Novel Functional Magnetic Materials (eBook)

Preface 6
Contents 8
Contributors 10
Chapter 1: Magnetic Shape Memory Materials with Improved Functional Properties: Scientific Aspects 13
1.1 Introduction 13
1.2 Giant Magnetically Induced Deformation of Ferromagnetic SMA 15
1.2.1 Magnetostress as the Origin of Martensite Reorientation 15
1.2.2 Magnetoelastic Coupling as the Origin of Magnetostress 17
1.2.3 Limits of MFIS Observability 21
1.2.4 Ferromagnetic SMAs with Improved Functional Properties 23
1.3 Large Anhysteretic Deformation 25
1.3.1 Problem Statement 25
1.3.2 Crystallographic Aspect of Anhysteretic Deformation 26
1.3.3 Quasi-Second-Order MTs and Giant Quasi-Linear Deformation of SMAs 27
1.3.4 Postcritical Deformational Behavior of Shape Memory Alloy 30
1.3.5 Concluding Remarks 35
1.4 Stability of Deformational Behavior of SMA 36
1.4.1 Problem Statement 36
1.4.2 Internal Stress and Pressure as the Factors of Martensite Stabilization 37
1.4.3 Martensite Destabilization by Thermomechanical Cycling 41
1.5 Influence of Volume Magnetostriction on the Elastic and Transformational Properties of Ferromagnetic SMAs 45
1.5.1 Influence of Volume Magnetostriction on the Elastic Modules of Ferromagnetic SMAs 45
1.5.2 Volume Magnetostriction Contributing to the Heat Evolution During MT 46
1.6 Summary 50
References 51
Chapter 2: Magnetic, Magnetocaloric, Magnetotransport, and Magneto-optical Properties of Ni-Mn-In-Based Heusler Alloys: Bulk, ... 53
2.1 Introduction 54
2.2 Bulk Ni-Mn-In-Based Alloys 55
2.2.1 Sample Fabrication 55
2.2.2 Examples of the Crystal Structure 56
2.2.3 Temperature-Induced Phase Transitions and the Ground State of the Austenitic and Martensitic Phases 57
2.3 Magnetocaloric Effect 60
2.4 Ni-Mn-In-Based Ribbons 63
2.5 Ni-Mn-In-Based Microwires 71
2.6 Magnetotransport Properties 76
2.6.1 Resistivity 76
2.6.2 Magnetoresistance 78
2.6.3 Hall Effect 80
2.7 Magneto-optical Spectra 86
2.8 Conclusions 89
References 90
Chapter 3: Heusler Alloy Ribbons: Structure, Martensitic Transformation, Magnetic Transitions, and Exchange Bias Effect 95
3.1 Introduction: Heusler Alloys - Martensitic Transformation 95
3.2 Heusler Alloy Ribbon Production 97
3.2.1 Arc Melting and Annealing 97
3.2.2 Melt Spinning 98
3.3 Characterization 99
3.3.1 Crystalline Structure (XRD) and Microstructure (SEM-EDX) of Austenitic and Martensitic Phases 99
3.3.2 Calorimetric Characterization of the Martensitic Transformation (DSC) 101
3.3.3 Thermomagnetic Curves and Hysteresis Loops 105
3.4 Martensitic Transformation and Magnetic Transitions 108
3.4.1 Magnetic Field Effect 108
3.4.2 Magnetic Phase Analysis in the Martensite and Austenite Phases 110
3.4.3 Annealing Influence 112
3.5 Exchange Bias Effect: Annealing Influence 116
3.6 Conclusions 120
References 120
Chapter 4: Magnetocaloric Materials 127
4.1 Introduction 127
4.2 Magnetocaloric Effect 129
4.2.1 Thermodynamics of the Magnetocaloric Effect 129
4.2.2 Magnetocaloric Effect at Magnetic Phase Transitions 132
4.2.3 Measurement of the Magnetocaloric Effect 134
4.2.3.1 Latent Heat Determination 134
4.2.3.2 Calculation of the Magnetocaloric Effect from Heat Capacity 140
4.2.3.3 Calculation of the Magnetocaloric Effect from Magnetisation 142
Entropy Change from the Maxwell Relation 142
Entropy Change from the Clausius-Clapeyron Equation 149
Adiabatic Temperature Change from Combined Heat Capacity and Magnetisation Measurements 150
4.2.3.4 Direct Adiabatic Temperature Change Measurement 151
4.3 Magnetic Refrigeration 152
4.4 Technologically Relevant Properties of Magnetocaloric Materials 156
4.4.1 Magnetocaloric Effect 157
4.4.2 Curie Temperature 162
4.4.3 Hysteresis 164
4.4.4 Thermal Transport Properties 168
4.4.5 Mechanical Properties 170
4.4.6 Chemical Stability 172
4.5 Materials 173
4.5.1 Gadolinium 173
4.5.2 Gd5(SixGe1-x)4 Alloys 174
4.5.3 LaFe13-xSix Alloys 178
4.5.4 (Mn,Fe)2(P,X) Compounds 182
4.5.5 Heusler Alloys 185
4.5.6 Manganites 185
4.5.7 Amorphous and Nanocomposite Materials 186
4.5.8 Materials with Transitions Between Magnetically Ordered States 188
4.5.8.1 Fe-Rh Alloys 188
4.5.8.2 Spin Reorientation Transition in Tb2Fe14B and NdCo5 188
4.6 Summary 192
References 193
Chapter 5: Above Room Temperature Ferromagnetism in Dilute Magnetic Oxide Semiconductors 199
5.1 Introduction 200
5.2 Above Room Temperature Ferromagnetism in TiO2-delta:Co 202
5.3 Above Room Temperature Ferromagnetism in TiO2-delta:V 207
5.4 Positron Annihilation Spectroscopy of Defects in TiO2-delta:V(13%) 210
5.4.1 Physics Behind the Experiment 211
5.4.2 Doppler Broadening Spectroscopy (DBS) 212
5.4.3 Experimental Results 214
5.5 Comparison of Magnetic Properties of Co- and V-Doped TiO2-delta Films 217
5.6 Ferromagnetism in ZnO:TM 222
5.7 Conclusions 226
References 227
Chapter 6: Soft Magnetic Wires for Sensor Applications 232
6.1 Introduction 232
6.2 Different Families of Magnetic Wires 234
6.2.1 Magnetic Wires Produced by ``In-Rotating-Water´´ Technique 234
6.2.2 Melt-Extracted Microwires 235
6.2.3 Glass-Coated Microwires 236
6.2.3.1 Chemical and Metallurgical Processes Related with Interaction of the Ingot Alloy and the Glass 238
6.2.3.2 Electromagnetic and Electro-Hydrodynamic Phenomena in the System of Inductor Ingot 238
6.2.3.3 Thermal Conditions of Formation of Cast Microwire 239
6.2.3.4 Parameters of the Casting Process and Their Limits Are the Casting Rate, Diameter of a Microwire, Composition of the M... 239
6.3 Magnetic Properties Relevant for Applications 240
6.3.1 Magnetic Bistability and Domain-Wall Propagation 241
6.3.2 Quasi Non-hysteretic Behavior 257
6.3.3 Matteucci Effect 258
6.3.4 Giant Magnetoimpedance, Stress Impedance, and Torsion Impedance Effects 259
6.4 Conclusions 282
References 283
Chapter 7: Bimagnetic Microwires, Magnetic Properties, and High-Frequency Behavior 289
7.1 Outlook Around Multilayer Microwires 289
7.2 Synthesis of Biphase Magnetic Microwires 291
7.3 The Magnetization Reversal in Bimagnetic Microwires 293
7.3.1 Room Temperature Hysteresis Loops 293
7.3.2 Influence of Layers Thickness 296
7.3.3 Influence of Thermal Treatments 297
7.4 Temperature Dependence of Magnetic Properties 298
7.4.1 Low-Temperature Behavior 298
7.4.2 High-Temperature Behavior 300
7.5 Network Analyzer-Ferromagnetic Resonance in Biphase Magnetic Microwires 301
7.5.1 Effect of Two Phases into the FMR Spectrum 302
7.5.2 Influence of Layers Thickness: The Microwire as a Capacitor 305
7.5.3 Effect of Thermal Treatments: The Influence of the Not-Saturated Phase 306
7.6 Ferromagnetic Resonance Through Cavity-Perturbation Measurements 308
7.6.1 Temperature Dependence of Microwave Properties 309
7.6.2 Room Temperature Analysis: The Role of the Hard-Phase Response 313
7.6.3 Angular Dependence of Microwave Absorption 314
7.7 Final Remarks and Conclusions: Future Perspectives 317
References 318
Chapter 8: Tuneable Metacomposites Based on Functional Fillers 321
8.1 Introduction 321
8.2 Fundamentals to the Design and Fabrication of a Metacomposite 324
8.2.1 Design a Negative Permittivity 325
8.2.2 To Design a Negative Permittivity 328
8.2.3 A Design Example of Double-Negative Metacomposites 330
8.3 Nano-metacomposites with SNG or DNG Characteristics 331
8.3.1 Metacomposites Containing Dielectric Fillers 332
8.3.1.1 ENG Metacomposites 332
8.3.1.2 MNG Metacomposites Containing Dielectric Fillers 335
8.3.2 Metacomposites Containing Magnetic Fillers 336
8.3.2.1 MNG Metacomposites Containing Magnetic Fillers 336
8.3.2.2 DNG Metacomposites 338
8.4 Metacomposites Containing Ferromagnetic Microwires 340
8.5 The Optimisation of Microwire Metacomposites 347
8.5.1 Metacomposites with Orthogonal Microwire Arrays 347
8.5.2 Hybrid Metacomposites 351
8.6 Summary and Outlooks 360
References 362
Chapter 9: Permanent Magnets: History, Current Research, and Outlook 368
9.1 Introduction 368
9.2 Permanent Magnet Physics 373
9.2.1 Energy Considerations 373
9.2.2 Intrinsic Properties 375
9.2.3 Extrinsic Properties and Alnicos 376
9.3 Rare-Earth Free Permanent Magnets 378
9.3.1 Iron-Rich Alloys 378
9.3.2 Co-Rich Alloys 380
9.3.3 L10-Ordered Magnets 381
9.3.4 Manganese Alloys 382
9.4 Nanoscale Permanent Magnetism 383
9.4.1 Geometrical and Optimization 383
9.4.2 Easy-Plane Micromagnetism 388
9.4.3 Curie Temperature Fitting 391
9.4.4 Thermal Excitations and Nanomagnetism 393
9.5 Outlook 396
Appendix: Units in Magnetism 397
References 398
Chapter 10: Bulk Metallic Glasses and Glassy/Crystalline Materials 405
10.1 Introduction 405
10.2 Formation of a Glassy Phase from the Melt 406
10.3 Metallic Glassy Structure 411
10.4 Phase Transformations on Heating and Under Mechanical Exposure 413
10.4.1 Structural Relaxation and Rejuvenation 413
10.4.2 Phase Separation Prior to Crystallization 414
10.4.3 Crystallization of Glassy Alloys 415
10.4.3.1 General Features 415
10.4.3.2 Nanocrystallization 417
10.4.3.3 Formation of Quasicrystals 419
10.5 Mechanical Properties and Deformation Behavior at Room Temperature 421
10.5.1 Bulk Metallic Glasses 421
10.5.2 Glassy-Crystalline Alloys 430
10.6 Magnetic Properties 431
10.7 Corrosion Resistance 437
10.8 Biocompatibility 437
10.9 Applications 438
References 440
ERRATUM TO 449
Index 450