bluuebunny/crossref_metadata_2025_split huggingface dataset:
The
K
ondo Effect
Authors: Jones Barbara A. 
Published: December 2007

Abstract

A review is presented of the Kondo effect, with a summary of key experiments and theoretical treatments. Hamiltonians surveyed, in addition to the single‐impurity spin‐1/2 Kondo model, are multichannel Kondo models, the Coqblin–Schrieffer model, two‐impurity problems, including two‐channel, two‐impurity, the Anderson model, and a brief summary of the Kondo lattice. Exact, known results are a focus. Non‐Fermi‐liquid fixed points are a feature of more than one Kondo Hamiltonian, and the phases of these systems can be unusual and quite interesting. Techniques surveyed include scaling, numerical renormalization group, 1/
N
expansion, Bethe ansatz, and conformal field theory. We conclude with a review of the scanning tunneling microscope experiments on Kondo systems, one of the best current realizations of few‐impurity Kondo models, and a source of often surprising new physics.
Magnetic Spectroscopy
Authors: Ebert H. 
Published: December 2007

AbstractElectron spectroscopic methods are indispensable tools to study magnetic solids, as they can be used to monitor their magnetization in a spatial time‐resolved way and partly in an element‐resolved way, as well as to probe their electronic structure in a most detailed way. This contribution gives an overview on three representative and important techniques widely used for these purposes: magneto‐optics, X‐ray absorption, and photoemission spectroscopy. The theoretical basis for dealing with these spectroscopies is presented putting some emphasis on the consequences of spin‐orbit coupling, as this relativistic effect often plays a central role. After introducing the main concepts for each type of spectroscopy, some illustrative examples are presented.
Dissipative Magnetization Dynamics Close to the Adiabatic Regime
Authors: Fähnle Manfred , Steiauf Daniel 
Published: December 2007

AbstractThe article reviews the theory of dissipative spin dynamics close to the adiabatic regime, which encompasses the timescales from several picoseconds to several nanoseconds typical for long‐wavelength spin waves, for ultrafast magnetization dynamics of the domain walls, or for field‐ and current‐induced switching processes in nanostructures. The emphasis is on single‐phase systems, but links to magnetization dynamics in multilayer systems are also given. After an introduction of the appropriate magnetic dynamical variables for various experiments, the concept of dissipation is discussed. Two situations without damping, that is, the case of infinite electronic scattering time and the case of zero electronic scattering time (‘strictly adiabatic limit’) are considered, and the various physical mechanisms leading to finite scattering times are surveyed qualitatively. Two quantitative models for dissipative spin dynamics are discussed, the s–d model and the breathing Fermi surface model. The latter model is a very powerful tool to describe dissipative spin dynamics in metallic magnets for the limit of small scattering times, and it can be combined with the modern state‐of‐the‐art electronic density‐functional theory. The results of such calculations are reviewed, with special emphasis to the startling properties of damping in systems with reduced dimensionality. The status of the development of parameter‐free,ab initiospin dynamics simulation codes is discussed, and finally concluding remarks and perspectives are given.
Enhanced Magnetoresistance
Authors: Zahn Peter , Mertig Ingrid 
Published: December 2007

Abstract

The phenomenon of giant magnetoresistance (GMR) found in metallic multilayers will be discussed as an example for enhanced magnetoresistance in artificially structured systems. Theoretical formalisms based on ideas of Boltzmann, Landauer, and Kubo are capable of describing the electronic transport in layered structures and have been sketched in this chapter. The microscopic origin of GMR, the coherent band structure of the system, and the scattering at defects and imperfections are discussed by means of
ab initio
calculations based on density‐functional theory (DFT). Trends for the spin asymmetry of scattering will be given in comparison with the resulting resistivities and GMR ratios for the standard systems of magnetoelectronics.
General Micromagnetic Theory
Authors: Kronmüller Helmut 
Published: December 2007

Abstract
The objective of this contribution is a review of the principles of the continuum theory of micromagnetism and to show its applications to the main static and dynamic problems of ferromagnetic materials. Micromagnetism as a continuum theory closes the gap between quantum theory, dealing with atomic scales and the Maxwell theory dealing with macroscopic dimensions. Micromagnetism therefore corresponds to the tool to deal with nano‐ and microscales. Micromagnetism has become an indispensable theory for a fundamental understanding of magnetic domain configurations, magnetization processes and the interaction between magnetization and microstructures. After Landau–Lifshitz's wall calculations in 1935 and Brown's publication of the so‐called Brown's micromagnetic equations in 1940/1941, micromagnetism became the standard method to analyze the basic magnetic properties of ferromagnetic materials in the range of nano‐ and microscales.
The following review gives a brief presentation of the different energy terms involved in the magnetic Gibbs free energy and a derivation of the micromagnetic equilibrium conditions and of the effective field. Some characteristic applications illustrate the effectiveness of micromagnetism in the case of domain walls, nucleation problems, interaction with microstructures, domain patterns, and the dynamics of magnetization processes.
This contribution also gives a definition of the different exchange lengths related to dipolar fields, magnetocrystalline anisotropy energy, magnetostatic energy of external fields and the magnetoelastic coupling energy.

Whereas only a few cases exist where analytical solutions of the highly nonlinear micromagnetic equations are available the progress in computational micromagnetism allowed the numerical solution of many open problems, which will be treated in the following contributions by Miltat
et al.
, Schrefl
et al.
and D. Goll.
The Motion of Domain Walls in Nanocircuits and its Application to Digital Logic
Authors: Cowburn Russell P. 
Published: December 2007

Abstract
Magnetic nanowires form excellent structures for transmitting magnetic domain walls around a network. If the magnetization direction within magnetic domains is taken to represent data values, the nanowires can be used to transport information around an integrated circuit. Furthermore, careful shaping of the nanowires allows Boolean logic functions to be performed on the information, resulting in a nontransistor implementation of digital logic. In this chapter, experimental demonstrations are shown of all of the basic Boolean logic gates, as well as of nanocircuits containing multiple gates. The advantages and limitations of domain‐wall logic are discussed, and the possibilities of ultrahigh‐density three‐dimensional data storage are demonstrated.
Spin Structures and Spin Wave Excitations
Authors: Zaliznyak Igor A. 
Published: December 2007

Abstract
Electronic spin interactions and the resulting spin structures which give rise to various kinds of magnetism existing in many‐electron condensed matter systems are discussed. In most cases, spin structure and excitations in a spin system can be understood in the framework of semiclassical spin‐wave theory. Basic examples observed in magnetic neutron diffraction and inelastic magnetic neutron scattering experiments are presented and discussed with reference to such description. Relationship between the structure of the crystal lattice and spin arrangement and energy dispersion of spin excitations in the crystal are discussed and illustrated by some recent experimental results.
Time‐resolved
K
err‐effect and Spin Dynamics in Itinerant Ferromagnets
Authors: Koopmans Bert 
Published: December 2007

Abstract
The availability of femtosecond pulsed‐laser sources in combination with the development of time‐resolved and sensitive magneto‐optical schemes, have paved the way toward the exploration of the dynamics of spin systems at ultimate time scales. This chapter focuses on the exploration of subpicosecond processes in itinerant ferromagnet systems, which after a decade of research has now become an exciting and mature field of research. Both the potential and limitations of the experimental techniques, mostly concentrating on all‐optical approaches, and the subtle relation with processes being probed are being explained. The main part, though, is devoted to a review of experimental efforts and the physical insight that has emerged for the complementary spin‐dependent processes being investigated: populational dynamics (including state‐filling effects such as dichroic bleaching and direct transfer of angular momentum from the laser field), loss of magnetic order after laser heating, laser‐induced modification of anisotropy (including dynamics of exchange‐coupled systems)–triggering precessional phenomena, and the very recently discovered possibility to generate magnetic order at ultrafast timescales by driving metamagnetic phase transitions.
Spin‐polarized Photoelectron Spectroscopy as a Probe of Magnetic Systems
Authors: Johnson Peter David , Güntherodt Gernot 
Published: December 2007

Abstract

Spin‐polarized photoelectron spectroscopy has developed into a versatile tool for the study of surface and thin‐film magnetism. In this chapter, we examine the methodology of the technique and its recent application to a number of different problems. We first examine the photoemission process itself followed by a detailed review of spin‐polarization measurement techniques and the related experimental requirements. We review studies of spin‐polarized surface states, interface states, and quantum‐well states followed by studies of the technologically important oxide systems including half‐metallic transition‐metal oxides, ferromagnet/oxide interfaces and the antiferromagnetic cuprates that exhibit high
T
c
Superconductivity. We also discuss the application of high‐resolution photoemission with spin resolving capabilities to the study of spin‐dependent self‐energizing effects.
Magnetostrictive Materials and Magnetic Shape Memory Materials
Authors: O'Handley Robert C. 
Published: December 2007

AbstractThe coupling between the state of magnetization and the shape of a magnetic material is an interesting field, rich in basic science and opportunities for technical applications. Key experimental observations of conventional, anisotropic magnetostriction (the anisotropic strain tensor that rotates with the direction of magnetization in a free magnetic sample) are explained and the theoretical models of magnetostriction and related effects (e.g., the ΔEeffect and stress‐induced anisotropy) are described. A new effect, quite distinct from anisotropic magnetostriction, is the large magnetic‐field‐induced strain observed in certain magnetic shape memory alloys. While these materials do exhibit conventional anisotropic magnetostrictive strain (of the order of 10−4), their 6–10% field‐induced strain is due to twin boundary motion, which may or may not occur under magnetization rotation depending on the extent to which the twin boundaries are pinned on defects.
Advanced Soft Magnetic Materials for Power Applications
Authors: Moses Anthony J. 
Published: December 2007

AbstractThis article begins by introducing the importance of electrical steels in their application as electrical machine cores. Nonoriented, grain‐oriented, and high‐silicon steels comprise over 97% of the world's production of soft magnetic materials. The origin, controlling factors, and methods of optimizing their most important magnetic parameter, the core loss, are discussed. The effect of magnetizing frequency, flux density, mechanical stress, temperature, and flux distortion is shown. Magnetostriction is a further factor of importance in many devices, so this is briefly discussed. There is a growing interest in predicting the losses of electrical steels, so the need for better understanding of magnetization processes to build accurate models which will cater to the more stringent specifications of modern industry are discussed, and new approaches are reviewed. Powder composite materials are finding niche applications in power devices, so their magnetic properties are compared with those of the traditional lamination steels. The paper does not cover magnetically soft ferrites or iron–cobalt alloys which are used in specialized power magnetic applications.
Application of Magnetic Particles in Medicine and Biology
Authors: Andrä Wilfried , Häfeli Urs , Hergt Rudolf , Misri Ripen 
Published: December 2007

AbstractMagnetic particles (MPs) have proved to be valuable tools for manipulation of cells or biomolecules, for transportation of chemical substances or transfer of energy to defined target sites in biological systems, and for clinical diagnostics and therapeutics—bothin vitroas well asin vivo. MPs receive their magnetic properties and responsiveness to magnetic fields most often from the proven biocompatible iron oxides magnetite (Fe3O4) and maghemite (γ‐Fe2O3). The small size of MPs allows them to pass through capillary vessels during blood circulation. In nanoparticulate form or under the influence of strong magnetic fields, some MPs can even extravasate through capillary walls into surrounding tissue and reach many of the cells in the human body. Magnetically assisted delivery of chemo‐ or radiotherapeutics to as well as the generation of heat (hyperthermia) at defined target sites in the body can thus be achieved for treatment purposes, such as tumor therapy. Furthermore, MPs can serve as site‐ and function‐specific contrast agents and thus enhance the diagnostic potential of magnetic resonance imaging (MRI). On the biotechnological side, magnetic labeling of cells and biomolecules with MPs followed by magnetic separation has been utilized for the isolation and analysis of nucleic acids and specific cells, for protein purification, for the detection of pathogenic bacteria and viruses, and for gene transfection.
Theory of Spin Hall Effects in Semiconductors
Authors: Engel Hans‐Andreas , Rashba Emmanuel I. , Halperin Bertrand I. 
Published: December 2007

Abstract
Spin Hall effects are a collection of phenomena, resulting from spin‐orbit coupling, in which an electrical current flowing through a sample can lead to spin transport in a perpendicular direction and spin accumulation at lateral boundaries. These effects, which do not require an applied magnetic field, can originate in a variety of intrinsic and extrinsic spin‐orbit coupling mechanisms and depend on geometry, dimension, impurity scattering, and carrier density of the system—making the analysis of these effects a diverse field of research. In this chapter, we give an overview of the theoretical background of the spin Hall effects and summarize some of the most important results. First, we explain effective spin‐orbit Hamiltonians, how they arise from band structure, and how they can be understood from symmetry considerations; including intrinsic coupling due to bulk inversion or structure asymmetry or due to strain, and extrinsic coupling due to impurities. This leads to different mechanisms of spin transport: spin precession, skew scattering, and side jump. Then we present the kinetic (Boltzmann) equations, which describe the spin‐dependent distribution function of charge carriers, and the diffusion equation for spin‐polarization density. Next, we define the notion of spin currents and discuss their relation to spin polarization. Finally, we explain the electrically induced spin effects; namely, spin polarization and currents in bulk and near boundaries (the focus of most current theoretical research efforts), and spin injection, as well as effects in mesoscopic systems and in edge states.
Spin Angular Momentum Transfer in Magnetoresistive Nanojunctions
Authors: Sun Jonathan Z. 
Published: December 2007

Abstract
High current density spin‐polarized transport in current‐perpendicular nanomagnetic junctions reveals an interaction between the spin‐polarized current and the nanomagnet electrodes. This interaction causes a current‐induced magnetic excitation in the ferromagnetic electrodes, leading either to persistent magnetic precession or to a complete magnetic reversal, under a dc current bias. This article gives a brief review of the basic understanding of this so‐called spin‐transfer phenomenon, including the basic mechanism, its early theoretical prediction and experimental discovery, and the significance of this interaction for applications in modern electronics. This review uses a framework of phenomenological analyses, bridging experimental observations and first‐principle‐based theoretical work.
Tunneling Magnetoresistance in Semiconductors
Authors: Ohya Shinobu , Tanaka Masaaki 
Published: December 2007

AbstractWe overview the studies on tunneling magnetoresistance (TMR) in monocrystalline semiconductor‐based magnetic tunnel junctions (MTJs). Emphasis is placed on spin‐polarized tunneling in GaMnAs‐based heterostructure MTJs with a single barrier and double barriers grown by molecular‐beam epitaxy. Additionally, recently observed new phenomena related to spin‐polarized tunneling are also described.
Electrode Potentials
Authors: Petrii Oleg A. , Tsirlina Galina A. 
Published: December 2007

AbstractThe sections in this article areIntroductory RemarksExternal and Internal PotentialsElectromotive Force (emf) and Gibbs Energy of ReactionDiffusion Potential DropClassification of ElectrodesMembrane ElectrodesStandard PotentialsSpecific Features of Certain Reference ElectrodesValues of Redox PotentialsPotential WindowsExperimental TechniquesEffects of Ion PairingAbsolute Electrode PotentialThe Role of Electric Double LayersConclusion
Electrochemical Double Layers: Liquid–Liquid Interfaces
Authors: Volkov Alexander G. , Markin Vladislav S. 
Published: December 2007

Abstract
The sections in this article are

Polarizable and Nonpolarizable Liquid Interfaces

Verwey–Niessen Model

The Electrocapillary Equation

Zero‐Charge Potentials

Specific Adsorption at Liquid–Liquid Interfaces

Adsorption Isotherm

Image Forces

Modified Poisson–Boltzmann (
MPB
) Model
Polyelectrolytes in Solution and at Surfaces
Authors: Netz Roland R. , Andelman David 
Published: December 2007

Abstract
This chapter deals with charged polymers (polyelectrolytes) in solution and at surfaces. The behavior of polyelectrolytes (PEs) is markedly different from that of neutral polymers. In bulk solutions, that is, disregarding the surface effect, there are two unique features to charged polymers: first, owing to the presence of long‐ranged electrostatic repulsion between charged monomers, the polymer conformations are much more extended, giving rise to a very small overlap concentration and high solution viscosity. Second, the presence of a large number of counterions increases the osmotic pressure of PE solutions, making such polymers water soluble as this is of great importance to many applications. At surfaces, the same interplay between monomer–monomer repulsion and counterion degrees of freedom leads to a number of special properties. In particular, the adsorption behavior depends on both the concentration of polymers and the added salt in the bulk. We first describe the adsorption behavior of single PE molecules and discuss the necessary conditions to obtain an adsorbed layer and characterize its width. Depending on the stiffness of the PE, the layer can be flat and compressed or coiled and extended. We then proceed and discuss the adsorption of PEs from semidilute solutions. Mean‐field theory profiles of PE adsorption are calculated as a function of surface charge density (or surface potential), the amount of salt in the system, and the charge fraction on the chains. The phenomenon of charge inversion is reviewed and its relevance to the formation of multilayers is explained. The review ends with a short overview of the behavior of grafted PEs.
The Current–Potential Relationship
Authors: Calvo Ernesto J. 
Published: December 2007

AbstractThe sections in this article areScopeIntroductionThermodynamics of Electrochemical CellsTheButler–Volmer EquationTheory of Electron TransferIon‐Transfer ReactionsMultiple Electron TransferStoichiometric NumberMass Transport at ElectrodesElectrochemical Reaction OrderDouble‐Layer Effects on the Current–potential RelationshipAdsorption and ElectrocatalysisMixed PotentialElectrocrystallizationAcknowledgments
Electrocatalysis
Authors: Herrero Enrique , Feliu Juan M. , Aldaz Antonio 
Published: December 2007

Abstract
The sections in this article are

Introduction: Concept of Electrocatalysis and Electrocatalyst

Electronic Effects in Electrocatalysis

Specific Interaction and Transfer Rates

Adsorption and Electrocatalysis

Surface Structure Effects

Role of the Surface Symmetry in Electrocatalysis

Chiral Surfaces

Surface Composition Effects

Changes in the Electronic Properties of the Metal

Ensemble Effects

Bifunctional Catalysts

Modeling of the Catalytic Effects
Electrochemical Nucleation and Growth
Authors: Scharifker Benjamin R. , Mostany Jorge 
Published: December 2007

AbstractThe sections in this article arePhase Formation on ElectrodesThermodynamics of Electrochemical Phase FormationElectrochemical Nucleation KineticsThe Classical Nucleation ModelNucleation on Electrode SurfacesMicroscopic Approach to Phase Formation: The Atomistic ModelExperimental Studies of Electrochemical Phase FormationThree‐dimensional NucleationTwo‐dimensional ElectrocrystallizationSpatial Distribution of NucleiExperimental Examples
Spectroelectrochemistry: In
s
itu
UV
‐visible Spectroscopy
Authors: Crayston Joe A. 
Published: December 2007

Abstract
The sections in this article are

Introduction and Principles

Introductory Remarks

Theory and Techniques: Steady State Measurement

Cell Transmission for a Simple Electron Transfer Reaction: Determination of
E
and
n

Effect of Follow‐up Reactions in
OTTLE
Cells

Theory and Techniques: Kinetic Measurements

Chronoabsorptometry

Instrumentation for Chronoabsorptometry

Slow Heterogeneous Kinetics

Effect of Follow‐up Reactions

Derivative Cyclic Voltabsorptometry (
DCVA
)

Galvanostatic Conditions

Adsorption

Cell Geometries, Design, Techniques, and Instrumentation

General Considerations

Transmission under Thin‐layer Conditions:
OTTLEs
and Flow‐cells

Variations on and Alternatives to the Basic
OTTLE
Design

OTTLE
Cells Intended for Both
UV
‐visible and
FTIR
Use

OTTLE
Cell Electrochemical and Spectroscopic Response

Semi‐infinite Cells: Optically Transparent Electrodes (
OTEs
)

Reflection from Electrodes and Liquid–Liquid Interfaces

Glancing Incidence Reflection, Near‐parallel or Parallel Reflection, and Diffraction

Liquid–Liquid Interface and Attenuated Total Reflection

Long Optical Path‐length Thin‐layer Cell (
LOPTLC
)

Forced Convection,
RDE
and Channel Flow

UV
‐vis Combined with Other Spectroscopic Techniques

Applications

Solution Studies of Inorganic Species

Solution Studies of Organic Species

Molten Salts Spectroelectrochemistry

Studies of Species of Biological Interest

Inorganic Thin Films and Modified Electrodes

Conducting Polymers and Oligomer Models

Conclusions
Thermodynamics of Electrolytic Corrosion
Authors: Frankel Gerald S. , Landolt Dieter 
Published: December 2007

Abstract
The sections in this article are

Introduction

Fundamentals of Thermodynamics

Thermodynamics of Electrochemical Reactions

Example 1

Example 2

Example 3

N
ernst Equation

Example 3

Cathodic Reactions in Corrosion

P
ourbaix Diagrams

P
ourbaix Diagram for Water

P
ourbaix Diagram for Metals

Example:
P
ourbaix Diagram for
Fe

Comments on
P
ourbaix Diagrams

Thermodynamics of High Temperature Corrosion