Preface ........................................................ ix
Author ......................................................... xi
Units, Symbols, and Constants Used in This Book .............. xiii
1 Introduction to Magnetic Measurements ........................ 1
2 Fundamentals of Magnetic Measurements ........................ 5
2.1 Historical Background ................................... 5
2.2 Main Terms .............................................. 6
2.2.1 Magnetic Field Strength H, Magnetic Flux Ф,
and Magnetic Flux Density В ...................... 6
2.2.2 Magnetization M .................................. 8
2.2.3 Magnetic Polarization J .......................... 8
2.2.4 Permeability μ ................................... 8
2.2.5 Susceptibility χ ................................ 10
2.2.6 Reluctance R .................................... 10
2.3 The Magnetization Process of Ferromagnetic Materials ... 10
2.3.1 Domain Structure ................................ 10
2.3.2 Magnetization Curve ............................. 11
2.3.3 Hysteresis Loop ................................. 12
2.4 Anisotropy and Texture ................................. 13
2.4.1 Magnetocrystalline Anisotropy ................... 13
2.4.2 Texture ......................................... 16
2.4.3 Shape Anisotropy ................................ 17
2.5 Electromagnetic Loss ................................... 19
2.5.1 Axial Magnetization Power Loss .................. 19
2.5.2 Power Loss under Rotational Magnetization ....... 21
2.6 Influence of the Magnetic Field on Physical
Properties of a Material ............................... 23
2.6.1 Magnetostriction and Other Magnetoelastic
Effects ......................................... 23
2.6.2 Magnetoresistance ............................... 25
2.6.3 Magneto-Optical Phenomena ....................... 28
2.6.4 Magnetocaloric Effect ........................... 30
2.7 Magnetic Resonance ..................................... 30
2.7.1 Gyromagnetic Ratio and Larmor Precession ........ 30
2.7.2 Nuclear Magnetic Resonance ...................... 32
2.7.3 Electron Spin Resonance ......................... 34
2.7.4 Ferromagnetic Resonance ......................... 35
2.7.5 Overhauser Resonance ............................ 36
2.7.6 Mossbauer Resonance ............................. 37
2.8 Superconductivity Used in Magnetic Measurements ........ 38
2.8.1 Superconductivity and Magnetism—The Meissner
Effect .......................................... 38
2.8.2 Josephson Effect ................................ 38
2.8.3 The SQUID Devices ............................... 40
2.8.4 Quantum Hall Effect ............................. 41
2.9 Main Rules of Magnetics ................................ 42
2.9.1 The Biot-Savart Law ............................. 42
2.9.2 Ampere's Circuital Law .......................... 43
2.9.3 Faraday's Law of Induction ...................... 44
2.9.4 Lorentz Force ................................... 45
2.9.5 Poynting's Vector ............................... 46
2.9.6 Maxwell's Equations ............................. 47
2.9.7 Computation of a Magnetic Field ................. 48
2.10 Physical Principles of Magnetism ....................... 51
2.10.1 Magnetic Field and the Magnetic Moment .......... 51
2.10.2 Magnetic Field and Band Structure Density of
States .......................................... 53
2.10.3 Weak Magnetism—Diamagnetism and Paramagnetism ... 57
2.10.4 Strong Magnetism—Ferromagnetism ................. 60
2.10.5 Mixed Magnetism—Antiferromagnetism and
Ferrimagnetism .................................. 62
2.10.6 Amorphous and Nanocrystalline Materials ......... 65
2.10.7 Magnetic Domains and Domain Walls ............... 66
2.11 Magnetic Hysteresis .................................... 71
2.11.1 Magnetization Process ........................... 71
2.11.2 Rayleigh Model of Hysteresis .................... 76
2.11.3 Stoner-Wohlfart Model of Hysteresis ............. 78
2.11.4 Preisach Model of Hysteresis .................... 80
2.11.5 Jiles-Atherton Model of Hysteresis .............. 83
2.11.6 Approximation of the Magnetizing Curve and
Hysteresis ...................................... 84
2.12 Sources of a Magnetic Field ............................ 85
2.12.1 Helmholtz Coil .................................. 85
2.12.2 Long Solenoid ................................... 87
2.12.3 Sources of High Magnetic Field .................. 88
2.12.4 Sources of a Magnetic Field with Arbitrary
Waveform ........................................ 91
2.13 Samples and Circuits of the Material under Test ........ 93
2.13.1 Measurements of В and H Values .................. 93
2.13.2 Ring Core ....................................... 95
2.13.3 Epstein Frame ................................... 97
2.13.4 Single Sheet and Single Strip Testers ........... 99
2.13.5 Samples for Two-Dimensional Measurements ....... 102
2.13.6 Open Samples ................................... 104
2.14 Magnetic Shielding .................................... 105
2.14.1 Magnetic Field Pollution ....................... 105
2.14.2 Magnetic Shielding ............................. 106
2.14.3 Active Magnetic Shielding—Magnetic Field
Cancelling ..................................... 107
2.14.4 Magnetically Shielded Room ..................... 108
References ................................................. 109
3 Magnetic Materials ......................................... 117
3.1 Soft Magnetic Materials: General Information .......... 117
3.1.1 Properties and Classification .................. 117
3.1.2 Pure Iron ...................................... 118
3.2 Silicon Iron Electrical Steel ......................... 121
3.2.1 Conventional Grain-Oriented SiFe Steel ......... 121
3.2.2 HiB Grain-Oriented Electrical Steel ............ 123
3.2.3 SiFe Non-Oriented Electrical Steel ............. 126
3.2.4 Unconventional Iron-Based Alloys ............... 129
3.3 Nickel- and Cobalt-Based Alloys ....................... 131
3.3.1 NiFe Alloys (Permalloy) ........................ 131
3.3.2 CoFe and CoFeNi Alloys (Permendur and
Perminvar) ..................................... 134
3.4 Amorphous and Nanocrystalline Alloys .................. 135
3.4.1 Amorphous Soft Magnetic Materials (Metallic
Glass) ......................................... 135
3.4.2 Nanocrystalline Soft Magnetic Materials ........ 137
3.5 Soft Ferrites ......................................... 140
3.5.1 MnZn and NiZn Ferrites ......................... 140
3.5.2 Ferrites for Microwave Applications ............ 141
3.6 Hard Magnetic Materials ............................... 142
3.6.1 General Remarks ................................ 142
3.6.2 Alnico Alloys .................................. 146
3.6.3 Hard Magnetic Ferrites ......................... 146
3.6.4 Rare Earth Hard Magnetic Materials ............. 147
3.7 Special Magnetic Materials .......................... 149
3.7.1 Thin Magnetic Films ............................ 149
3.7.2 Ferrofluids and Magnetorheological Liquids ..... 155
References ................................................. 155
4 Magnetic Sensors ........................................... 159
4.1 General Remarks ....................................... 159
4.1.1 Magnetic Field Sensors—Classification .......... 159
4.1.2 Specification of the Performances of Magnetic
Sensors ........................................ 159
4.2 Induction Sensors ..................................... 164
4.2.1 Introduction ................................... 164
4.2.2 Air Coils versus Ferromagnetic Core Coils ...... 165
4.2.3 Design of the Air Coil Sensor .................. 165
4.2.4 Design of Ferromagnetic Core Coil Sensor ....... 167
4.2.5 Frequency Response of Search Coil Sensor ....... 169
4.2.6 Electronic Circuits Connected to the Coil
Sensor ......................................... 170
4.2.7 Moving Coil Sensor ............................. 172
4.2.8 Gradiometer Sensor ............................. 172
4.2.9 Rogowski Coil .................................. 174
4.2.10 Other Induction Sensors ........................ 175
4.2.10.1 Flux Ball Sensor ...................... 175
4.2.10.2 Tangential Field Sensor (H-Coil
Sensor) ............................... 175
4.2.10.3 Needle Sensors (B-Coil Sensors) ....... 176
4.2.11 Coil Sensor Used as a Magnetic Antenna ......... 177
4.3 Fluxgate Sensor ....................................... 179
4.3.1 Principle of Operation ......................... 179
4.3.2 Performances of Fluxgate Sensors ............... 182
4.3.3 Design of Fluxgate Sensors ..................... 183
4.3.4 Multicomponent Sensor Systems (Compass,
Gradiometer) ................................... 185
4.3.5 Electronic Circuits of Fluxgate Sensors ........ 186
4.4 Magnetoresistive and Magnetoimpedance Sensors ......... 189
4.4.1 Magnetoresistance—General Remarks .............. 189
4.4.2 AMR Magnetic Field Sensors ..................... 191
4.4.3 Multilayer GMR Magnetic Field Sensors .......... 197
4.4.4 Spin-Valve GMR Magnetic Field Sensors .......... 200
4.4.5 Spin-Dependent Tunneling GMR Magnetic Field
Sensors ........................................ 204
4.4.6 Giant Magnetoimpedance Sensors ................. 207
4.5 Hall-Effect Sensors ................................... 213
4.5.1 Physical Principles of the Hall Effect ......... 213
4.5.2 Design of Hall Sensors ......................... 214
4.5.3 Performance of the Hall Sensors ................ 216
4.5.4 Integrated Circuit Hall Sensors ................ 218
4.5.5 Hall-Effect-Based Semiconductor
Magnetoresistors ............................... 218
4.6 SQUID Sensors ......................................... 221
4.6.1 Operating Principle of SQUID Sensors ........... 221
4.6.2 Design and Properties of SQUID Sensors ......... 223
4.6.3 SQUID Magnetometers ............................ 226
4.7 Resonance Sensors and Magnetometers ................... 228
4.7.1 General Remarks ................................ 228
4.7.2 NMR Magnetometers for Measurements of Strong
Magnetic Fields ................................ 229
4.7.3 NMR Magnetometers for Measurements of Weak
Magnetic Fields ................................ 232
4.7.4 Optically Pumped Sensors and Magnetometers ..... 235
4.7.5 Overhauser Magnetometers ....................... 238
4.8 Other Magnetic Sensors .............................. 240
4.8.1 Magnetoelastk and Wiegand-Effect Sensors ....... 240
4.8.2 Other and New Principles ....................... 242
References ................................................. 244
5 Testing of Magnetic Materials .............................. 257
5.1 AC Testing of Soft Magnetic Materials ................. 257
5.1.1 What Do We Usually Test? ....................... 257
5.1.2 Standard Tests of Soft Magnetic Materials ...... 261
5.1.3 Single-Sheet and Single-Strip Testers .......... 264
5.1.4 Online Testing Devices ......................... 266
5.1.5 Medium- and High-Frequency Testing of
Magnetic Materials ............................. 268
5.1.6 Local Measurements of the Parameters of
Magnetic Materials ............................. 271
5.1.7 Rotational Power Loss .......................... 280
5.1.8 Two-Dimensional Properties ..................... 283
5.1.9 Anisotropy and Texture ......................... 286
5.2 DC Testing of Soft Magnetic Materials ................. 294
5.2.1 Analog and Digital Fluxmeters .................. 294
5.2.2 Point-by-Point DC Testing of Soft Magnetic
Materials ...................................... 298
5.2.3 Continuous Quasi-Static Testing of Soft
Magnetic Materials ............................. 300
5.2.4 Permeameters for Testing of Soft Magnetic
Materials ...................................... 301
5.3 Testing of Hard Magnetic Materials .................... 302
5.3.1 Testing of the Hard Magnetic Materials in
Closed Magnetic Circuit ........................ 302
5.3.2 Testing of the Hard Magnetic in Open Magnetic
Circuit ........................................ 303
5.3.3 Pulsed Field Methods ........................... 306
5.4 Special Methods of Testing of Magnetic Materials ...... 307
5.4.1 Magnetometric Methods .......................... 307
5.4.2 Magnetovision Method ........................... 310
5.4.3 Other Scanning Systems ......................... 316
5.4.4 Investigations of the Magnetostriction and
Other Magnetomechanical Effects ................ 319
References ................................................. 325
6 Magnetic Field Measurements and Their Applications ......... 335
6.1 Environment Magnetic Fields ........................... 335
6.1.1 Earth's Magnetic Fields ........................ 335
6.1.2 The Space Resea rch ............................ 338
6.1.3 Magnetic Exploration and Surveying ............. 341
6.1.4 Compasses and Navigation ....................... 346
6.1.5 Electromagnetic Pollution ...................... 347
6.2 Applications of Magnetic Field Measurements ........... 351
6.2.1 Detection of Magnetic Objects: Magnetic
Signature ...................................... 351
6.2.2 Mechanical Transducers ......................... 354
6.2.3 Electrical Transducers ......................... 359
6.3 Magnetic Diagnostics .................................. 363
6.3.1 Magnetic Imaging ............................... 363
6.3.2 Magnetic Nondestructive Testing ................ 369
6.3.3 Magnetism in Medicine .......................... 373
References ................................................. 379
Index ......................................................... 383
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