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عدد المساهمات : 18962 التقييم : 35392 تاريخ التسجيل : 01/07/2009 الدولة : مصر العمل : مدير منتدى هندسة الإنتاج والتصميم الميكانيكى
| موضوع: كتاب Handbook of Advanced Magnetic Materials السبت 10 فبراير 2018, 11:50 pm | |
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أخوانى فى الله أحضرت لكم كتاب Handbook of Advanced Magnetic Materials Volume I: Advanced Magnetic Materials: Nanostructural Effects Edited by: Yi Liu Center for Materials Research and Analysis University of Nebraska Lincoln, Nebraska David J. Sellmyer Center for Materials Research and Analysis University of Nebraska Lincoln, Nebraska Daisuke Shindo Institute of Multidisciplinary Research for Advanced Materials Tohoku University Sendai, Japan Edited by: Yi Liu Center for Materials Research and Analysis University of Nebraska Lincoln, Nebraska David J. Sellmyer Center for Materials Research and Analysis University of Nebraska Lincoln, Nebraska Daisuke Shindo Institute of Multidisciplinary Research for Advanced ~1aterials Tohoku University Sendai, Japan
ويتناول الموضوعات الأتية :
Contents Preface V List of Contributors XVI 1 Intrinsic and Extrinsic Properties of Advanced Magnetic Materials . .. . ... 1 1. 1 Introduction ... ... ... 1 1.2 Intrinsic Properties 3 1. 2. 1 Magnetic Moment 3 1. 2. 2 Exchange'" ... ... ... 4 1. 2. 3 Magnetization and Magnetic Order 6 1. 2. 4 Itinerant Magnetism 8 1. 2.5 Magnetic Anisotropy 10 1. 3 Extrinsic Properties ... ... 14 1. 3. 1 Coherent Rotation 16 1.3.2 Domains and Domain Walls 18 1.3.3 Coercivity 21 1. 4 Magnetic Materials 25 1. 4. 1 Permanent Magnets 25 1. 4. 2 Soft Magnets 27 1. 4.3 Recording Media 28 1. 4.4 Other Magnetic Materials 29 1.4.5 Tables 29 1. 5 Magnetic Nanostructures 31 1. 5. 1 Physical Classification of Magnetic Nanostructures 32 1.5.2 Intrinsic Properties and Finite-Size Effects 34 1. 5.3 Narrow-Wall and Constricted-Wall Phenomena 36 1. 5. 4 Nanomagnetic Localization 37 1. 5. 5 Cooperative Effects ... ... ... 40 1. 5. 6 Random Anisotropy and Remanence Enhancement 42 1. 5. 7 Magnetization Dynamics in Nanostructures 43 1. 5. 8 Energy-Barrier Laws 47 1.6 Conclusions ..·..·..·..·..·..·..·..·..·..·..·..·· ·· ·..·..·· ·..·..· 49 Appendix 1. 1 Magnetic Units 50 References 50 2 Magnetism in Ultrathin Films and Beyond · · 58 2. 1 Introduction ..· 58 2.2 Fabrication 59 Contents Preface V List of Contributors XVI 1 Intrinsic and Extrinsic Properties of Advanced Magnetic Materials ... ... ... 1 1. 1 Introduction " '" 1 1. 2 Intrinsic Properties , 3 1. 2. 1 Magnetic Moment 3 1. 2.2 Exchange'" ... ... ... 4 1. 2. 3 Magnetization and Magnetic Order 6 1. 2.4 Itinerant Magnetism·.. ····.. ··..···.. ·.. · ···.. ··..·..·· 8 1.2.5 Magnetic Anisotropy 10 1. 3 Extrinsic Properties ... ... 14 1. 3. 1 Coherent Rotation 16 1. 3.2 Domains and Domain Walls 18 1.3.3 Coercivity 21 1. 4 Magnetic Materials 25 1. 4. 1 Permanent Magnets 25 1. 4. 2 Soft Magnets 27 1. 4.3 Recording Media 28 1. 4.4 Other Magnetic Materials 29 1.4.5 Tables 29 1. 5 Magnetic Nanostructures 31 1. 5. 1 Physical Classification of Magnetic Nanostructures 32 1.5.2 Intrinsic Properties and Finite-Size Effects 34 1. 5. 3 Narrow-Wall and Constricted-Wall Phenomena 36 1.5.4 Nanomagnetic Localization 37 1. 5. 5 Cooperative Effects 40 1. 5.6 Random Anisotropy and Remanence Enhancement 42 1. 5.7 Magnetization Dynamics in Nanostructures 43 1.5.8 Energy-Barrier Laws 47 1.6 Conclusions ..·... ... ... ... ... 49 Appendix 1. 1 Magnetic Units 50 References 50 2 Magnetism in Ultrathin Films and Beyond 58 2. 1 Introduction ..· 58 2.2 Fabrication ... 59X Contents 2.2. 1 Ultrathin Films 59 2.2.2 Wires 61 2. 2. 3 Dots 62 2.3 Magnetic Properties in Low Dimensional Systems 64 2.3. 1 Metastable Structures 64 2.3.2 Dimensionality and Phase Transition 66 2.3.3 Surface/Interface Electronic Structure 67 2.3.4 Quantum Size Effects 69 2.3.5 Domains and Domain Walls 71 2. 4 Conclusions'" 74 References 74 3 Classical and Quantum Magnetization Reversal Studied in Nanometer-Sized Particles and Clusters 77 3. 1 Introduction ..·.. ··....··....··.. ·.. · ·..·· ·.. ·.. ·..·..·· ·· ·..· 77 3.2 Single-Particle Measurement Techniques 79 3. 2. 1 Overview of Single-Particle Measurement Techniques 79 3.2.2 Micro-SQUID Magnetometry 81 3. 3 Mechanisms of Magnetization Reversal at Zero Kelvin 82 3. 3. 1 Magnetization Reversal by Uniform Rotation (Stoner-Wohlfarth Model) 82 3.3.2 Nonuniform Magnetization Reversal...... 97 3. 4 Influence of Temperature on the Magnetization Reversal 102 3. 4. 1 Neel-Brown Model of Thermally Activated Magnetization Reversal ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 102 3.4.2 Experimental Methods for the Study of the Neel-Brown Model 103 3. 4.3 Experimental Evidence for the Neel-Brown Model 106 3. 5 Magnetization Reversal by Quantum Tunnel ing 112 3. 5. 1 Quantum Tunnel ing of Magnetization in Molecular Clusters ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 113 3.5.2 Quantum Tunneling of Magnetization in Individual SingleDomain Nanoparticles 116 3.5.3 Magnetization Measurements of Individual Single-Domain Nanoparticles and Wires at Very Low Temperatures 118 3. 5.4 Quantization of the Magnetization 120 3.6 Summaries and Conclusions 122 References 123 4 Micromagnetic Simulation of Dynamic and Thermal Effects 128 4. 1 Introduction ... ... ... ... ... ... 128 4.2 Micromagnetic Background 129 X Contents 2. 2. 1 Ultrathin FiIms 59 2.2.2 Wires 61 2. 2. 3 Dots 62 2.3 Magnetic Properties in Low Dimensional Systems 64 2. 3. 1 Metastable Structures ...... ... ... ... ... 64 2. 3.2 Dimensional ity and Phase Transition 66 2.3.3 Surface/Interface Electronic Structure 67 2.3.4 Quantum Size Effects 69 2. 3.5 Domains and Domain Walls 71 2. 4 Conclusions'" 74 References 74 3 Classical and Quantum Magnetization Reversal Studied in Nanometer-Sized Particles and Clusters 77 3. 1 Introduction'" ... ... ... ... ... ... ... ... 77 3.2 Single-Particle Measurement Techniques 79 3.2. 1 Overview of Single-Particle Measurement Techniques 79 3.2.2 Micro-SQUID Magnetometry 81 3.3 Mechanisms of Magnetization Reversal at Zero Kelvin 82 3. 3. 1 Magnetization Reversal by Uniform Rotation (Stoner-Wohlfarth Model) 82 3.3.2 Nonuniform Magnetization Reversal 97 3.4 Influence of Temperature on the Magnetization Reversal 102 3. 4. 1 Neel-Brown Model of Thermally Activated Magnetization Reversal ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 102 3.4.2 Experimental Methods for the Study of the Neel-Brown Model 103 3.4.3 Experimental Evidence for the Neel-Brown Model 106 3. 5 Magnetization Reversal by Quantum Tunnel ing 112 3.5.1 Quantum Tunneling of Magnetization in Molecular Clusters '" 113 3.5.2 Quantum Tunneling of Magnetization in Individual SingleDomain Nanoparticles 116 3.5.3 Magnetization Measurements of Individual Single-Domain Nanoparticles and Wires at Very Low Temperatures 118 3. 5.4 Quantization of the Magnetization 120 3.6 Summaries and Conclusions 122 References ... ... ... ... ... ... ... ... ... 123 4 Micromagnetic Simulation of Dynamic and Thermal Effects 128 4. 1 Introduction ... ... ... ... ... ... 128 4.2 Micromagnetic Background 129Contents XI 4. 2. 1 Equation of Motion 129 4. 2. 2 Gibbs Free Energy 130 4.2. 3 Langevin Equation 131 4.2. 4 Characteristic Length Scales 132 4. 3 Numerical Techniques ... ... ... ... ... ... 133 4.3. 1 Finite Element Discretization 133 4.3.2 Magnetostatic Field Calculation 134 4. 3. 3 Time Integration 135 4.4 Numerical Examples 137 4. 4. 1 Small Particles 137 4.4.2 Thin Film Elements 140 4. 4. 3 Circular Nanodots 140 4.4.4 Magnetic Nanowires 142 References 145 5 Magnetic Relaxation and Quantum Tunneling of Magnetization 147 5. 1 Introduction 147 5. 2 Magnetic Relaxation and Related Phenomena in Monosized, Non-Interacting Particle Systems···..·..···..· · ·· ····..·· 148 5.2. 1 Introduction···... ... ... ... 148 5.2.2 Blocking Temperature'" 149 5.2.3 a.c. Magnetic Susceptibility Measurement 150 5. 2. 4 Zero-Field-Cooled and Field Cooled Magnetization Curves 155 5. 2. 5 Magnetic Hysteresis Loops 158 5.2.6 Numerical Simulation Results 159 5. 3 Magnetic Relaxation in Particle Systems with Size Distribution 166 5. 3. 1 Introduction···... ... ... ... ... ... ... ... 166 5.3.2 Logarithmic Magnetic Relaxation 167 5.4 Quantum Tunneling of Magnetization 171 5. 4. 1 Introduction···... ... ... ... 171 5. 4.2 Physics Related to QTM 172 5. 4. 3 Observation of QTM in Systems of Nanostructured Materials 175 5. 5 Conclusions and Future Perspectives 177 References ... ... ... ... ... ... ... ... ... ... ... ... ... 177 6 Nanostructured Exchange-Coupled Magnets 182 6. 1 Introduction ... ... ... ... ... ... ... ... ... ... 182 6. 2 Theory of Exchange-Coupled Magnets 184 6.2. 1 Energy Product ... ... ... 184 6.2.2 Fundamental Equations 186 6.2.3 Nucleation Field 188 6. 2. 4 Energy Product 189 Contents Xl 4.2. 1 Equation of Motion '" 129 4.2.2 Gibbs Free Energy 130 4. 2.3 Langevin Equation 131 4.2.4 Characteristic Length Scales 132 4.3 NumericalTechniques 133 4. 3. 1 Finite Element Discretization 133 4.3.2 Magnetostatic Field Calculation 134 4. 3. 3 Time Integration 135 4.4 Numerical Examples 137 4. 4. 1 Small Particles 137 4.4.2 Thin Film Elements 140 4. 4. 3 Circular Nanodots 140 4.4.4 Magnetic Nanowires 142 References 145 5 Magnetic Relaxation and Quantum Tunneling of Magnetization 147 5.1 Introduction 147 5. 2 Magnetic Relaxation and Related Phenomena in Monosized, Non-Interacting Particle Systems· ·..· ·..· · · 148 5.2.1 Introduction 148 5.2.2 Blocking Temperature 149 5.2.3 a.c. Magnetic Susceptibility Measurement 150 5.2.4 Zero-Field-Cooled and Field Cooled Magnetization Curves 155 5.2.5 Magnetic Hysteresis Loops 158 5.2.6 Numerical Simulation Results 159 5. 3 Magnetic Relaxation in Particle Systems with Size Distribution 166 5. 3. 1 Introduction'" ... ... ... ... ... ... ... ... 166 5. 3.2 Logarithmic Magnetic Relaxation 167 5.4 Ouantum Tunneling of Magnetization 171 5. 4. 1 Introduction'" ...... ...... 171 5. 4.2 Physics Related to OTM 172 5. 4.3 Observation of OTM in Systems of Nanostructured Materials 175 5. 5 Conclusions and Future Perspectives 177 References ... ... ... ... ... ... ... ... ... ... ... ... ... 177 6 Nanostructured Exchange-Coupled Magnets 182 6. 1 Introduction ... ... ... ... ... ... ... ... ... ... 182 6.2 Theory of Exchange-Coupled Magnets 184 6. 2. 1 Energy Product ... ... ... 184 6.2.2 Fundamental Equations 186 6.2. 3 Nucleation Field 188 6. 2. 4 Energy Product 189XII Contents 6.2.5 Micromagnetic Localization 190 6 . 2 . 6 Texture'" ... ... ... ... 191 6.2. 7 Effective Exchange 192 6. 3 Experimental Systems ... ... 196 6.3. 1 FePt-Based Magnets 196 6. 3.2 Rare-Earth Cobalt Magnets 207 6. 3. 3 Nd-Fe-B-Based Magnets 220 6.4 Conclusions 254 References ... ... ... 255 7 High-Field Investigations on Exchange Coupling in R-Fe Intermetallics and Hard/Soft Nanocomposite Magnets 267 7. 1 Introduction 267 7.2 Exchange and Crystal Field Model for (R, R' )-Fe-X System 269 7.3 High-Field Magnetization, Spin Reorientation and Magnetostriction in (R, R')2 Fe14B 271 7.3. 1 Magnetic Phase Diagram and Spin Reorientation in (Erl-x Tbx)2Fe14B 271 7.3.2 Magnetostriction and Spin Reorientation in (Er,-x Tbx)2Fe,4B 274 7.4 Exchange-Coupling in Hard/Soft Nanocomposite Films 278 7.4. 1 Multilayerd Nd2Fe14 B/ex-Fe Films 278 7.4.2 Nanodispersed Nd2Fe14 B/ex-Fe Films 284 7.5 Conclusions 290 References ... ... ... 291 8 Fabrication and Magnetic Properties of Nanometer-Scale Particle Arrays 294 8. 1 Introduction 0 ••••••• 294 8.2 Fabrication of Regularly Arranged and Shaped Particles on a Nanometer Scale 295 8. 2. 1 Overview'" ... 295 8.2.2 Scanning Tunneling Microscope Assisted Chemical Vapor Deposition 296 8. 3 Magnetic Measurements on Extremely Small Particles 299 8. 3. 1 Overview ..·... ... 299 8. 3.2 Hall Gradiometry 301 8. 3. 3 Optimized Hall Measurements for Particle Arrays 304 8.3.4 Variable Field Magnetic Force Microscopy (MFM) in Nanoparticles 307 8. 4 Magnetization Processes in Small Particles 311 8. 4. 1 Reversible Rotation of Magnetization 311 xn Contents 6.2.5 Micromagnetic Localization 190 6 . 2 . 6 Texture ..·... ... ... ... 191 6. 2. 7 Effective Exchange 192 6. 3 Experimental Systems 196 6. 3. 1 FePt-Based Magnets 196 6. 3.2 Rare-Earth Cobalt Magnets 207 6. 3. 3 Nd-Fe-B-Based Magnets··..···.. · ·..· · 220 6. 4 Conclusions 254 References ... ... ... 255 7 High-Field Investigations on Exchange Coupling in R-Fe Intermetallics and Hard/Soft Nanocomposite Magnets 267 7. 1 Introduction , 267 7.2 Exchange and Crystal Field Model for CR, R')-Fe-X System 269 7.3 High-Field Magnetization, Spin Reorientation and Magnetostriction in CR, R')2 Fe14B 271 7.3. 1 Magnetic Phase Diagram and Spin Reorientation in CEr,-x Tbx)2Fe14B 271 7. 3.2 Magnetostriction and Spin Reorientation in CErl-x Tbx)2Fe14B 274 7.4 Exchange-Coupling in Hard/Soft Nanocomposite Films 278 7.4.1 Multilayerd Nd2Fe14B/a-Fe Films 278 7.4.2 Nanodispersed Nd2Fe14B/a-Fe Films 284 7. 5 Conclusions 290 References " 291 8 Fabrication and Magnetic Properties of Nanometer-Scale Particle Arrays 294 8. 1 Introduction 294 8.2 Fabrication of Regularly Arranged and Shaped Particles on a Nanometer Scale 295 8. 2. 1 Overview .. · , 295 8.2.2 Scanning Tunneling Microscope Assisted Chemical Vapor Deposition 296 8. 3 Magnetic Measurements on Extremely Small Particles 299 8. 3. 1 Overview'" ... ... 299 8. 3.2 Hall Gradiometry 301 8. 3. 3 Optimized Hall Measurements for Particle Arrays 304 8.3.4 Variable Field Magnetic Force Microscopy CMFM) in Nanoparticles 307 8. 4 Magnetization Processes in Small Particles 311 8. 4. 1 Reversible Rotation of Magnetization 311Contents XIII 8.4.2 Models for Magnetization Reversal without Thermal Activation 316 8.4.3 Experimental Results on Magnetization Reversal········· 316 8.4.4 Interaction Effects ... ... ... ... ... ... ... ... 317 8.4.5 Comparison to Numerical Simulations 320 8. 5 Thermally Activated Magnetization Reversal in Small Particles 322 8. 5. 1 General Considerations 322 8. 5.2 Phenomenological Model 323 8. 5. 3 Angular Dependence of Magnetization Reversal 327 8. 5. 4 Magnetic Viscosity 328 8.6 Conclusions 331 References '" 331 9 Processing and Modeling of Novel Nanocrystalline Soft Magnetic Materials 339 9. 1 Introduction 339 9.2 Origin of Magnetic Softness-Random Magnetocrystalline Anisotropy 341 9.2. 1 Magnetic Anisotropies and Magnetic Softness 341 9.2.2 Random Magnetocrystalline Anisotropy 345 9.3 Nanostructure-Magnetic Properties Relationships 351 9. 3. 1 Grain Size and Magnetic Softness ....·..·..· · · 351 9.3.2 Intergranular Phase and Magnetic Coupling 357 9.3.3 Application-Oriented Magnetic Properties 360 9. 4 Principles Underlying Alloy Design 364 9.4. 1 Alloying Elements and Alloy Systems 364 9.4.2 Alloy Design in Fe-Metal Based Nanocrystalline Alloys 367 9.4.3 Alloy Design in Fe-Metalloid Based Nanocrystalline Alloys 368 9. 5 Prospects 370 References ... ... 371 Index 374 Contents xm 8.4.2 Models for Magnetization Reversal without Thermal Activation 316 8. 4. 3 Experimental Results on Magnetization Reversal 316 8.4.4 Interaction Effects ... ... ... ... ...... ...... 317 8. 4.5 Comparison to Numerical Simulations 320 8. 5 Thermally Activated Magnetization Reversal in Small Particles 322 8.5. 1 General Considerations 322 8. 5.2 Phenomenological Model 323 8.5. 3 Angular Dependence of Magnetization Reversal 327 8.5.4 Magnetic Viscosity'" 328 8.6 Conclusions 331 References 331 9 Processing and Modeling of Novel Nanocrystalline Soft Magnetic Materials 339 9. 1 Introduction 339 9.2 Origin of Magnetic Softness-Random Magnetocrystalline Anisotropy 341 9.2. 1 Magnetic Anisotropies and Magnetic Softness 341 9.2.2 Random Magnetocrystalline Anisotropy 345 9.3 Nanostructure-Magnetic Properties Relationships 351 9. 3. 1 Grain Size and Magnetic Softness·.. ··..·..·..· ·······.. 351 9. 3.2 Intergranular Phase and Magnetic Coupling 357 9.3.3 Application-Oriented Magnetic Properties 360 9.4 Principles Underlying Alloy Design 364 9.4. 1 Alloying Elements and Alloy Systems 364 9.4.2 Alloy Design in Fe-Metal Based Nanocrystalline Alloys 367 9.4.3 Alloy Design in Fe-Metalloid Based Nanocrystalline Alloys 368 9. 5 Prospects 370 References ... ... 371 Index 37
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