Download or read book Mean field and Density functional Studies of Charge Ordering and Magnetic Transitions in Lanthanum Manganites written by Snigdharaj Kumar Mishra and published by . This book was released on 1997 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Manganese oxides with perovskite structure exhibit many interesting properties. Recently colossal magnetoresistance (CMR) was observed in these oxides. They show extremely large change in electrical resistance in response to applied magnetic fields. This property has lots of technological relevance for the development of magnetic memory and switching devices. These oxides also show transitions from antiferromagnet to ferromagnet coupled with charge-order to charge-nonorder transition. In this dissertation we examine the electronic origin of these phenomena of lanthanum manganites by studying a model electronic Hamiltonian, which includes double-exchange, super-exchange, and Hubbard terms, using a combination of Hartree-Fock approximation and an exact diagonalization scheme. The existence of "canted" spin order is investigated at zero temperature. We find that the double-exchange mechanism does not always lead to a canted magnetic state, even for small carrier concentration. The canting may be suppressed in these compounds for the typical electronic parameters. We study the charge ordering and magnetic transitions in the perovskites by solving the Hamiltonian both at zero and finite temperature. At zero temperature as we increase the strength of the extended-Hubbard repulsion $(U\sb1), $ a first-order transition from a charge-non-ordered metallic ferromagnet (FN) to a charge-ordered, insulating antiferromagnet (AFO) is obtained. The AFO-FN transition is also obtained by increasing the temperature T. The melting of charge ordering as a function of temperature, doping concentration and magnetic field is also examined. Different phases are obtained as a function of temperature and doping concentration. These are in qualitative agreement with experimental data. We study the electronic structures of pyrochlores by the density-functional LMTO method and show that the double-exchange mechanism is relevant for these compounds as well.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1999 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of Manganites written by T.A. Kaplan and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involves chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up to date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M. F. Thorpe, Series Editor E mail: thorpe@pa. msu. edu V PREFACE This book records invited lectures given at the workshop on Physics of Manganites, held at Michigan State University, July 26 29, 1998. Doped manganites are an interesting class of compounds that show both metal insulator and ferromagnetic to paramagnetic transitions at the same temperature. This was discovered in the early 1950s by Jonker and van Santen and basic theoretical ideas were developed by Zener (1951), Anderson and Hasegawa (1955), and deGennes (1960) to explain these transitions and related interesting observations.
Download or read book Colossal Magnetoresistive Manganites written by Tapan Chatterji and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physics of transition metal oxides has become a central topic of interest to condensed-matter scientists ever since high temperature superconductivity was discovered in hole-doped cuprates with perovskite-like structures. Although the renewed interest in hole-doped perovskite manganites following the discovery of their colossal magnetoresistance (CMR) properties, began in 1993 about a decade after the discovery of high temperature superconductivity, their first investigation started as early as 1950 and basic theoretical ideas were developed during 1951-1960. Experience in sample preparation and characterization, and in growth of single crystals and epitaxial thin films, gained during the research on high temperature superconductors, and the development of theoretical tools, were very efficiently used in research on CMR manganites. In early nineties it appeared to many condensed matter physicists that although the problem of high temperature superconductivity is a difficult one to solve, a quantitative understanding of CMR phenomena might be well within reach. This book is intended to be an account of the latest developments in the phys ics of CMR manganites. When I planned this book back in 2000, I thought that research on the physics of CMR manganites would be more or less consolidated by the time this would be published. I was obviously very optimistic indeed. We are now in 2003 and we still do not have a quantitative understanding of the central CMR effect. Meanwhile the field has expanded. It is still a very active field of research on both the experimental and theoretical fronts.
Download or read book Ceramic Abstracts written by and published by . This book was released on 1998 with total page 1040 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Colossal Magnetoresistance Charge Ordering and Related Properties of Manganese Oxides written by Chintamani Nagesa Ramachandra Rao and published by World Scientific. This book was released on 1998 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal oxides constitute one of the most amazing classes of materials with a wide range of properties. They exhibit a variety of phenomena, such as ferroelectricity, ferromagnetism and superconductivity. A new aspect of metal oxides -- colossal magnetoresistance exhibited by certain manganese oxides, in particular rare earth manganates of perovskite structure -- has received much attention in the last four years. Some of these oxides show 100% magnetoresistance and have much potential for technological applications. Previously this phenomenon was found only in layered and granular metallic materials. Studies of colossal magnetoresistance have led to the discovery of many other new phenomena and properties such as charge ordering and orbital ordering. In view of the importance of colossal magnetoresistance, charge ordering and related phenomena exhibited by oxides to the physics and chemistry of solid materials, it is necessary and timely to have a book dealing with these topics. This book begins with a review of the subject followed by contributions from a number of experts which cover the present status of the subject.
Download or read book Journal of the Physical Society of Japan written by Nihon Butsuri Gakkai and published by . This book was released on 1998 with total page 1178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spin Waves and Magnetic Excitations written by and published by Elsevier. This book was released on 2012-12-02 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern Problems in Condensed Matter Sciences, Volume 22.1: Spin Waves and Magnetic Excitations, Part I focuses on the principles, methodologies, approaches, and reactions involved in spin waves and magnetic excitations, including, Brillouin-Mandelstam light scattering, optical magnetic excitations, and magnetic dielectrics. The selection first elaborates on spin waves in magnetic dielectrics current status of the theory and light scattering from spin waves. Discussions focus on magneto-optic effects and the mechanism of light scattering in magnets, Brillouin-Mandelstam light scattering, Raman scattering, Collinear Heisenberg ferromagnet, low-temperature phase transitions, and low-dimensional systems. The text then ponders on optical magnetic excitations, spin waves above the threshold of parametric excitations, and theory of spin excitations in rare earth systems. Topics include Hamiltonian for rare earth systems, parametric instability of spin waves in magnetic dielectrics, nonstationary processes in parametric excitation of spin waves, radiative decay of magnetic excitons, and mechanism of the generation of magnetic excitations by light. The book tackles 4f moments and their interaction with conduction electrons and neutron scattering studies of magnetic excitations in itinerant magnets, including magnetic excitations at finite and low temperatures, paramagnetic scattering, coupling to conduction electrons, and virtual magnetic excitations. The selection is highly recommended for researchers wanting to study spin waves and magnetic excitations.
Download or read book Spectroscopy of Complex Oxide Interfaces written by Claudia Cancellieri and published by Springer. This book was released on 2018-04-09 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the most recent and compelling experimental results for complex oxide interfaces. The results of this book were obtained with the cutting-edge photoemission technique at highest energy resolution. Due to their fascinating properties for new-generation electronic devices and the challenge of investigating buried regions, the book chiefly focuses on complex oxide interfaces. The crucial feature of exploring buried interfaces is the use of soft X-ray angle-resolved photoemission spectroscopy (ARPES) operating on the energy range of a few hundred eV to increase the photoelectron mean free path, enabling the photons to penetrate through the top layers – in contrast to conventional ultraviolet (UV)-ARPES techniques. The results presented here, achieved by different research groups around the world, are summarized in a clearly structured way and discussed in comparison with other photoemission spectroscopy techniques and other oxide materials. They are complemented and supported by the most recent theoretical calculations as well as results of complementary experimental techniques including electron transport and inelastic resonant X-ray scattering.
Download or read book The Engineering Index Annual written by and published by . This book was released on 1989 with total page 2152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.
Download or read book Holographic Duality in Condensed Matter Physics written by Jan Zaanen and published by Cambridge University Press. This book was released on 2015-11-05 with total page 587 pages. Available in PDF, EPUB and Kindle. Book excerpt: A pioneering treatise presenting how the mathematical techniques of holographic duality can unify the fundamental theories of physics.
Download or read book Spintronics written by Jean-Philippe Ansermet and published by CRC Press. This book was released on 2024-08-13 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sound understanding of magnetism, transport theory, spin relaxation mechanisms, and magnetization dynamics is necessary to engage in spintronics research. In this primer, special effort has been made to give straightforward explanations for these advanced concepts. This book will be a valuable resource for graduate students in spintronics and related fields. Concepts of magnetism such as exchange interaction, spin-orbit coupling, spin canting, and magnetic anisotropy are introduced. Spin-dependent transport is described using both thermodynamics and Boltzmann’s equation, including Berry curvature corrections. Spin relaxation phenomenology is accounted for with master equations for quantum spin systems coupled to a bath. Magnetic resonance principles are applied to describe spin waves in ferromagnets, cavity-mode coupling in antiferromagnets, and coherence phenomena relevant to spin qubits applications. Key Features: • A pedagogical approach to foundational concepts in spintronics with simple models that can be calculated to enhance understanding. • Nineteen chapters, each beginning with a historical perspective and ending with an outlook on current research. • 1200 references, ranging from landmark papers to frontline publications. Jean-Philippe Ansermet is Professor Emeritus at École Polytechnique Fédérale de Lausanne (EPFL), where he pioneered experiments on giant magnetoresistance, current-induced magnetization switching, heat-driven spin torque, and nuclear magnetic resonance. He taught mechanics, thermodynamics, and spin dynamics for more than twenty years. A fellow of the American Physical Society and recipient of the 2022 Credit Suisse Teaching Award, he was an executive board member of the European Physical Society, president of the Swiss Physical Society, and teaching director at EPFL. He has authored or co-authored textbooks on mechanics and thermodynamics and published more than two hundred articles.
Download or read book Magnetism written by Joel S. Miller and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combining the contemporary knowledge from widely scattered sources, this is a much-needed and comprehensive overview of the field. In maintaining a balance between theory and experiment, the book guides both advanced students and specialists to this research area. Topical reviews written by the foremost scientists explain recent trends and advances, focusing on the correlations between electronic structure and magnetic properties. The book spans recent trends in magnetism for molecules -- as well as inorganic-based materials, with an emphasis on new phenomena being explored from both experimental and theoretical viewpoints with the aim of understanding magnetism on the atomic scale. The volume helps readers evaluate their own experimental observations and serves as a basis for the design of new magnetic materials. Topics covered include: * Metallocenium Salts of Radical Anion Bis-(dichalcogenate) metalates * Chiral Molecule-Based Magnets * Cooperative Magnetic Behavior in Metal-Dicyanamide Complexes * Lanthanide Ions in Molecular Exchange Coupled Systems * Monte Carlo Simulation * Metallocene-Based Magnets * Magnetic Nanoporous Molecular Materials A unique reference work, indispensable for everyone concerned with the phenomena of magnetism.
Download or read book Frontiers in Crystalline Matter written by National Research Council and published by National Academies Press. This book was released on 2009-10-27 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: For much of the past 60 years, the U.S. research community dominated the discovery of new crystalline materials and the growth of large single crystals, placing the country at the forefront of fundamental advances in condensed-matter sciences and fueling the development of many of the new technologies at the core of U.S. economic growth. The opportunities offered by future developments in this field remain as promising as the achievements of the past. However, the past 20 years have seen a substantial deterioration in the United States' capability to pursue those opportunities at a time when several European and Asian countries have significantly increased investments in developing their own capacities in these areas. This book seeks both to set out the challenges and opportunities facing those who discover new crystalline materials and grow large crystals and to chart a way for the United States to reinvigorate its efforts and thereby return to a position of leadership in this field.
Download or read book High temperature Solid Oxide Fuel Cells Fundamentals Design and Applications written by S.C. Singhal and published by Elsevier. This book was released on 2003-12-08 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications provides a comprehensive discussion of solid oxide fuel cells (SOFCs). SOFCs are the most efficient devices for the electrochemical conversion of chemical energy of hydrocarbon fuels into electricity, and have been gaining increasing attention for clean and efficient distributed power generation. The book explains the operating principle, cell component materials, cell and stack designs and fabrication processes, cell and stack performance, and applications of SOFCs. Individual chapters are written by internationally renowned authors in their respective fields, and the text is supplemented by a large number of references for further information. The book is primarily intended for use by researchers, engineers, and other technical people working in the field of SOFCs. Even though the technology is advancing at a very rapid pace, the information contained in most of the chapters is fundamental enough for the book to be useful even as a text for SOFC technology at the graduate level.
Download or read book Disorder and Strain Induced Complexity in Functional Materials written by Tomoyuki Kakeshita and published by Springer Science & Business Media. This book was released on 2011-10-27 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together an emerging consensus on our understanding of the complex functional materials including ferroics, perovskites, multiferroics, CMR and high-temperature superconductors. The common theme is the existence of many competing ground states and frustration as a collusion of spin, charge, orbital and lattice degrees of freedom in the presence of disorder and (both dipolar and elastic) long-range forces. An important consequence of the complex unit cell and the competing interactions is that the emergent materials properties are very sensitive to external fields thus rendering these materials with highly desirable, technologically important applications enabled by cross-response.
Download or read book Perovskite Oxide for Solid Oxide Fuel Cells written by Tatsumi Ishihara and published by Springer Science & Business Media. This book was released on 2009-06-12 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cell technology is quite promising for conversion of chemical energy of hydrocarbon fuels into electricity without forming air pollutants. There are several types of fuel cells: polymer electrolyte fuel cell (PEFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid oxide fuel cell (SOFC), and alkaline fuel cell (AFC). Among these, SOFCs are the most efficient and have various advantages such as flexibility in fuel, high reliability, simple balance of plant (BOP), and a long history. Therefore, SOFC technology is attracting much attention as a power plant and is now close to marketing as a combined heat and power generation system. From the beginning of SOFC development, many perovskite oxides have been used for SOFC components; for example, LaMnO -based oxide for the cathode and 3 LaCrO for the interconnect are the most well known materials for SOFCs. The 3 current SOFCs operate at temperatures higher than 1073 K. However, lowering the operating temperature of SOFCs is an important goal for further SOFC development. Reliability, durability, and stability of the SOFCs could be greatly improved by decreasing their operating temperature. In addition, a lower operating temperature is also beneficial for shortening the startup time and decreasing energy loss from heat radiation. For this purpose, faster oxide ion conductors are required to replace the conventional Y O -stabilized ZrO 2 3 2 electrolyte. A new class of electrolytes such as LaGaO is considered to be 3 highly useful for intermediate-temperature SOFCs.
