Traditionally, magnetic materials have been metals or, if inorganic compounds such as oxides, of continuous lattice type. However, in recent years chemists have synthesized increasing numbers of crystalline solids based on molecular building blocks in the form of coordination and organometallic complexes or purely organic molecules, which exhibit spontaneous magnetization. In striking contrast to conventional magnets, these materials are made from solutions close to room temperature rather than by metallurgical or ceramic methods. This book, which originates from contributions to a Discussion Meeting of The Royal Society of London, brings together many of the leading international practitioners in the field, who survey their own recent work and place it in the context of the wider fields of magnetism and supramolecular chemistry. All aspects of molecular-based magnets are addressed, including synthesis, structure-property relations and physical properties. Contents include details of the characterization of the first purely organic ferromagnet, the synthesis of high coercivity materials and a unique description of new materials with Curie temperatures well above ambient. A coherent survey of this rapidly developing field for the more general reader, Metal-Organic and Organic Molecular Magnets will also be welcomed by researchers and lecturers in materials science and inorganic or solid state chemistry.
This volume is an outgrowth of the Second International Workshop on Macroscopic Quantum Coherence and Computing held in Napoli, Italy, in June 2000. This workshop gathered a number of experts from the major Universities and Research Institutions of several countries. The choice of the location, which recognizes the role and the traditions of Naples in this field, guaranteed the participants a stimulating atmosphere. The aim of the workshop has been to report on the recent theoretical and experimental results on the macroscopic quantum coherence of macroscopic systems. Particular attention was devoted to Josephson devices. The correlation with other atomic and molecular systems, exhibiting a macroscopic quantum behaviour, was also discussed. The seminars provided both historical overview and recent theoretical ground on the topic, as well as information on new experimental results relative to the quantum computing area. The first workshop on this topic, held in Napoli in 1998, has been ennobled by important reports on observations of Macroscopic Quantum Coherence in mesoscopic systems. The current workshop proposed, among many stimulating results, the first observations of Macroscopic Quantum Coherence between macroscopically distinct fluxoid states in rf SQUIDs, 20 years after the Leggett's proposal to experimentally test the quantum behavior of macroscopic systems. Reports on observations of quantum behaviour in molecular and magnetic systems, small Josephson devices, quantum dots have also been particularly stimulating in view of the realization of several possible q-bits.
The series Structure and Bonding publishes critical reviews on topics of research concerned with chemical structure and bonding. The scope of the series spans the entire Periodic Table and addresses structure and bonding issues associated with all of the elements. It also focuses attention on new and developing areas of modern structural and theoretical chemistry such as nanostructures, molecular electronics, designed molecular solids, surfaces, metal clusters and supramolecular structures. Physical and spectroscopic techniques used to determine, examine and model structures fall within the purview of Structure and Bonding to the extent that the focus is on the scientific results obtained and not on specialist information concerning the techniques themselves. Issues associated with the development of bonding models and generalizations that illuminate the reactivity pathways and rates of chemical processes are also relevant. The individual volumes in the series are thematic. The goal of each volume is to give the reader, whether at a university or in industry, a comprehensive overview of an area where new insights are emerging that are of interest to a larger scientific audience. Thus each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years should be presented using selected examples to illustrate the principles discussed. A description of the physical basis of the experimental techniques that have been used to provide the primary data may also be appropriate, if it has not been covered in detail elsewhere. The coverage need not be exhaustive in data, but should rather be conceptual, concentrating on the new principles being developed that will allow the reader, who is not a specialist in the area covered, to understand the data presented. Discussion of possible future research directions in the area is welcomed. Review articles for the individual volumes are invited by the volume editors. Readership: research scientists at universities or in industry, graduate students Special offer for all customers who have a standing order to the print version of Structure and Bonding, we offer free access to the electronic volumes of the Series published in the current year via SpringerLink.
This book provides an overview of the physical phenomena discovered in magnetic molecular materials over the last 20 years. It is written by leading scientists having made the most important contributions to this active area of research. The main topics of this book are the principles of quantum tunneling and quantum coherence of single-molecule magnets (SMMs), phenomena which go beyond the physics of individual molecules, such as the collective behavior of arrays of SMMs, the physics of one-dimensional single–chain magnets and magnetism of SMMs grafted on substrates. The potential applications of these physical phenomena to classical and quantum information, communication technologies, and the emerging fields of molecular spintronics and magnetic refrigeration are stressed. The book is written for graduate students, researchers and non-experts in this field of research.
The first NATO Advanced Workshop on Quantum Tunneling of Magnetization (QTM) was organized and co-directed by Bernard Barbara, Leon Gunther, Nicolas Garcia, and Anthony Leggett and was held from June, 27 through July 1, 1994 in Grenoble and Chichilianne, France. These Proceedings include twenty-nine articles that represent the contributions of the participants in the Workshop. Quantum Tunneling of Magnetization is not only interesting for purely academic reasons. It was pointed out in the review article by L. Gunther in the December, 1990 issue of Physics World, that QTM may be destined to play a significant role within the next two decades in limiting the density of information storage in magnetic systems. Recent advances have indicated that this limitation may well be reached even earlier than first predicted. Furthermore, the number of people who have entered the field of study of QTM during these past few years has increased many fi)ld. The time was therefore opportune to hold a Workshop to bring together for the first time the leading researchers of QTM, both theoretical and experimental, so as to discuss the current status of the field. The most controversial issue at the time of the Workshop was how to establish r.eliable criteria for determining whether experimental results do indeed reveal manifestations of QTM. We believe that much progress was made at the Workshop on this issue.
Molecular Magnetism: From Molecular Assemblies to the Devices reviews the state of the art in the area. It is organized in two parts, the first of which introduces the basic concepts, theories and physical techniques required for the investigation of the magnetic molecular materials, comparing them with those used in the study of classical magnetic materials. Here the reader will find: (i) a detailed discussion of the electronic processes involved in the magnetic interaction mechanisms of molecular systems, including electron delocalization and spin polarization effects; (ii) a presentation of the available theoretical models based on spin and Hubbard Hamiltonians; and (iii) a description of the specific physical investigative techniques used to characterize the materials. The second part presents the different classes of existing magnetic molecular materials, focusing on the possible synthetic strategies developed to date to assemble the molecular building blocks ranging from purely organic to inorganic materials, as well as on their physical properties and potential applications. These materials comprise inorganic and organic ferro- and ferrimagnets, high nuclearity organic molecules and magnetic and metallic clusters, spin crossover systems, charge transfer salts (including fulleride salts and organic conductors and superconductors), and organized soft media (magnetic liquid crystals and Langmuir-Blodgett films).
En esta tesis se han estudiado los imanes moleculares (SMM o Single Molecule Magnets en inglés) como potenciales candidatos para formar parte del procesador de un ordenador cuántico. En concreto, moléculas compuestas por uno, dos o tres iones que actúan como qubits. Por otro lado, se ha desarrollado una nueva generación de microsusceptómetros SQUID de 30 µm de diámetro que ha permitido estudiar el comportamiento de muestras de tamaño nanométrico como un primer paso para verificar el comportamiento de estos SMM aislados de su medio cristalino.
This text unravels those fundamental physical principles which explain how all matter behaves. It takes us from the foundations of quantum mechanics, through quantum models of atomic, molecular, and electronic structure, and on to discussions of spectroscopy, and the electronic and magnetic properties of molecules.