The Physical Principles of Magneto-optical Recording

Frontmatter......Page 1
Contents......Page 7
Preface......Page 15
Introduction......Page 21
1.1. Preliminaries and Basic Definitions......Page 23
1.2. Organization of Data on the Disk......Page 30
1.3. The Optical Path......Page 37
1.4. Automatic Focusing......Page 47
1.5. Automatic Tracking......Page 49
1.6. The Thermomagnetic Recording Process......Page 53
1.7. Magneto-optical Readout......Page 59
1.8. Materials used in Magneto-optical Recording......Page 65
1.9. Recent Developments......Page 70
Problems......Page 75
2.1. Definitions and Basic Properties......Page 78
2.2. Gaussian-beam Propagation in Free Space......Page 82
2.3. The Circle Diagram......Page 84
2.4. Effect of Lens on Gaussian Beam......Page 87
Problems......Page 92
Introduction......Page 97
3.1. Stationary-phase Approximation......Page 98
3.2. Application of Stationary-phase Method to Diffraction Problems......Page 99
3.3. Near-field and Far-field Diffraction......Page 102
3.4. Diffraction in the Presence of a Lens......Page 110
3.5. Vector Effects in Diffraction......Page 113
Problems......Page 124
4.1. Formulation of the Problem......Page 127
4.2. Diffraction from Knife-edge......Page 131
4.3. Diffraction from 180° Phase-step......Page 135
4.4. Diffraction from 90° Phase-step......Page 136
4.5. Detecting Phase-steps by Spatial Matched Filtering......Page 138
Problems......Page 146
Introduction......Page 148
5.1. Notation and Formalism......Page 150
5.2. Maxwell's Equations and Plane-wave Propagation......Page 152
5.3. Plane Wave in an Isotropic Medium......Page 154
5.4. Reflection at the Interface of Free Space and an Isotropic Medium......Page 158
5.5. Reflection at the Interface of Free Space and a Birefringent Medium......Page 162
5.6. Reflection at the Interface of Free Space and a Magnetic Medium; the Magneto-optical Kerr Effect......Page 167
5.7. Plane Wave in Medium with Arbitrary Dielectric Tensor......Page 172
5.8. Boundary Conditions at the Interface between Adjacent Layers; Iterative Formula for Computing the Reflectivity of Multilayers......Page 176
5.9. Plane-wave Transmission Through Multilayers......Page 179
5.11. Numerical Results......Page 181
Appendix 5.A. Transformation of Dielectric Tensor under Rotation of Coordinates......Page 190
Appendix 5.B. Method of Computing the Roots of Fourth-order Polynomials......Page 192
Problems......Page 194
6.1. States of Circular, Linear, and Elliptical Polarization......Page 200
6.2. Quarter-wave Plate (QWP)......Page 203
6.3. Polarizing Beam-splitter (PBS)......Page 206
6.4. Differential Detection Scheme and Magneto-optical Readout......Page 207
6.5. Wavelength-dependence of Polar Magneto-optical Kerr Effect......Page 213
6.6. Edge Detection using Diffraction from Domain Walls......Page 220
6.7. Figure of Merit for Magneto-optical Media......Page 226
Problems......Page 232
7.1. Focused Beams, Oblique Rays, and Polarization Conversion......Page 234
7.2. Numerical Analysis......Page 237
7.3. Summary and Conclusions......Page 264
Problems......Page 266
Introduction......Page 269
8.1. Collimation and Focusing of the Laser Diode Beam......Page 272
8.2. Diffraction Gratings and Grooved Optical Disks......Page 273
8.3. Analysis of Focus-error Detection by the Astigmatic Method......Page 284
8.4. Analysis of Focus-error Detection by a Ring-Toric Lens......Page 297
8.5. Diffraction Effects in Magneto-optical Readout......Page 302
Problems......Page 311
Introduction......Page 315
9.1. Noise in the Electronic Circuitry......Page 318
9.2. Shot Noise in Photodetection......Page 319
9.3. Laser Noise......Page 327
9.4. Noise due to Disk Reflectivity Fluctuations and Depolarization......Page 331
9.5. Jitter and Signal-amplitude Fluctuations......Page 340
Problems......Page 348
Introduction......Page 349
10.1. Preliminary Remarks......Page 350
10.2. The State-transition Table......Page 353
10.3. The Trellis Diagram......Page 354
10.4. Encoding and Decoding Algorithms......Page 358
10.5. Burst-error Correction......Page 360
10.6. Viterbi Decoding......Page 362
10.7. Random-error Correction......Page 363
10.8. Numerical Results and Discussion......Page 364
10.9. Concluding Remarks......Page 366
Problems......Page 369
Introduction......Page 370
11.1. The Heat Diffusion Equation......Page 371
11.2. Numerical Solution of the Heat Diffusion Equation......Page 385
11.3. Light Absorption and Heat Diffusion in Multilayers......Page 391
Problems......Page 411
Introduction......Page 412
12.1. Magnetic Fields in Free Space......Page 413
12.2. Current Loops and the Magnetic Dipole Moment......Page 420
12.3. Larmor Diamagnetism......Page 433
12.4. Ground State of Atoms with Partially Filled Shells -- Hund's Rules......Page 437
12.5. Paramagnetism......Page 440
12.6. Exchange Interaction......Page 453
12.7. Magnetic Order......Page 460
12.8. Electronic Structure and Magnetic Properties of the Rare Earths......Page 469
12.9. Transition Metals of the Iron Group......Page 476
12.10. Magnetic Anisotropy......Page 480
Problems......Page 487
Introduction......Page 489
13.1. Domain Walls in Perpendicular Films......Page 493
13.2. Mathematical Analysis of Stray and Demagnetizing Fields......Page 498
13.3. Micromagnetics of Circular Domains......Page 515
13.4. Measurement of the Energy Density of Domain Walls......Page 529
Problems......Page 533
Introduction......Page 535
14.1. The Mean-field Model......Page 537
14.2. Comparison with Experiment......Page 542
14.3. Single-ion Anisotropy and the Mean-field Model......Page 552
14.4. Exchange Stiffness Coefficient......Page 553
14.5. Macroscopic Anisotropy Energy Constant......Page 554
14.6. Domain Wall Characteristics......Page 558
14.7. Concluding Remarks......Page 559
Problems......Page 561
Introduction......Page 563
15.1. Magnetization Dynamics for a Lattice of Interacting Dipoles......Page 564
15.2. Domain Wall Structure and Dynamics; Analytic Treatment......Page 574
15.3. Computer Simulations......Page 586
Problems......Page 605
Introduction......Page 606
16.1. The Stoner -- Wohlfarth Theory of Magnetization Reversal......Page 608
16.2. Nucleation Coercivity......Page 614
16.3. Coercivity of Domain Wall Motion......Page 626
16.4. Concluding Remarks......Page 654
Problems......Page 656
Introduction......Page 658
17.1. Facts and Observed Phenomena......Page 659
17.2. Magnetostatic Model of the Recording Process......Page 667
17.3. Dynamic Simulation of the Recording Process......Page 672
17.4. Exchange-coupled Magnetic Multilayers......Page 687
Problems......Page 697
Introduction......Page 698
18.1. Magnetic, Magneto-optical and Galvanomagnetic Measurements......Page 700
18.2. Polarized-light Microscopy......Page 713
18.3. Lorentz Electron Microscopy......Page 721
18.4. Magnetic Force Microscopy (MFM)......Page 732
Problems......Page 744
References......Page 745
Index......Page 767