Superconductivity: Fundamentals and Applications, 2nd, Revised and Enlarged Edition

Introduction 1

1 Fundamental Properties of Superconductors 11

1.1 The Vanishing of the Electrical Resistance 11

1.2 Ideal Diamagnetism, Flux Lines, and Flux Quantization 21

1.3 Flux Quantization in a Superconducting Ring 28

1.4 Superconductivity: A Macroscopic Quantum Phenomenon 31

1.5 Quantum Interference 43

1.5.1 Josephson Currents 44

1.5.2 Quantum Interference in a Magnetic Field 57

2 Superconducting Elements, Alloys, and Compounds 73

2.1 Conventional and Unconventional Superconductors 73

2.2 Superconducting Elements 76

2.3 Superconducting Alloys and Metallic Compounds 81

2.3.1 The b-Tungsten Structure 81

2.3.2 Magnesium Diboride 83

2.3.3 Metal-Hydrogen Systems 84

2.4 Fullerides 85

2.5 Chevrel Phases and Boron Carbides 87

2.6 Heavy-Fermion Superconductors 90

2.7 Natural and Artificial Layered Superconductors 91

2.8 The Superconducting Oxides 93

2.8.1 Cuprates 94

2.8.2 Bismuthates, Ruthenates, and Other Oxide Superconductors 100

2.9 Organic Superconductors 101

2.10 Superconductivity Due to the Field Effect 104

3 Cooper Pairing 111

3.1 Conventional Superconductivity 111

3.1.1 Cooper Pairing by Means of Electron-Phonon Interaction 111

3.1.2 The Superconducting State, Quasiparticles, and BCS Theory 118

3.1.3 Experimental Confirmation of Fundamental Concepts About the Superconducting State 123

3.1.3.1 The Isotope Effect 123

3.1.3.2 The Energy Gap 126

3.1.4 Special Properties of Conventional Superconductors 142

3.1.4.1 Influence of Lattice Defects on Conventional Cooper Pairing 142

3.1.4.2 Influence of Paramagnetic Ions on Conventional Cooper Pairing 149

3.2 Unconventional Superconductivity 155

3.2.1 General Aspects 155

3.2.2 High-Temperature Superconductors 161

3.2.3 Heavy Fermions, Ruthenates, and Other Unconventional Superconductors 178

4 Thermodynamics and Thermal Properties of the Superconducting State 189

4.1 General Aspects of Thermodynamics 189

4.2 Specific Heat 193

4.3 Thermal Conductivity 197

4.4 Ginzburg-Landau Theory 200

4.5 Characteristic Lengths of Ginzburg-Landau Theory 204

4.6 Type-I Superconductors in a Magnetic Field 209

4.6.1 Critical Field and Magnetization of Rod-Shaped Samples 210

4.6.2 Thermodynamics of the Meissner State 214

4.6.3 Critical Magnetic Field of Thin Films in a Field Parallel to the Surface 218

4.6.4 The Intermediate State 219

4.6.5 The Wall Energy 224

4.6.6 Influence of Pressure on the Superconducting State 227

4.7 Type-II Superconductors in a Magnetic Field 232

4.7.1 Magnetization Curve and Critical Fields 233

4.7.2 The Shubnikov Phase 243

4.8 Fluctuations Above the Transition Temperature 254

4.9 States Outside Thermodynamic Equilibrium 259

5 Critical Currents in Type-I and Type-II Superconductors 269

5.1 Limit of the Supercurrent Due to Pair Breaking 269

5.2 Type-I Superconductors 271

5.3 Type-II Superconductors 277

5.3.1 Ideal Type-II Superconductor 277

5.3.2 Hard Superconductors 282

5.3.2.1 Pinning of Flux Lines 282

5.3.2.2 Magnetization Curve of Hard Superconductors 286

5.3.2.3 Critical Currents and Current-Voltage Characteristics 295

6 Josephson Junctions and Their Properties 305

6.1 Current Transport Across Interfaces in a Superconductor 305

6.1.1 Superconductor-Insulator Interface 305

6.1.2 Superconductor-Normal Conductor Interfaces 312

6.2 The RCSJ Model 319

6.3 Josephson Junctions Under Microwave Irradiation 324

6.4 Vortices in Long Josephson Junctions 327

6.5 Quantum Properties of Superconducting Tunnel Junctions 339

6.5.1 Coulomb Blockade and Single-Electron Tunneling 339

6.5.2 Flux Quanta and Macroscopic Quantum Coherence 345

7 Applications of Superconductivity 351

7.1 Superconducting Magnetic Coils 352

7.1.1 General Aspects 352

7.1.2 Superconducting Cables and Tapes 353

7.1.3 Coil Protection 362

7.2 Superconducting Permanent Magnets 364

7.3 Applications of Superconducting Magnets 367

7.3.1 Nuclear Magnetic Resonance 367

7.3.2 Magnetic Resonance Imaging 371

7.3.3 Particle Accelerators 372

7.3.4 Nuclear Fusion 374

7.3.5 Energy Storage Devices 376

7.3.6 Motors and Generators 377

7.3.7 Magnetic Separation 378

7.3.8 Levitated Trains 379

7.4 Superconductors for Power Transmission: Cables, Transformers, and Current-Limiting Devices 380

7.4.1 Superconducting Cables 381

7.4.2 Transformers 383

7.4.3 Current-Limiting Devices 383

7.5 Superconducting Resonators and Filters 384

7.5.1 High-Frequency Behavior of Superconductors 385

7.5.2 Resonators for Particle Accelerators 388

7.5.3 Resonators and Filters for Communications Technology 391

7.6 Superconducting Detectors 396

7.6.1 Sensitivity, Thermal Noise, and Environmental Noise 397

7.6.2 Incoherent Radiation and Particle Detection: Bolometers and Calorimeters 398

7.6.3 Coherent Detection and Generation of Radiation: Mixers, Local Oscillators, and Integrated Receivers 402

7.6.4 Quantum Interferometers as Magnetic Field Sensors 409

7.6.4.1 SQUID Magnetometer: Basic Concepts 409

7.6.4.2 Environmental Noise, Gradiometers, and Shielding 420

7.6.4.3 Applications of SQUIDs 423

7.7 Superconductors in Microelectronics 427

7.7.1 Voltage Standards 427

7.7.2 Digital Electronics Based on Josephson Junctions 431

References 435

Monographs and Collections 443

Outlook 447

Subject Index 453