Giant Magnetoresistance (GMR) Sensors (eBook)

Title 2
Giant Magnetoresistance (GMR) Sensors 5
Contents 11
Spintronic Phenomena: Giant Magnetoresistance, Tunnel Magnetoresistance and Spin Transfer Torque 13
1 Giant Magnetoresistance 15
1.1 Short History of GMR 15
1.2 Spin Dependent Transport in Ferromagnetic Transition Metals 17
1.3 Current in Plane GMR 18
1.4 Current Perpendicular to Plane GMR 20
2 Tunnel Magnetoresistance 23
2.1 Amorphous Magnetic Tunnel Junctions 23
2.2 TMR in Crystalline Tunnel Junctions 26
3 Angular Dependence of Transport and Spin Transfer Torque 28
3.1 Transport for Non-collinear Magnetizations Configuration 28
3.2 Spin Transfer Torque 29
4 Conclusion 34
References 35
Microfabrication Techniques 43
1 Introduction 43
2 Deposition Techniques 44
2.1 Physical Vapor Deposition 45
2.2 Chemical Vapor Deposition (CVD) 47
2.3 Electrodeposition 48
3 Patterning 49
3.1 Photolithography 50
3.2 Pattern Transfer Techniques 52
4 Conclusions 55
References 55
Noise in GMR and TMR Sensors 58
1 Noise Formalism 58
1.1 Fluctuations, Average and Distribution 59
1.2 Correlations 60
1.3 Frequency Space and Spectral Density 61
1.4 Sensitivity, Signal to Noise Ratio and Detectivity 63
2 The Different Sources of Noise 64
2.1 Separation of Magnetic and Non Magnetic Noise 64
2.2 Frequency Independent Noise (Thermal or Johnson-Nyquist Noise), Shot Noise 64
2.3 Low Frequency Noise 65
2.4 High Frequency Noise and Ferromagnetic Resonance 68
2.5 External Noise 68
3 Electronics and Noise Measurements 68
3.1 Electronics Design 69
3.2 Additional Remarks and Alternatives 73
4 Noise in Magnetoresistive Sensors 74
4.1 Noise in GMR Devices 74
4.2 Noise in Metallic Magnetic Tunnel Junctions 77
4.3 Noise in Oxide Tunnel Junctions 79
5 Conclusion and Perspectives 79
References 80
Resistive Sensor Interfacing 82
1 Sensors and Electronics 82
2 The Main Parameters of Sensor Electronic Interfaces 87
3 Small Range Resistive Sensor Interfaces 89
4 Wide Range Resistive Sensor Interfaces 96
5 Integrated Microsystems 105
References 110
GMR Based Sensors for IC Current Monitoring 114
1 Introduction 114
2 Fundamentals 116
2.1 Sensing Structures 116
2.2 Sensing Mechanism 118
2.3 Sensing Configurations 120
3 Particular Issues in IC Current Monitoring 122
3.1 Low Signal Level Detection 122
3.2 Bandwidth 125
3.3 Joule Heating 126
4 Current Measurement at the IC Level 128
4.1 Background on Medium Current Applications 129
4.2 Electric Current Monitoring at the IC Level 129
4.3 Power Consumption in ICs 131
4.4 Analogue Isolators 132
4.5 Current-to-Time (I-to-t) Converters 133
5 Monolithic Integration: Trends and Challenges 136
5.1 CMOS 0.35m 137
5.2 CMOS 2.5m 138
6 Conclusions 139
GMR Sensors in Automotive Applications 143
1 Introduction 143
2 GMR Angle Sensing Applications 144
2.1 BLDC Rotor Position Measurement 146
2.2 Steering Angle Application 151
2.3 Angle Error Calibration 153
3 GMR Speed Sensing Applications 157
3.1 Crankshaft Speed and Position Measurement 157
3.2 Wheel Speed Measurement for ABS and ESC Systems 162
3.3 Magnetic Back Bias of GMR Sensors 163
4 Summary 166
References 166
Compass Applications Using Giant Magnetoresistance Sensors (GMR) 167
1 Introduction 167
2 The Earth's Magnetic Field 170
3 Compass Concepts 172
4 GMR Sensor Behavior 175
5 Commercial GMR Compasses 183
6 Discussion 186
7 Conclusions 188
References 188
Commercial Off-The-Shelf GMR Based Sensor on Board Optos Picosatellite 191
1 Introduction – A Flight Opportunity 191
2 Selection of an Appropriate Commercial Off-The-Shelf (COTS) GMR Sensor 194
3 Biasing Mechanism 205
4 Qualification of the Sensor 208
5 Design of the Device 213
6 Performance 214
7 Summary and Conclusions 216
References 218
High-Spatial Resolution Giant Magnetoresistive Sensors – Part I: Application in Non-Destructive Evaluation 221
1 Introduction 221
2 ECT Technique Based Application 222
2.1 Introduction 222
2.2 PCB Inspection Based on ECT Technique 224
2.3 ECT Probe Characteristics and Inspection System 232
2.4 High-Density PCB Inspection 241
3 Conclusions 248
References 249
High-Spatial Resolution Giant Magnetoresistive Sensors – Part II: Application in Biomedicine 252
1 Introduction 252
2 Estimation of Magnetic Fluid Density Inside Tumors 252
2.1 Introduction 252
2.2 Analytical Estimation of Magnetic Fluid Parameters 255
2.3 GMR Needle Probe 260
2.4 Estimation of Magnetic Fluid Weight Density Using the GMR Needle Probe 263
3 Conclusions 278
References 279
Magnetoresistive Sensors for Surface Scanning 283
1 Introduction 283
2 Imaging Sensors Devices: Overview 285
2.1 Flux Sensors 285
2.2 Field Sensors 286
3 Magnetoresistive Sensors in Imaging and Scanning Microscopy 287
3.1 Arrays of Individual MR Sensors 289
3.2 Gradiometer Configuration 290
3.3 Cantilever MR Probes 290
3.4 Comparison of MR Sensors 292
4 Magnetoresistive Microscopy for Die Level Fault 292
4.1 Sensitivity 295
4.2 Resolution and Sensor Geometry 298
5 Conclusion 301
References 302
Author Index 308