1Intrinsic and Extrinsic Properties of Advanced Magnetic Materials1
1.1Introduction1
1.2Intrinsic Properties3
1.2.1Magnetic Moment3
1.2.2Exchange4
1.2.3Magnetization and Magnetic Order6
1.2.4Itinerant Magnetism8
1.2.5Magnetic Anisotropy10
1.3Extrinsic Properties14
1.3.1Coherent Rotation16
1.3.2Domains and Domain Walls18
1.3.3Coercivity21
1.4Magnetic Materials25
1.4.1Permanent Magnets25
1.4.2Soft Magnets27
1.4.3Recording Media28
1.4.4Other Magnetic Materials29
1.4.5Tables29
1.5Magnetic Nanostructures31
1.5.1Physical Classification of Magnetic Nanostructures32
1.5.2Intrinsic Properties and Finite\|Size Effects34
1.5.3Narrow\|Wall and Constricted\|Wall Phenomena36
1.5.4Nanomagnetic Localization37
1.5.5Cooperative Effects40
1.5.6Random Anisotropy and Remanence Enhancement42
1.5.7Magnetization Dynamics in Nanostructures43
1.5.8Energy\|Barrier Laws47
1.6Conclusions49
Appendix 1.1Magnetic Units50
References50
2Magnetism in Ultrathin Films and Beyond58
2.1Introduction58
2.2Fabrication59
2.2.1Ultrathin Films59
2.2.2Wires61
2.2.3Dots62
2.3Magnetic Properties in Low Dimensional Systems64
2.3.1Metastable Structures64
2.3.2Dimensionality and Phase Transition66
2.3.3Surface/Interface Electronic Structure67
2.3.4Quantum Size Effects69
2.3.5Domains and Domain Walls71
2.4Conclusions74
References743Classical and Quantum Magnetization Reversal Studied in
Nanometer\|Sized Particles and Clusters77
3.1Introduction77
3.2Single\|Particle Measurement Techniques79
3.2.1Overview of Single\|Particle Measurement
Techniques79
3.2.2Micro\|SQUID Magnetometry81
3.3Mechanisms of Magnetization Reversal at Zero Kelvin82
3.3.1Magnetization Reversal by Uniform Rotation
(Stoner\|Wohlfarth Model)82
3.3.2Nonuniform Magnetization Reversal97
3.4Influence of Temperature on the Magnetization Reversal102
3.4.1Néel\|Brown Model of Thermally Activated Magnetization
Reversal102
3.4.2Experimental Methods for the Study of the Néel\|Brown
Model103
3.4.3Experimental Evidence for the Néel\|Brown Model106
3.5Magnetization Reversal by Quantum Tunneling112
3.5.1Quantum Tunneling of Magnetization in Molecular
Clusters113
3.5.2Quantum Tunneling of Magnetization in Individual Single\|
Domain Nanoparticles116
3.5.3Magnetization Measurements of Individual Single\|Domain
Nanoparticles and Wires at Very Low
Temperatures118
3.5.4Quantization of the Magnetization120
3.6Summaries and Conclusions122
References1234Micromagnetic Simulation of Dynamic and Thermal Effects128
4.1Introduction128
4.2Micromagnetic Background129
4.2.1Equation of Motion129
4.2.2Gibbs Free Energy130
4.2.3Langevin Equation131
4.2.4Characteristic Length Scales132
4.3Numerical Techniques133
4.3.1Finite Element Discretization133
4.3.2Magnetostatic Field Calculation134
4.3.3Time Integration135
4.4Numerical Examples137
4.4.1Small Particles137
4.4.2Thin Film Elements140
4.4.3Circular Nanodots140
4.4.4Magnetic Nanowires142
References1455Magnetic Relaxation and Quantum Tunneling of Magnetization147
5.1Introduction147
5.2Magnetic Relaxation and Related Phenomena in Monosized,
Non\|Interacting Particle Systems148
5.2.1Introduction148
5.2.2Blocking Temperature149
5.2.3a.c. Magnetic Susceptibility Measurement150
5.2.4Zero\|Field\|Cooled and Field Cooled Magnetization
Curves155
5.2.5Magnetic Hysteresis Loops158
5.2.6Numerical Simulation Results159
5.3Magnetic Relaxation in Particle Systems with Size Distribution166
5.3.1Introduction166
5.3.2Logarithmic Magnetic Relaxation167
5.4Quantum Tunneling of Magnetization171
5.4.1Introduction171
5.4.2Physics Related to QTM172
5.4.3Observation of QTM in Systems of Nanostructured
Materials175
5.5Conclusions and Future Perspectives177
References1776Nanostructured Exchange\|Coupled Magnets182
6.1Introduction182
6.2Theory of Exchange\|Coupled Magnets184
6.2.1Energy Product184
6.2.2Fundamental Equations186
6.2.3Nucleation Field188
6.2.4Energy Product189
6.2.5Micromagnetic Localization190
6.2.6Texture191
6.2.7Effective Exchange192
6.3Experimental Systems196
6.3.1FePt\|Based Magnets196
6.3.2Rare\|Earth Cobalt Magnets207
6.3.3Nd\|Fe\|B\|Based Magnets220
6.4Conclusions254
References2557High\|Field Investigations on Exchange Coupling in R\|Fe Intermetallics
and Hard/Soft Nanocomposite Magnets267
7.1Introduction267
7.2Exchange and Crystal Field Model for (R, R′)\|Fe\|X
System269
7.3High\|Field Magnetization, Spin Reorientation and
Magnetostriction in (R, R′)2 Fe14B271
7.3.1Magnetic Phase Diagram and Spin Reorientation in
(Er1-xTbx)2Fe14B271
7.3.2Magnetostriction and Spin Reorientation in
(Er1-xTbx)2Fe14B274
7.4Exchange\|Coupling in Hard/Soft Nanocomposite Films278
7.4.1Multilayerd Nd2Fe14B/α\|Fe Films278
7.4.2Nanodispersed Nd2Fe14B/α\|Fe Films284
7.5Conclusions290
References2918Fabrication and Magnetic Properties of Nanometer\|Scale Particle
Arrays294
8.1Introduction294
8.2Fabrication of Regularly Arranged and Shaped Particles
on a Nanometer Scale295
8.2.1Overview295
8.2.2Scanning Tunneling Microscope Assisted Chemical
Vapor Deposition296
8.3Magnetic Measurements on Extremely Small Particles299
8.3.1Overview299
8.3.2Hall Gradiometry301
8.3.3Optimized Hall Measurements for Particle Arrays304
8.3.4Variable Field Magnetic Force Microscopy (MFM) in
Nanoparticles307
8.4Magnetization Processes in Small Particles311
8.4.1Reversible Rotation of Magnetization311
8.4.2Models for Magnetization Reversal without Thermal
Activation316
8.4.3Experimental Results on Magnetization Reversal316
8.4.4Interaction Effects317
8.4.5Comparison to Numerical Simulations320
8.5Thermally Activated Magnetization Reversal in Small Particles322
8.5.1General Considerations322
8.5.2Phenomenological Model323
8.5.3Angular Dependence of Magnetization Reversal327
8.5.4Magnetic Viscosity328
8.6Conclusions331
References3319Processing and Modeling of Novel Nanocrystalline Soft Magnetic
Materials339
9.1Introduction339
9.2Origin of Magnetic Softness—Random Magnetocrystalline
Anisotropy341
9.2.1Magnetic Anisotropies and Magnetic Softness341
9.2.2Random Magnetocrystalline Anisotropy345
9.3Nanostructure\|Magnetic Properties Relationships351
9.3.1Grain Size and Magnetic Softness351
9.3.2Intergranular Phase and Magnetic Coupling357
9.3.3Application\|Oriented Magnetic Properties360
9.4Principles Underlying Alloy Design364
9.4.1Alloying Elements and Alloy Systems364
9.4.2Alloy Design in Fe\|Metal Based Nanocrystalline
Alloys367
9.4.3Alloy Design in Fe\|Metalloid Based Nanocrystalline
Alloys368
9.5Prospects370
References371Index374
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