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.

This book is t~e fifth in aseries of scientific textbooks designed to cover advances in selected research fields from a basic and general view point. The reader is taken carefully but rapidly through the introductory material in order that t~e significance of recent developments can be understood with only limited initial knowledge. The inclusion in the Appendix of the abstracts of many of the more important papers in the field provides further assistance for the non-specialist, and acts as aspringboard to supplementary reading for those who wish to consult the original liter ature. Surface analysis has been the subject of numerous books and review articles, and the fundamental scientific principles of t~e more popular techniques are now reasonably weIl established. This book is concerned with the very powerful techniques of Auger electron and X-ray photoelectron spectroscopy (AES and XPS), with an emphasis on how they may be performed as part of a modern analytical facility. Since the development of AES and XPS in the late 1960s and early 1970s there have been great strides forward in the sensitivities and resolutions of the instrumentation. Simultaneously, these spectroscopies have undergone a veritable explosion, both in their acceptance alongside more routine ana1ytical techniques and in the range of problems and materials to which they are applied. As a result, many researchers in industry and in academia now come into contact with AES and XPS not as specialists, but as users.

The research of unitary concepts in solid state and molecular chemistry is of current interest for both chemist and physicist communities. It is clear that due to their relative simplicity, low dimensional materials have attracted most of the attention. Thus, many non-trivial problems were solved in chain systems, giving some insight into the behavior of real systems which would otherwise be untractable. The NATO Advanced Research Workshop on "Organic and Inorganic Low-Dimensional Crystalline Materials" was organized to review the most striking electronic properties exhibited by organic and inorganic sytems whose space dimensionality ranges from zero (Od) to one (1d), and to discuss related scientific and technological potentials. The initial objectives of this Workshop were, respectively: i) To research unitary concepts in solid state physics, in particular for one dimensional compounds, ii) To reinforce, through a close coupling between theory and experiment, the interplay between organic and inorganic chemistry, on the one hand, and solid state physics on the other, iii) To get a salient understanding of new low-dimensional materials showing "exotic" physical properties, in conjunction with structural features.

This volume contains the papers presented at the NATO Advanced Research Workshop on Localization and Propagation o[ Classical Waves in Random and Periodic Media held in Aghia Pelaghia, Heraklion, Crete, May 26- 30, 1992. The workshop's goal was to bring together theorists and experimentalists from two related areas, localization and photonic band gaps, to highlight their common interests. The objectives of the workshop were (i) to assess the state of-the-art in experimental and theoretical studies of structures exhibiting classical wave band gaps and/or localization, (ii) to discuss how such structures can be fabricated to improve technologies in different areas of physics and engineering, and (iii) to identify problems and set goals for further research. Studies of the propagation of electromagnetic (EM) waves in periodic and/or disordered dielectric structures (photonic band gap structures) have been and continue to be a dynamic area of research. Anderson localization of EM waves in disordered dielectric structures is of fundamental interest where the strong ei-ei interaction efFects entering the eIectron-localization are absent.

Semimagnetic semiconductors (SMSC) and diluted magnetic semiconductors (DMS) have in the past decade attracted considerable attention because they confer many new physical properties on both bulk materials and heterostructures. These new effects are due either to exchange interactions between magnetic moments on magnetic ions, or to exchange interactions between magnetic moments and the spin of the charge carrier. These effects vary with the transition metal (Mn, Fe, Co) or rare earth (Eu, Gd, etc) used and thus provide a range of different situations. The field is very large (zero gap, small gap, wide gap), and the magnetic properties also are very rich (paramagnetic spin glass, antiferromagnetism). These materials are very convenient for studying the magnetism (the magnetism is diluted) or the superlattices (SL) with a continuous change from type II SL to type III SL. This Course attempted to provide a complete overview of the topic. The participants of this summer school held in Erice came from ten countries and were from various backgrounds and included theoreticians, experimentalists, physicists, and chemists. Consequently, an attempt was made to make the Course as thorough as possible, but at the same time attention was devoted to basic principles. The lecturers, drawn from all the groups in the world involved in the field, were asked to be very didactic in their presentation. After two introductory lectures, Dr.

The Conference on the Science and Technology of Thin Film Superconductors was conceived in the early part of 1988 as a forum for the specialist in thin film superconductivity. The conference was held on November 14-18, 1988, in Co lorado Springs, Co lorado. Al though many excellent superconductivity conferences had been convened in the wake of the 1986-1987 discoveries in high temperature superconductivity, thin film topics were often dispersed among the sessions of a more general conference agenda. The response to the Conference on the Science and Technology of Thin Film Superconductors confirmed the need for an extended conference devoted to thin film superconductors. These proceedings are a major contribution to the technnology of thin film superconductivity because of the breadth and quality of the articles provided by leaders in the field. The proceedings are divided into articles on laser deposition, sputtering, evaporation, metal organic chemical vapor deposition, thick film, substrate studies, characterization, patterning and applications, and general properties. Most of the articles discuss scientific issues for high temperature thin film superconductors, although the conference was to be a forum for technology and scientific questions for both low and high temperature superconductivity. For the first day of the 5 day conference, Lawrence Berkeley Laboratory had organized an excellent set of short courses in superconduc t ing thin film devices.

The XIV International Workshop on Condensed Matter Theories has been held at the Elba International Physics Center (EIPC), Marciana Marina, Isola d'Elba, Italy, from 18-23 June, 1990. The Workshop started in 1977 in Sao Paolo, Brazil, as the 1st Pan American Workshop on Condensed Matter Theories, with the purpose of bringing together scientists from the Western countries, working in many different topics of Condensed Matter Theories, to facilitate exchanges of ideas and technologies from different areas as well as collaborations among the scientists. The next five Workshops were held at Trieste, Italy (1978), in Buenos Aires, Argentina ( 1979), in Caracas, Venezuela (1980), in Mexico City, Mexico (1981) and in St. Louis, Missouri, U. S. A. (1982). Given the international dimension reached by the Workshop, it was decided to extend it into an International Workshop, which was held for the first time in Altenberg, Germany (1983). The next editions took place in Granada, Spain (1984), San Francisco, California, U. S. A. (1985), Argonne, Illinois, U. S. A. (1986), Oulu, Finland (1987), Taxco, Mexico (1988) and Campos do Jordao, Brasil (1989). Many scientists have contributed to the development of the various editions of the Work shop. However, a particular mention has to be made to Profs. Manuel de Llano and Angel Plastino who initially proposed the Workshop and carried it forward, and to Prof. J . W. Clark, whose efforts have been of immense help to its recent developments.

The operation of semiconductor devices depends upon the use of electrical potential barriers (such as gate depletion) in controlling the carrier densities (electrons and holes) and their transport. Although a successful device design is quite complicated and involves many aspects, the device engineering is mostly to devise a "best" device design by defIning optimal device structures and manipulating impurity profIles to obtain optimal control of the carrier flow through the device. This becomes increasingly diffIcult as the device scale becomes smaller and smaller. Since the introduction of integrated circuits, the number of individual transistors on a single chip has doubled approximately every three years. As the number of devices has grown, the critical dimension of the smallest feature, such as a gate length (which is related to the transport length defIning the channel), has consequently declined. The reduction of this design rule proceeds approximately by a factor of 1. 4 each generation, which means we will be using 0. 1-0. 15 ). lm rules for the 4 Gb chips a decade from now. If we continue this extrapolation, current technology will require 30 nm design rules, and a cell 3 2 size < 10 nm , for a 1Tb memory chip by the year 2020. New problems keep hindering the high-performance requirement. Well-known, but older, problems include hot carrier effects, short-channel effects, etc. A potential problem, which illustrates the need for quantum transport, is caused by impurity fluctuations.

Soon after the discovery of quantum mechanics, group theoretical methods were used extensively in order to exploit rotational symmetry and classify atomic spectra. And until recently it was thought that symmetries in quantum mechanics should be groups. But it is not so. There are more general algebras, equipped with suitable structure, which admit a perfectly conventional interpretation as a symmetry of a quantum mechanical system. In any case, a "trivial representation" of the algebra is defined, and a tensor product of representations. But in contrast with groups, this tensor product needs to be neither commutative nor associative. Quantum groups are special cases, in which associativity is preserved. The exploitation of such "Quantum Symmetries" was a central theme at the Ad vanced Study Institute. Introductory lectures were presented to familiarize the participants with the al gebras which can appear as symmetries and with their properties. Some models of local field theories were discussed in detail which have some such symmetries, in par ticular conformal field theories and their perturbations. Lattice models provide many examples of quantum theories with quantum symmetries. They were also covered at the school. Finally, the symmetries which are the cause of the solubility of inte grable models are also quantum symmetries of this kind. Some such models and their nonlocal conserved currents were discussed.

Distinct scientific communities are usually involved in the three fields of quasi-crystals, of liquid crystals, and of systems having modulated crystalline structures. However, in recent years, there has been a growing feeling that a number of common problems were encountered in the three fields. These comprise the need to recur to "exotic" spaces for describing the type of order of the atomic or molecular configurations of these systems (Euclidian "superspaces" of dimensions greater than 3, or 4-dimensional curved spaces); the recognition that one has to deal with geometrically frustrated systems, and also the occurence of specific excitations (static or dynamic) resulting from the continuous degeneracies of the stable structures considered. In the view of discussing these problems, aNA TO-Advance Research Workshop has assembled in Preveza (Greece), in september 1989,50 experts of the three considered fields (with an equal proportion of theorists and experimentalists). 35 hours of conferences and discussions have led to a more detailed evaluation of the similarities and of the differences in the approaches implemented in the studies of the three types of systems. The papers contained in this NATO-series book provide the substance of this workshop. The reader will find three types of papers. Some very short papers giving the main ideas stated on a subject. Papers comprising 8-10 pages which stick closely to the contents of the talks presented. Longer papers providing more extensively the background and results relative to a given topic. It is worth summarizing the principal outputs of the workshop.

The past three decades have been a period where useful current and voltage instabilities in solids have progressed from exciting research problems to a wide variety of commercially available devices. Materials and electronics research has led to devices such as the tunnel (Esaki) diode, transferred electron (Gunn) diode, avalanche diodes, real-space transfer devices, and the like. These structures have proven to be very important in the generation, amplification, switching, and processing of microwave signals up to frequencies exceeding 100 GHz. In this treatise we focus on a detailed theoretical understanding of devices of the kind that can be made unstable against circuit oscillations, large amplitude switching events, and in some cases, internal rearrangement of the electric field or current density distribution. The book is aimed at the semiconductor device physicist, engineer, and graduate student. A knowledge of solid state physics on an elementary or introductory level is assumed. Furthermore, we have geared the book to device engineers and physicists desirous of obtaining an understanding substantially deeper than that associated with a small signal equivalent circuit approach. We focus on both analytical and numerical treatment of specific device problems, concerning ourselves with the mechanism that determines the constitutive relation governing the device, the boundary conditions (contact effects), and the effect of the local circuit environment.

The interest in the problem of surface diffusion has been steadily growing over the last fifteen years. This is clearly evident from the increase in the number of papers dealing with the problem, the development of new experimental techniques, and the specialized sessions focusing on diffusion in national and international meetings. Part of the driving force behind this increasing activity is our recently acquired ability to observe and possibly control atomic scale phenomena. It is now possible to look selectively at individual atomistic processes and to determine their relative importance during growth and reactions at surfaces. The number of researchers interested in this problem also has been growing steadily which generates the need for a good reference source to farniliarize newcomers to the problem. While the recent emphasis is on the role of diffusion during growth, there is also continuing progress on the more traditional aspects of the problem describing mass transport in an ensemble of particles. Such a description is based on the statistical mechanical analysis of a collection of particles that mutually interact and develop correlations. An average over the multitude of atomistic processes that operate under these conditions is necessary to fully describe the dynamics in the system.

Since the early days of modem physics spectroscopic techniques have been employed as a powerful tool to assess existing theoretical models and to uncover novel phenomena that promote the development of new concepts. Conventionally, the system to be probed is prepared in a well-defined state. Upon a controlled perturbation one measures then the spectrum of a single particle (electron, photon, etc.) emitted from the probe. The analysis of this single particle spectrum yields a wealth of important information on the properties of the system, such as optical and magnetic behaviour. Therefore, such analysis is nowadays a standard tool to investigate and characterize a variety of materials. However, it was clear at a very early stage that real physical compounds consist of many coupled particles that may be excited simultaneously in response to an external perturbation. Yet, the simultaneous (coincident) detection of two or more excited species proved to be a serious technical obstacle, in particular for extended electronic systems such as surfaces. In recent years, however, coincidence techniques have progressed so far as to image the multi-particle excitation spectrum in an impressive detail. Correspondingly, many-body theoretical concepts have been put forward to interpret the experimental findings and to direct future experimental research. This book gives a snapshot of the present status of multi-particle coincidence studies both from a theoretical and an experimental point of view. It also includes selected topical review articles that highlight the achievements and the power of coincident techniques.

This volume represents the primary lectures of the NATO Advanced Study Institute (ASI) on "Nuclear Magnetic Resonance in Modern Technology," which was held at Sarigerme Park (near the Dalaman Airport) on the southern Aegean shore of Turkey from August 23 to September 4, 1992. As indicated in the title, this ASI was aimed at examining, displaying, and perhaps influencing, the role of nuclear magnetic resonance (NMR) in modern technological activity. The lectures summarized in this volume and the numerous short contributed talks and posters were primarily aimed at the question, "What is NMR doing in support of modern technology?" During the main discussion periods and the numerous small scheduled meetings of specific interest groups this same topic was also addressed, along with questions like, "What could or should NMR be doing in support of modern technology?" With this kind of subject orientation, the organizers attempted to include a large participation at the ASI from scientists and engineers from diverse private industries in which NMR does, or perhaps should, play a substantial role in supporting or optimizing technology. Perhaps because of a combination of worldwide industrial contractions and residual corporate nervousness regarding the then recent Gulf War (which caused a one-year postponement of this ASI), the participation from private industry was numerically disappointing. We hope that this book will serve to bring the role of NMR in modern industry to the attention of numerous industrial scientists and engineers who were unable to attend the AS .

The present volume contains the text of the invited talks delivered at the Eighth International Conference on Recent Progress in Many-Body Theories held at SchloB Seggau, Province of Styria, Austria, during the period August 22-26, 1994. The pro ceedings of the Fifth Conference (Oulu, Finland 1987), the Sixth Conference (Arad, Israel 1989) and the Seventh Conference (Minneapolis, USA 1991) have been published. by Plenum as the first three volumes of this series. Papers from the First Conference (Trieste, Italy 1978) comprise Nuclear Physics volume A328, Nos. 1 and 2, the Second Conference (Oaxtepec, Mexico 1979) was published by Springer-Verlag as volume 142 of "Lecture Notes in Physics," entitled "Recent Progress in Many Body Theories." Vol ume 198 of the same series contains the papers from the Third Conference (Altenberg, 1983). These volumes intend to cover a broad spectrum of current research topics in physics that benefit from the application of many-body theories for their elucidation. At the same time there is a focus on the development and refinement of many-body methods. One of the major aims of the conference series has been to foster the exchange of ideas among physicists working in such diverse areas as nuclear physics, quantum chemistry, complex systems, lattice Hamiltonians, quantum fluids and condensed matter physics. The present volume contains contributions from all these areas. th The conference was dedicated on the occasion of Ludwig Boltzmann's 150 birthday."

Semiconducting and Insulating Crystals details how absorption spectroscopy provides information on the nature, concentration, charge state and configuration of impurities in crystals and also on their kinetics and transformations under annealing. After an introduction of the bulk optical properties of semiconductors and insulators and of impurities in crystals, this book presents the physical bases necessary for the understanding of impurity spectra. The description of various set-ups and accessories used in absorption spectroscopy is followed by a presentation of experimental results on specific impurities and classes of impurities and their relation with those obtained by various computation and by other experimental techniques.

Nanometer CMOS RFICs for Mobile TV Applications focuses on how to break the trade-off between power consumption and performance (linearity and noise figure) by optimizing the mobile TV front-end dynamic range in three hierarchical levels: the intrinsic MOSFET level, the circuit level, and the architectural level. It begins by discussing the fundamental concepts of MOSFET dynamic range, including nonlinearity and noise. It then moves to the circuit level introducing the challenges associated with designing wide-dynamic range, variable-gain, broadband low-noise amplifiers (LNAs). The book gives a detailed analysis of a new noise-canceling technique that helps CMOS LNAs achieve a sub - 2 dB wideband noise figure. Lastly, the book deals with the front-end dynamic range optimization process from the systems perspective by introducing the active and passive automatic gain control (AGC) mechanism.

The individual papers that comprise this monograph are derived from two American Chemical Society (ACS) Fall National Meetings that focused on the current uses of synchrotron radiation (SR) research techniques. The first Symposium was held in Washington, DC, in August 1994, and the second convened in Chicago, IL, in August 1995. The intent of these symposia was to present a broad overview of several current topics in industrial, chemical, and materials-based SR research to a chemically inclined audience. The SR techniques covered were divided roughly into the three general fields of industrial, chemical, and materials science for this purpose. Included within these four categories are environmental, geologic, atomic/molecular, analytical, solid state physics, surface science, and biological applications of SR. There is little doubt that structural biology and environmental science are the largest growth areas in SR research as this monograph goes to press. The spirit of these symposia was to bring together the expert synchrotron radiation user with new and potential users of SR techniques. There are now a preponderance of particle storage rings, located throughout the world, devoted exclusively to the production of SR. There have been great improvements in the particle accelerators and storage rings from which SR emanates. These newest third generation SR sources are the result of the successful collaboration between SR users and accelerator physicists which has made a reality out of experiments never before possible.

Just over 25 years ago the first laser-excited Raman spectrum of any crystal was obtained. In November 1964, Hobden and Russell reported the Raman spectrum of GaP and later, in June 1965, Russell published the Si spectrum. Then, in July 1965, the forerunner of a series of meetings on light scattering in solids was held in Paris. Laser Raman spectroscopy of semiconductors was at the forefront in new developments at this meeting. Similar meetings were held in 1968 (New York), 1971 (Paris) and 1975 (Campinas). Since then, and apart from the multidisciplinary biennial International Conference on Raman Spectroscopy there has been no special forum for experts in light scattering spectroscopy of semiconductors to meet and discuss latest developments. Meanwhile, technological advances in semiconductor growth have given rise to a veritable renaissance in the field of semiconductor physics. Light scattering spectroscopy has played a crucial role in the advancement of this field, providing valuable information about the electronic, vibrational and structural properties both of the host materials, and of heterogeneous composite structures. On entering a new decade, one in which technological advances in lithography promise to open even broader horirons for semiconductor physics, it seemed to us to be an ideal time to reflect on the achievements of the past decade, to be brought up to date on the current state-of-the-art, and to catch some glimpses of where the field might be headed in the 1990s.

Proceedings of a NATO ASI/18th Course of the International School of Crystallography, held in Erice, Sicily, Italy, April 18--29, 199

Rapid thermal processing has contributed to the development of single wafer cluster processing tools and other innovations in integrated circuit manufacturing environments. Borisenko and Hesketh review theoretical and experimental progress in the field, discussing a wide range of materials, processes, and conditions. They thoroughly cover the work of international investigators in the field.

The workshop entitled Magnetic Susceptibility of Superconductors and other Spin Systems (S4) was held at Coolfont Resort and Health Spa. located near Berkley Springs West Virginia on May 20-23. 1991. There were over sixty attendees. approximately half from the United States. the remainder representing over twelve different countries. The international character of the workshop may be gleaned form the attendee list, included in this volume. The intent of the workshop was to bring together those experimentalists and theoreticians whose efforts have resulted in significant recent contributions to the development and use of the ac susceptibility technique as well as to the interpretation of data obtained from these measurements. Many spirited discussions occurred during and after the presentations. These are reflected in the manuscripts contained in these proceedings. Although camera ready manuscripts were required from all participants at registration, all manuscripts were revised and reflect the lively exchanges that followed each presentation. The small size of the workshop allowed the participants a high degree of flexibility. Consequently when a controversial topic such as "the irreversibility line" emerged, a special session was organized on the spot. At the suggestion of Ron Goldfarb, participants were invited to contribute a one page summary containing their thoughts on the topic. These stand alone contributions were retyped and included as submitted, with only minor editorial changes. These proceedings are intended for those experienced scientists new to the field and graduate students just beginning their research.

This conference is the second on the Science and Technology of Thin Film Superconductors. It proved to be an excellent forum for these specialists in thin film superconductivity. The conference, held April 30-May 4, 1990, in Denver, Colorado, hosted 170 researchers from 17 countries. The response to the conference again emphasized the need for a meeting devoted to the science and technology of thin film superconductors. The breadth of artic1es and advances made in this technology since the first conference in November 1988, reflect on the maturity of the topic. These proceedings contain artic1es on deposition methods by sputtering, e1ectron beam evaporation, resistive evaporation, laser ablation, chemical vapor deposition and electrodeposition, and on other studies related to substrates, thermodynamics of formation, grain boundaries and weak links, characterization, and some practical applications. The program committee was pleased with the quality of the publications and contributed articles. This conference was highlighted by a fuU day dedicated to presentations from the federallaboratories, discussing a wide range of topics on the fabrication, characterization, and theory of high-temperature superconductor thin films. Other highlights at the conference dealt with (1) critical parameters or problems in measuring critical current density and other important parameters, and (2) problems of scale-up, reproducibility, and amenability to device fabrication. It became evident from the presentations that three issues were developing into critical issues for the ultimate practical application of high temperature superconductor thin films."