Low-dimensional semiconductor quantum structures are a major, high-technological development that has a considerable industrial potential. The field is developing extremely rapidly and the present book represents a timely guide to the latest developments in device technology, fundamental properties, and some remarkable applications. The content is largely tutorial, and the book could be used as a textbook. The book deals with the physics, fabrication, characteristics and performance of devices based on low-dimensional semiconductor structures. It opens with fabrication procedures. The fundamentals of quantum structures and electro-optical devices are dealt with extensively. Nonlinear optical devices are discussed from the point of view of physics and applications of exciton saturation in MQW structures. Waveguide-based devices are also described in terms of linear and nonlinear coupling. The basics of pseudomorphic HEMT technology, device physics and materials layer design are presented. Each aspect is reviewed from the elementary basics up to the latest developments. Audience: Undergraduates in electrical engineering, graduates in physics and engineering schools. Useful for active scientists and engineers wishing to update their knowledge and understanding of recent developments.

This monograph contributes to the mathematical analysis of systems exhibiting hysteresis effects and phase transitions. Its main part begins with a detailed study of models for scalar rate independent hysteresis in the form of hysteresis operators. Applications to ferromagnetism, elastoplasticity and fatigue analysis are presented, and two representative distributed systems with hysteresis operator are discussed. The attention then shifts to the mechanisms of energy dissipation and transformation that induce a hysteretic behavior in continuous media undergoing phase transitions. After an introduction to phenomenological thermodynamic theories of phase transitions, in particular, the Landau-Ginzburg theory and phase field models, several specific models are discussed in detail. These include Falk's model for the hysteresis in shape memory alloys and the phase field models due to Caginalp and Penrose-Fife. The latter are studied both for conserved and non-conserved order parameters. A chapter presenting a mathematical model for the austenite-pearlite and austenite-martensite phase transitions in eutectoid carbon steels concludes the book.

Photonic band gap crystals offer unique ways to tailor light and the propagation of electromagnetic waves. In analogy to electrons in a crystal, EM waves propagating in a structure with a periodically-modulated dielectric constant are organized into photonic bands separated by gaps in which propagating states are forbidden. Proposed applications of such photonic band gap crystals, operating at frequencies from microwave to optical, include zero- threshold lasers, low-loss resonators and cavities, and efficient microwave antennas. Spontaneous emission is suppressed for photons in the photonic band gap, offering novel approaches to manipulating the EM field and creating high-efficiency light-emitting structures. Photonic Band Gap Materials identifies three most promising areas of research. The first is materials fabrication, involving the creation of high quality, low loss, periodic dielectric structures. The smallest photonic crystals yet fabricated have been made by machining Si wafers along (110), and some have lattice constants as small as 500 microns. The second area is in applications. Possible applications presented are microwave mirrors, directional antennas, resonators (especially in the 2 GHz region), filters, waveguides, Y splitters, and resonant microcavities. The third area covers fundamentally new physical phenomena in condensed matter physics and quantum optics. An excellent review of recent development, covering theoretical, experimental and applied aspects. Interesting and stimulating reading for active researchers, as well as a useful reference for non-specialists.

For several years, core level spectroscopies and other, c\osely related, electron spectroscopies have provided very useful information about the atomic composition, the geometric structure, and the electronic structure of condensed matter. Recently, these spectroscopies have also been used for the study of magnetic properties; such studies have a great potential to extend our knowledge and understanding of magnetic systems. This volume collects the lectures presented at the NATO Advanced Study Institute on "Core Level Spectroscopies for Magnetic Phenomena: Theory and Experiment" held at the Ettore Majorana Centre, Erice, Sicily, on 15 to 26 May 1994. The topics considered at the ASI covered a wide range of subjects involving the use of core-level and related spectroscopies to study magnetic phenomena. There are a large and growing number of applications of these spectroscopies to the study of magnetic materials; an important objective of the ASI was to stimulate further growth. The topics covered at the ASI can be placed into three general groups: 1) fundamental principles of core level spectroscopies; 2) basic aspects of magnetic phenomena; and, 3) the combination of the two previous topics embodied in applications of the spectroscopies to magnetism. In all three groups, theoretical interpretations as weH as experimental measurements were presented, often both of these aspects were covered in a single lecture or series oflectures. The theoretical treatments ofthe spectroscopies as weH as of the magnetic phenomena help to establish a framework for understanding many of the experimental measurements on magnetic materials.

The papers published in this volume were presented at the Second International Conference on Ultra-WidebandiShort-Pulse (UWB/SP) Electromagnetics, ApriIS-7, 1994. To place this second international conference in proper perspective with respect to the first conference held during October 8-10, 1992, at Polytechnic University, some background information is necessary. As we had hoped, the first conference struck a responsive cord, both in timeliness and relevance, among the electromagnetic community 1. Participants at the first conference already inquired whether and when a follow-up meeting was under consideration. The first concrete proposal in this direction was made a few months after the first conference by Prof. A. Terzuoli of the Air Force Institute of Technology (AFIT), Dayton, Ohio, who has been a strong advocate of time-domain methods and technologies. He initially proposed a follow-up time-domain workshop under AFIT auspices. Realizing that interest in this subject is lodged also at other Air Force installations, we suggested to enlarge the scope, and received in this endeavor the support of Dr. A. Nachman of AFOSR (Air Force Office of Scientific Research), Bolling Air Force Base, Washington, D.C.

The experimental discovery of the fractional quantum Hall effect (FQHE) at the end of 1981 by Tsui, Stormer and Gossard was absolutely unexpected since, at this time, no theoretical work existed that could predict new struc tures in the magnetotransport coefficients under conditions representing the extreme quantum limit. It is more than thirty years since investigations of bulk semiconductors in very strong magnetic fields were begun. Under these conditions, only the lowest Landau level is occupied and the theory predicted a monotonic variation of the resistivity with increasing magnetic field, depending sensitively on the scattering mechanism. However, the ex perimental data could not be analyzed accurately since magnetic freeze-out effects and the transitions from a degenerate to a nondegenerate system complicated the interpretation of the data. For a two-dimensional electron the positive background charge is well separated from the two gas, where dimensional system, magnetic freeze-out effects are barely visible and an analysis of the data in the extreme quantum limit seems to be easier. First measurements in this magnetic field region on silicon field-effect transistors were not successful because the disorder in these devices was so large that all electrons in the lowest Landau level were localized. Consequently, models of a spin glass and finally of a Wigner solid were developed and much effort was put into developing the technology for improving the quality of semi conductor materials and devices, especially in the field of two-dimensional electron systems."

In this definitive text in the field, the author gives a detailed account of the major problem of applied superconductivitiy-the stability of superconductors. His work focuses on the application of superconductiors to the construction of magnets. Students and engineers will discover the underlying principles of applied superconductivity and will learn how to solve mathematical problems with advanced methods of calculation.

Techniques for the preparation of condensed matter systems have advanced considerably in the last decade, principally due to the developments in microfabrication technologies. The widespread availability of millikelvin temperature facilities also led to the discovery of a large number of new quantum phenomena. Simultaneously, the quantum theory of small condensed matter systems has matured, allowing quantitative predictions. The effects discussed in Quantum Dynamics of Submicron Structures include typical quantum interference phenomena, such as the Aharonov-Bohm-like oscillations of the magnetoresistance of thin metallic cylinders and rings, transport through chaotic billiards, and such quantization effects as the integer and fractional quantum Hall effect and the quantization of the conductance of point contacts in integer multiples of the conductance quantum'. Transport properties and tunnelling processes in various types of normal metal and superconductor tunnelling systems are treated. The statistical properties of the quantum states of electrons in spatially inhomogeneous systems, such as a random, inhomogeneous magnetic field, are investigated. Interacting systems, like the Luttinger liquid or electrons in a quantum dot, are also considered. Reviews are given of quantum blockade mechanisms for electrons that tunnel through small junctions, like the Coulomb blockade and spin blockade, the influence of dissipative coupling of charge carriers to an environment, and Andreev scattering. Coulomb interactions and quantization effects in transport through quantum dots and in double-well potentials, as well as quantum effects in the motion of vortices, as in the Aharonov-Casher effect, arediscussed. The status of the theory of the metal-insulator and superconductor-insulator phase transitions in ordered and disordered granular systems are reviewed as examples in which such quantum effects are of great importance.

This monograph presents electric therapy for the reduction of pain in a different way than the classical well known manner to use electric currents of various kinds for this purpose. It started when Melzack and Wall published their theory of pain. But contrary to most researchers, the author looked for a proof which objectively could demonstrate, that electric current would have an influence on nerve fibers conducting pain. Starting from this model of demonstration, an optimal type of current could be selected as well as optimal electrode positions and sizes of electrodes. It is an absolute new approach presenting the results of applying the type of current to more than 17.000 patients suffering from any kind of pain. Anatomic sketches and photo-documentation of electrode positions for many conditions allow the reader to obtain identical degree of pain reduction as the author describes from his great experience. In addition, a brief theoretical introduction and discussion of the influence of weather on pain is given. Practical forms for the management of pain are presented in an appendix. 256 references and a table of suitable apparatus with their essential technical characteristics facilitates correct application of this new principle.

The Seventh International Symposium on Gaseous Dielectrics was held in Knoxville, Tennessee, U. S. A. , on April 24-28, 1994. The symposium continued the interdisciplinary character and comprehensive approach of the preceding six symposia. Gaseous DielecIries VII is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied and industrial areas of gaseous dielectrics. It is hoped that Gaseous DielecIries VII will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Seventh International Symposium on Gaseous Dielectrics consisted of G. Addis (U. S. A. ), L. G. Christophorou (U. S. A. ), F. Y. Chu (Canada), A. H. Cookson (U. S. A. ), O. Farish (U. K. ), I. Gallimberti (Italy) , A. Garscadden (U. S. A. ), D. R. James (U. S. A. ), E. Marode (France), T. Nitta (Japan), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (U. S. A. ), R. J. Van Brunt (U. S. A. ), and W. Zaengl (Switzerland). The local arrangements committee consisted of members of the Health Sciences Research Division and personnel of the Conference Office of the Oak Ridge National Laboratory, and staff of the University of Tennessee (UTK). The contributions of each member of these committees, the work of the Session Chairmen, the interest of the participants, and the advice of innumerable colleagues are gratefully acknowledged. I am especially indebted to Dr. Isidor Sauers, Dr. David R. James, Mrs.

Hysteresis effects occur in science and engineering: plasticity, ferromagnetism, ferroelectricity are well-known examples. Modelling and mathematical analysis of hysteresis phenomena have been addressed by mathematicians only recently, but are now in full development.
This volume provides a self-contained and comprehensive introduction to the analysis of hysteresis models, and illustrates several new results in this field. First the classical models of Prandtl, Ishlinskii, Preisach and Duhem are formulated and studied, using the concept of "hysteresis operator." A new model of discontinuous hysteresis is introduced. Several partial differential equations containing hysteresis operators are studied in the framework of Sobolev spaces.

Based on courses given at the Ecole Polytechnique in France, this book covers not only the fundamental physics of semiconductors, but also discusses the operation of electronic and optical devices based on semiconductors. It is aimed at students with a good background in mathematics and physics, and is equally suited for graduate-level courses in condensed-matter physics as for self-study by engineers interested in a basic understanding of semiconductor devices.

Spin glasses are disordered magnetic systems that have led to the development of mathematical tools with an array of real-world applications, from airline scheduling to neural networks. "Spin Glasses and Complexity" offers the most concise, engaging, and accessible introduction to the subject, fully explaining what spin glasses are, why they are important, and how they are opening up new ways of thinking about complexity.

This one-of-a-kind guide to spin glasses begins by explaining the fundamentals of order and symmetry in condensed matter physics and how spin glasses fit into--and modify--this framework. It then explores how spin-glass concepts and ideas have found applications in areas as diverse as computational complexity, biological and artificial neural networks, protein folding, immune response maturation, combinatorial optimization, and social network modeling.

Providing an essential overview of the history, science, and growing significance of this exciting field, S"pin Glasses and Complexity" also features a forward-looking discussion of what spin glasses may teach us in the future about complex systems. This is a must-have book for students and practitioners in the natural and social sciences, with new material even for the experts.

"Great progress has been made in electrical science, chiefly in Germany, by cultivators of the theory of action at a distance. The valuable electrical measurements of W. Weber are interpreted by him according to this theory, and the electromagnetic speculation which was originated by Gauss, and carried on by Weber, Riemann, F. and C. Neumann, Lorenz, etc. , is founded on the theory of action at a distance, but depending either directly on the relative velocity of the particles, or on the gradual propagation of something, whether potential or force, from the one particle to the other. The great success which these eminent men have attained in the application of mathematics to electrical phenomena, gives, as is natural, additional weight to their theoretical speculations, so that those who, as students of electricity, turn to them as the greatest authorities in mathematical electricity, would probably imbibe, along with their mathematical methods, their physical hypothesis. These physical hypotheses, however, are entirely alien from the way of looking at things which I adopt, and one object which I have in view is that some of those who wish to study electricity may, by reading this treatise, come to see that there is another way of treating the subject, which is no less fitted to explain the phenomena, and which, though in some parts it may appear less definite, corresponds, as I think, more faithfuHy with our actual knowledge, both in what it affirms and in what it leaves undecided.

The NATO Advanced Research Workshop on Coherent Optical Processes in Semiconductors was held in Cambridge, England on August 11-14,1993. The idea of holding this Workshop grew from the recent upsurge in activity on coherent transient effects in semiconductors. The development of this field reflects advances in both light sources and the quality of semiconductor structures, such that tunable optical pulses are now routinely available whose duration is shorter than the dephasing time for excitonic states in quantum wells. It was therefore no surprise to the organisers that as the programme developed, there emerged a heavy emphasis on time-resolved four-wave mixing, particularly in quantum wells. Nevertheless, other issues concerned with coherent effects ensured that several papers on related problems contributed some variety. The topics discussed at the workshop centred on what is a rather new field of study, and benefited enormously by having participants representing many of the principal groups working in this area. Several themes emerged through the invited contributions at the Workshop. One important development has been the careful examination of the two-level model of excitonic effects; a model which has been remarkably successful despite the expected complexities arising from the semiconductor band structure. Indeed, modest extensions to the two level model have been able to offer a useful account for some of the complicated polarisation dependence of four-wave mixing signals from GaAs quantum wells. This work clearly is leading to an improved understanding of excitons in confined systems.

Cosmic electrodynamics is the specific branch of plasma physics which studies electromagnetic phenomena -- mostly the role of electromagnetic forces in dynamics of highly-conducting compressible medium in the solar interior and atmosphere, solar wind, in the Earth's magnetosphere and magnetospheres of other planets as well as pulsars and other astrophysical objects. This textbook is written to be used at several different levels. It is aimed primarily at beginning graduate students who are assumed to have a knowledge of basic physics. Starting from the language of plasma physics, from Maxwell's equations, the author guides the reader into the more specialized concepts of cosmic electrodynamics. The main attention in the book is paid to physics rather than maths. However, the clear mathematical image of physical processes in space plasma is presented and spelled out in the surrounding text. There is not another way to work in modern astrophysics at the quantitative level. The book will also be useful for professional astronomers and for specialists, who investigate cosmic plasmas from space, as well as for everybody who is interested in modern astrophysics.

Intersubband transitions in quantum wells have attracted tremendous attention in recent years, mainly due to the promise of applications in the mid and far-infrared regions (2--20 mum). Many of the papers presented in Quantum Well Intersubband Transition Physics and Devices are on the basic linear intersubband transition processes, detector physics and detector application, reflecting the current state of understanding and detector applications, where highly uniform, large focal plane arrays have been demonstrated. Other areas are still in their early stages, including infrared modulation, harmonic generation and emission.

Magnetostatic Waves and their Applications is the first book devoted to magnetostatic waves. The book gives a thorough review of the field suitable for scientists, engineers and advanced students involved in magnetism and microwave electronics new to this area. It covers the field from essential physics to applications in microwave electronics, with details of the materials and materials processing methods included.

During the past 30 years materials science has developed into a full-fledged field for basic and applied scientific enquiry. Indeed, materials scientists have devoted their efforts to creating new materials with improved electronic, magnetic, thermal, mechanical, and optical properties. Often unnoticed, these new materials are rapidly invading our homes and automobiles, and may be found in our utensils, electronic equipment, textiles, home appliances, and electric motors. Even though they may go unnoticed, these new materials have either improved the efficiency and lifetime of these items or have reduced their weight or cost. In particular, magnetically ordered materials are useful in various applications, such as motors, magnetic imaging, magnetic recording, and magnetic levitation. Hence, much effort has been devoted to the development of better hard magnetic materials, magnetic thin films, and molecular magnets. During the same period of time, Mossbauer-effect spectroscopy has grown from a laboratory curiosity to a mature spectroscopic technique, a technique that probes solid-state materials at specific atomic sites and yields microscopic information on the magnetic and electronic properties of these materials. Iron-57 is the most commonly and easily used Mossbauer-effect isotope and, of course, is particularly relevant for the study of magnetic materials. Various applications of Mossbauer spectroscopy to magnetic materials are discussed in the first six chapters of this volume. Other isotopes such as zinc-67 and gadolinium-ISS have recently been used to study the electronic properties of zinc compounds and the electronic and magnetic properties of rare-earth transition metal compounds.

This book is based on the contributions to a course, entitled Applied Magnetism, which was the 25th Course of the International School of Materials Science and Technology. The Course was held as a NATO Advanced Study Institute at the Ettore Majorana Centre in Erice, Sicily, Italy between the 1st and 12th July 1992, and attracted almost 70 participants from 15 different countries. The book deals with the theory, experiments and applications of the main topical areas of applied magnetism. These selected areas include the physics of magnetic recording, magnetic and magneto-optic recording devices, systems and media, magnetic fine particles, magnetic separation, domains and domain walls in soft magnetic materials, permanent magnets, magnetoresistance, thin film magneto-optics, and finally, microwave, optical and computational magnetics. The material is organised into I 0 self-contained chapters which together provide a comprehensive coverage of the subject of applied magnetism. The aim is to emphasise the connection between the fundamental theoretical concepts, key experiments and the important technological developments which have been achieved in this field up to the present time. Moreover, when and where possible, pointers to future trends are indicated which hopefully, together with the background material, will promote further advancement of research. The organizing committee would like to acknowledge the sponsorship of the NATO Scientific Affairs Division, the National Science Foundation of the USA, the Science and Engineering Research Council of the UK, the Italian Ministry of Education, the Italian Ministry of University and Scientific Research and the Sicilian Regional Government.

This volume contains the papers presented at the NATO Advanced Research Workshop on "Magnetism and Structure in Systems of Reduced Dimension," held at l'Institut d'Etudes Scientifiques de Cargese - U.M.S. - C.N.R.S. - Universite de Corte Universite de Nice Sophia - Antipolis during June 15-19, 1992. The ordering of papers in the volume reflects the sequence of papers presented at the workshop. The aim was not to segregate the papers into rigidly defmed areas but to group the papers into small clusters, each cluster having a common theme. In this way the parallel, rather than serial, development of areas such as preparation of films, magnetic and structural characterization was highlighted. Indeed the success of the field depends on such parallel development and is assisted by workshops of this nature and the international collaborations which they foster. The organizers and participants of the NATO workshop express their thanks to Mme. Marie-France Hanseier and the staff at l'Institut d'Etudes Scientifiques de Cargese U.M.S. - C.N.R.S. - Universite de Corte - Universite de Nice Sophia - Antipolis for making the workshop and local arrangements a memorable success. Warm thanks are also expressed to Varadachari Sadagopan and Pascal Stefanou for their encouragement and help in making the workshop a reality. We are also grateful to Kristl Hathaway, Larry Cooper and Gary Prinz for advice in developing the workshop program."

In the years since the book of Lozanskii and Firsov "The Theory of Spark" 1975] was published, a number of experimental and theoretical studies in the physics of electric breakdown in gases were conducted. As a result of these studies, the concept of a wavelike nature of breakdown initiated by single high-voltage electric pulses or by a constant electric field was confirmed. Theoretical models in which the concept of breakdown in a constant external field was developed were first exposed in the above-named book in the chapter "Development of a streamer regarded as an ionization wave," written by Rodin and Starostin. This book treats the initial stage of electric breakdown as a wave pro cess. The wavelike nature of the phenomena under consideration is pre sented for streamers and sliding discharges, for electric breakdown develop ment in long discharge tubes as well as in gas-filled gaps. Chapter 1 gives a qualitative consideration of phenomena determin ing the electric breakdown of gases. The experimental data and theoretical results are exposed and discussed with application to streamers, plane ion ization waves, breakdown waves in long tubes, and propagation of sliding discharges. The subject of this chapter may be considered as an area of applications of different theoretical models, formulas, and estimates that are presented in other chapters of the book."

In this book, the author draws on his broad experience to describe both the theory and the applications of wave propagations. The contents are presented in four parts and the sequence of these parts reflect the development of ionospheric and propagational research in areas such as space research geophysics and communications. The first part of the book presents an outline of the theory of electromagnetic waves propagating in a cold electron plasma. For reference, vector analysis, dyadics and eigenvalues introduced in this part are presented in the appendices. Practical aspects of radio wave propagation are the subject of the second part. The typical conditions in different frequency ranges are discussed and the irregular features of the ionospheric structure such as sound and gravity waves are also considered. Warm plasma and the effects of ions are considered in the third part, which includes a discussion of sound-like waves in electron and ion plasmas. Nonlinear effects and instabilities are described in the fourth part.

The NATO Advanced Research Workshop on "Nanomagnetic Devices" was held in Miraflores de la Sierra, Madrid, Spain, from 14 to 19 September 1992. This book contains 21 invited articles related to suggestive and relevant aspects of Magnetism. The NATO Advanced Research Workshop was Co-directed by R.C. O'Handley, B. Heinrich and A. Hernando. The organisers as well as the participants are gratefully acknowledged to the NATO Science Committee. I also wish to thank the publishers for their advice and help in organizing the book. xi DESIDERATA OF STORAGE DEVICES C.E. YEACK-SCRANTON IBM Corporation, E02/005 5600 Cottle Road San Jose, CA 95139 USA ABSTRACT. Typical requirements on cost, capacity, and performance of today's magnetic storage devices and industry trends in these attributes are given. Scaling components, devices, and materials is shown to be a key factor in further improvement, Challenges to continued scaling are reviewed, particularly as they relate to magnetic nano-structures, materials, and characterization techniques.

The workshop on "Optical Properties of Low Dimensional Silicon sL Structures" was held in Meylan, France on March, I yd, 1993. The workshop took place inside the facilities of France Telecom- CNET. Around 45 leading scientists working on this rapidly moving field were in attendance. Principal support was provided by the Advanced Research Workshop Program of the North Atlantic Treaty Organisation (NATO). French Delegation a l'Armement and CNET gave also a small financial grant, the organisational part being undertaken by the SEE and CNET. There is currently intense research activity worldwide devoted to the optical properties of low dimensional silicon structures. This follow the recent discovery of efficient visible photoluminescence (PL) from highly porous silicon. This workshop was intended to bring together all the leading European scientists and laboratories in order to reveal the state of the art and to open new research fields on this subject. A large number of invited talks took place (12) together with regular contribution (20). The speakers were asked to leave nearly 1/3 of the time to the discussion with the audience, and that promoted both formal and informal discussions between the participants.