The popularity of the First Edition of this book has been very gratifying. It confirms that there is a genuine need for a text covering the magnetic bubble technology. We are pleased that the readers have found that this book satisfies that need. It has been used as a text for courses in both universities and industry, and as a reference manual by workers active in the field. To meet the need for more copies of the book it seemed preferable to publish a second edition rather than merely a second printing. There has been some significant progress, even in the short time since the initial printing, and we wanted to include that. At the same time we would like to provide the new copies at the lowest possible cost so that they are more easily obtained by students. For this reason the new edition is in soft cover and the recent progress has been described in a final chapter rather than incorporated into the original chapters. This eliminates the expense of resetting and repaging the original text. At the same time up-to-date references have been added and typographical errors have been corrected in the original chapters. It is our hope that this edition will be useful to those with an interest in the fascinating field of magnetic bubbles.

Inhalt

1. Introduction to Magnetic Bubbles.- 1.1 What Are Magnetic Bubbles?.- 1.2 Available Bubble Materials.- 1.3 How Can Bubbles be Manipulated?.- 1.4 Why Are Bubbles of Practical Interest?.- 1.5 A Typical Storage Device.- 1.6 Why Are Bubbles of Scientific Interest?.- 1.7 Scope and Organization of the Book.- 1.8 History.- 1.9 Summary.- 2. Static Properties of Magnetic Bubbles.- 2.1 Fundamental Characteristics of the Bubble Film.- 2.1.1 Magnetic Interactions.- a) Exchange Energy Density, Ex.- b) Demagnetization Energy Density, ED.- c) Anisotropy Energy Density, EK.- d) Magnetic Field Energy Density, EH.- e) Magnetoelastic Energy Density, ES.- 2.1.2 Structural Characteristics of the Bubble Film.- 2.1.3 Anisotropy Energy Density.- a) Growth Anisotropy Density, EKG.- b) Crystalline Anisotropy Energy Density, EKC.- 2.1.4 Summary of Important Film Parameters.- 2.2 Bubble Domain Configurations.- 2.2.1 Equilibrium Configuration of a Small Segment of Domain Wall.- 2.2.2 Equilibrium Configuration of an Isolated Bubble.- 2.2.3 Influence of Permalloy Overlayers.- 2.2.4 Equilibrium Configuration of a Bubble Lattice.- 2.2.5 Bubble States.- 2.2.6 Hard Bubbles.- 2.3 Summary.- 3. Dynamic Properties of Magnetic Bubbles.- 3.1 Motion of a Wall.- 3.1.1 Description of Planar Wall Segments.- 3.1.2 Motion of an Uncoupled Magnetic Moment.- 3.1.3 Equation of Motion for a Planar Domain Wall Segment.- 3.1.4 Motion of an Infinite Planar Wall Without Bloch Lines.- 3.1.5 Motion of a Planar Wall Without Bloch Lines in a Film of Thickness, h.- 3.1.6 Motion of a Bloch Line in a Moving Bloch Wall.- 3.1.7 Summary of the Motion of Planar Walls.- 3.2 Motion of a Bubble.- 3.2.1 Bubble Mobility.- 3.2.2 Gyrotropic Bubble Deflection.- 3.2.3 Response of Bloch Lines to Bubble Motion.- 3.2.4 The Influence of the Film Surface.- 3.2.5 Bloch Line Phenomena.- 3.2.6 Influence of a Surface Cap.- 3.2.7 Influence of Orthorhombic Anisotropy.- 3.3 Summary.- 4. Basic Permalloy-Bar Bubble Devices.- 4.1 Propagation.- 4.1.1 TI Bar Propagation Model.- 4.1.2 TI Bar Propagation Margins.- 4.1.3 C Bar Propagation Margins.- 4.1.4 Failure Mechanisms in C Bar Propagation.- 4.2 Other Functional Elements.- 4.2.1 Generators.- 4.2.2 Switches.- 4.2.3 Sensors.- 4.3 Total Chip Performance.- 4.4 Device Scaling.- 4.5 Summary.- 5. Other Bubble Device Forms.- 5.1 Two-Level Permalloy Bar.- 5.2 Charged-Wall Bubble Devices.- 5.2.1 CD Propagation.- 5.2.2 Propagation on Ion-Implanted CD Patterns.- 5.2.3 The Influence of Anisotropy in the Implanted Layer.- 5.2.4 The Influence of Pattern Geometry.- 5.2.5 Other CD Device Functions.- 5.3 Bubble Lattice Devices.- 5.3.1 Review of Salient Features of Lattice Bubbles.- 5.3.2 Lattice Propagation.- 5.3.3 Other Lattice Functions.- 5.4 Current Sheet Devices.- 5.4.1 Dual Conductor (DC).- 5.4.2 Cross-Hatch (XH).- 5.5 Summary.- 6. Bubble Materials.- 6.1 The General Approach to Tailoring the Properties of Bubble Materials.- 6.2 Garnets.- 6.2.1 Crystal Structure and Lattice Spacing.- 6.2.2 Magnetization.- 6.2.3 Magnetic Anisotropy.- 6.2.4 Garnet Dodecahedral Sites.- 6.2.5 Dynamic Properties.- 6.2.6 Range of Garnet Properties.- 6.3 Hexaferrites.- 6.3.1 Crystal Structure.- 6.3.2 Magnetic Properties.- 6.4 Amorphous Materials.- 6.4.1 Similarities and Differences.- 6.4.2 Static Properties.- 6.4.3 Dynamic Properties.- 6.4.4 Summary.- 6.5 Orthoferrites.- 6.6 Summary.- 7. Device Chip Fabrication.- 7.1 Crystal Growth.- 7.1.1 Choice of Substrates.- 7.1.2 Czochralski Growth of Garnet Crystals.- 7.1.3 Critical Factors and Typical Values.- 7.2 Substrate Preparation.- 7.3 Film Growth.- 7.3.1 Film Growth Options.- 7.3.2 Dipping LPE Techniques.- 7.3.3 Crucial Factors and Potential Problems.- 7.3.4 Phenomena That Must be Understood and Controlled.- 7.3.5 Process Control.- 7.4 Fabrication of Device Structure.- 7.4.1 Typical Planar Process.- 7.4.2 Variations on the Process.- a) Process Variations in a Planar Structure.- b) Hard Bubble Suppression.- c) Nonplanar Structure.- d) Additive Electroplating.- e) SLM.- f) CD.- 7.4.3 Lithography.- 7.4.4 Potential Problems.- a) Stress.- b) Permalloy Domain Effects.- c) Electromigration.- d) Chemical Interaction.- 7.5 Summary.- 8. Chip Packaging.- 8.1 The Storage Unit.- 8.2 The Storage Module.- 8.3 Limitations on Module Size.- 8.4 Data Integrity.- 8.5 Module Testing.- 8.6 Summary.- 9. Applications.- 9.1 Useful Features of Bubble Devices.- 9.1.1 Intermediate Cost/Speed.- 9.1.2 Major/Minor Loop Organization.- 9.1.3 Lack of Momentum.- 9.1.4 Ladder Organization.- 9.2 General Purpose Storage Units.- 9.3 Storage Hierarchies.- 9.4 Special Purpose Applications.- 9.4.1 Repertory Dialer.- 9.4.2 Speech Announcement.- 9.4.3 Text Editing.- 9.4.4 Flight Recorder.- 9.5 Summary.- 10. Future Prospects.- 10.1 Dependencies of the Module Attributes.- 10.2 Constraints on Active Chip Area.- 10.3 Constraints on Device Cell Density.- a) Resolution of the Device Pattern Exposure System.- b) Resolution of the Device Structure Fabrication Method.- c) Electromigration.- d) Bubble Material Properties.- 10.4 Constraints on Operating Frequency.- 10.5 Loop Length.- 10.6 Areas for Future Research.- 10.7 Summary.- 11. Recent Developments.- 11.1 Contiguous Disk Bubble Devices.- 11.1.1 Charged Wall Bubble Propagation.- 11.1.2 Other Device Elements.- 11.1.3 Complementary Permalloy Devices.- 11.2 Permalloy Bar Storage Chips.- 11.3 Garnet Uniaxial Anisotropy, Ku.- 11.3.1 Ku by Preferential Distribution on Iron Sites.- 11.3.2 High Ku Using Bi Ions.- 11.3.3 Ion-Implantation Modification of Ku.- 11.4 Summary.- References.