Particles - Symmetrization Postulate and Exclusion Principle

6.3 The Exchange Interaction

6.3.1 Electron Exchange in Atoms

6.3.2 Electron Exchange in Molecules

6.3.3 Magnetism and the Chemical Bond

6.3.4 From Molecules to Solids

6.3.5 The Heisenberg Hamiltonian

6.3.6 The Hubbard Hamiltonian

6.3.7 Heisenberg and Hubbard Models for H2

6.3.8 Summary and Some General Rules for Electron Exchange

6.4 The Spin-Orbit Interaction

6.4.1 Fine Structure in Atomic Spectra

6.4.2 Semiclassical Model for the Spin-Orbit Interaction

6.4.3 The Spin-Orbit Hamiltonian

6.4.4 Importance of the Spin-Orbit Interaction

6.5 Hunds Rules

6.6 The Zeeman Interaction

6.6.1 History and Theory of the Zeeman Effect

6.6.2 Zeeman Versus Exchange Splitting of Electronic States

6.6.3 Importance of the Zeeman Interaction

7 Electronic and Magnetic Interactions in Solids

7.1 Chapter Overview

7.2 Localized versus Itinerant Magnetism： The Role of the Centrifugal Potential

7.3 The Relative Size of Interactions in Solids

7.4 The Band Model of Ferromagnetism

7.4.1 The Puzzle of the Broken Bohr Magneton Numbers

7.4.2 The Stoner Model

7.4.3 Origin of Band Structure

7.4.4 Density b-hnctional Theory

7.5 Ligand Field Theory

7.5.1 Independent-Elecfron Ligand Field Theory

7.5.2 Multiplet Ligand Field Theory

7.6 The Importance of Electron Correlation and Excited States

7.6.1 Why are Oxides often Insulators？

7.6.2 Correlation Effects in Rare Earths and Transition Metdl Oxides

7.6.3 From Delocalized to Localized Behavior： Hubbard and LDA+U Models

7.7 Magnetism in Transition Metal Oxides

7.7.1 Superexchange

7.7.2 Double Exchange

7.7.3 Colossal Magnetoresistance

7.7.4 Magnetism of Magnetite

7.8 RKKY Exchange

7.8.1 Point-like Spins in a Conduction Electron Sea

7.8.2 Metallic Multilayers

7.9 Spin-Orbit Interaction： Origin of the Magnetocrystalline Anisotropy

7.9.1 The Bruno Model

7.9.2 Description of Anisotropic Bonding

7.9.3 Bonding， Orbital Moment， and Magnetocrystalline Anisotropy

Part 3 Polarized Electron and X-Ray Techniques

8 Polarized Electrons and Magnetism

8.1 Introduction

8.2 Generation of Spin-Polarized Electron Beams

8.2.1 Separation of the Two Spin States

8.2.2 The GaAs Spin-Polarized Electron Source

8.3 Spin-Polarized Electrons and Magnetic Materials： Overview of Experiments

8.4 Formal Description of Spin-Polarized Electrons

8.4.1 Quantum Behavior of the Spin

8.4.2 Single Electron Polarization in the Pauli Spinor Formalism

8.4.3 Description of a Spin-Polarized Electron Beam

8.5 Description of Spin Analyzers and Filters

8.5.1 Incident Beam Polarization： Spin Analyzer

8.5.2 Transmitted Beam Polarization： Spin Filter

……

Part 4 Properties of and Phenomena in the Ferromagnetic Metals

Part 5 Appendices

This book emerged from a close collaboration of the authors which started inthe fall of 2000. Early that year one of us （J.S.） had joined the Stanford facultyafter spending nearly 15 years at the IBM Almaden Research Center and theother （H.C.S.） had just retired from a chair at the ETH Ziirich and come toStanford as a visiting professor.