Download or read book Spin Correlations and Orbital Physics in Vanadates written by Markos Skoulatos and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spin orbital Physics in Transition Metal Oxides written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many body aspect of interplay between spin degrees of freedom and orbital degrees of freedom in transition metal oxides is studied. In this thesis work, I study three major research projects. First, I study SU(2) Heisenberg spin models and discuss some pathologies associated with the Schwinger boson mean field theory for the SU(N) Heisenberg models in which orbital degrees of freedom can be included as an internal symmetry. Second, considering the key parameters realized in the system, I derive an effective superexchange spin-orbital Hamiltonian for the $YVO3̲$ system and use mean field theory to explain the observed high temperature orbital transition and spin transitions. Third, I study the newly proposed spin-2 bond model for insulating $V2̲O3̲$ system. I use Bogolyubov-Peirels variational approach to study the effects of quantum fluctuation and short range spin correlations on magnetic phase transitions. Then, I explin observed large entropy jump and the other experimental observations in the system. Interestingly, with the model of $V2̲O3̲$, I find a novel mechanism for spin ordering and disordering transitions due dimensional crossover and dimensional reduction induced by orbital ordering.
Download or read book Physics of Transition Metal Oxides written by Sadamichi Maekawa and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fact that magnetite (Fe304) was already known in the Greek era as a peculiar mineral is indicative of the long history of transition metal oxides as useful materials. The discovery of high-temperature superconductivity in 1986 has renewed interest in transition metal oxides. High-temperature su perconductors are all cuprates. Why is it? To answer to this question, we must understand the electronic states in the cuprates. Transition metal oxides are also familiar as magnets. They might be found stuck on the door of your kitchen refrigerator. Magnetic materials are valuable not only as magnets but as electronics materials. Manganites have received special attention recently because of their extremely large magnetoresistance, an effect so large that it is called colossal magnetoresistance (CMR). What is the difference between high-temperature superconducting cuprates and CMR manganites? Elements with incomplete d shells in the periodic table are called tran sition elements. Among them, the following eight elements with the atomic numbers from 22 to 29, i. e. , Ti, V, Cr, Mn, Fe, Co, Ni and Cu are the most im portant. These elements make compounds with oxygen and present a variety of properties. High-temperature superconductivity and CMR are examples. Most of the textbooks on magnetism discuss the magnetic properties of transition metal oxides. However, when one studies magnetism using tradi tional textbooks, one finds that the transport properties are not introduced in the initial stages.
Download or read book Spin and Orbital Physics in Insulating Vanadium Oxide written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The transition metal oxide Vanadium Oxide evokes wide ranging research interest due to diverse and complex physical phenomenon it exhibits. The material has a rich phase diagram with four phases that are characterized by remarkably different properties. In recent years, the unique properties and phenomenon observed in the insulating regime of Vanadium Oxide have received a lot of attention. In addition to the long standing issue of the unusual magnetic ordering in the magnetically ordered insulating phase, recent experimental studies including neutron and resonant x-ray scattering, and x-ray absorption studies have raised new, interesting questions of the complex physics of the disordered and magnetically ordered insulating phases and the transition between these phases. In this work we have tried to gain a comprehensive physical understanding of insulating Vanadium Oxide by developing a microscopic S=2 bond model that is based on spin and orbital degrees of freedom, and is consistent with the parameters and phenomenology of this system. We have used this model to study insulating Vanadium Oxide in different temperature and parameter regimes, and thereby tried to elucidate the role played by spin and orbital physics in governing the interesting behavior observed in this system. We find that using the S=2 bond model with spin and orbital degrees of freedom, we can satisfactorily explain not only the anomalous magnetic ordering, but also all the other properties of the disordered and magnetically ordered insulating phases observed by experimental studies. The model also shows a phase transition between these phases which is completely consistent with the phenomenology of the magnetic transition in insulating Vanadium Oxide.
Download or read book Lectures on the Physics of Highly Correlated Electron Systems X written by Adolfo Avella and published by American Institute of Physics. This book was released on 2006-07-19 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains lectures on strongly correlated electron systems presented by eminent physicists. These lectures are up-to-date summaries of relevant subjects in the field of condensed matter physics intended to train students. Contributions include: Strongly correlated electron behaviors and heavy Fermions in anomalous rare-earth and actinide systems; strong correlations in low dimensional systems; functional renormalization group approach to correlated electron systems; and numerical approaches to coupled quantum systems.
Download or read book Contributions to the Theory of Spin Correlations in Electron Gases With Spin Orbit Coupling written by Tobias Hartenstein and published by . This book was released on 2013 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lectures on the Physics of Highly Correlated Electron Systems X written by American Institute of Physics and published by American Institute of Physics. This book was released on 2006-07-19 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains lectures on strongly correlated electron systems presented by eminent physicists. These lectures are up-to-date summaries of relevant subjects in the field of condensed matter physics intended to train students. Contributions include: Strongly correlated electron behaviors and heavy Fermions in anomalous rare-earth and actinide systems; strong correlations in low dimensional systems; functional renormalization group approach to correlated electron systems; and numerical approaches to coupled quantum systems.
Download or read book Progress of Theoretical Physics written by and published by . This book was released on 2005 with total page 1108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Materials for Thermoelectric Applications Theory and Experiment written by Veljko Zlatic and published by Springer. This book was released on 2012-10-17 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric devices could play an important role in making efficient use of our energy resources but their efficiency would need to be increased for their wide scale application. There is a multidisciplinary search for materials with an enhanced thermoelectric responses for use in such devices. This volume covers the latest ideas and developments in this research field, covering topics ranging from the fabrication and characterization of new materials, particularly those with strong electron correlation, use of nanostructured, layered materials and composites, through to theoretical work to gain a deeper understanding of thermoelectric behavior. It should be a useful guide and stimulus to all working in this very topical field.
Download or read book Spin orbit Coupling Effects in Two Dimensional Electron and Hole Systems written by Roland Winkler and published by Springer. This book was released on 2014-03-12 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part provides a general introduction to the electronic structure of quasi-two-dimensional systems with a particular focus on group-theoretical methods. The main part of the monograph is devoted to spin-orbit coupling phenomena at zero and nonzero magnetic fields. Throughout the book, the main focus is on a thorough discussion of the physical ideas and a detailed interpretation of the results. Accurate numerical calculations are complemented by simple and transparent analytical models that capture the important physics.
Download or read book Spin Correlations in Frustrated Magnets with Orbital Ordering written by Andrea Joanne Magee and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spin correlations in frustrated magnets with orbital ordering written by Andrea Magee and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electron and Spin Correlations in Solids written by Ludwik Dobrzyński and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantifying the Importance of Orbital Over Spin Correlations in Delta Pu Within Density functional Theory written by and published by . This book was released on 2007 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin and orbital and electron correlations are known to be important when treating the high-temperature [delta] phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model [delta]-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in [delta]-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of [delta]-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the [delta] phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.
Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 2009 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Properties and Applications of Thermoelectric Materials written by Veljko Zlatic and published by Springer Science & Business Media. This book was released on 2009-06-24 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: As concerns with the efficient use of energy resources, and the minimization of environmental damage have come to the fore, there has been a renewed interest in the role that thermoelectric devices could play in generating electricity from waste heat, enabling cooling via refrigerators with no moving parts, and many other more specialized applications. The main problem in realizing this ambition is the rather low efficiency of such devices for general applications. This book deals with the proceedings of a workshop addressed that problems by reviewing the latest experimental and theoretical work on suitable materials for device applications and by exploring various strategies that might increase their efficiency. The proceedings cover a broad range of approaches, from the experimental work of fabricating new compounds through to theoretical work in characterizing and understanding their properties. The effects of strong electron correlation, disorder, the proximity to metal-insulator transitions, the properties of layered composite materials, and the introduction of voids or cages into the structure to reduce the lattice thermal conductivity are all explored as ways of enhancing the efficiency of their use in thermoelectric devices.
Download or read book Quantum Magnetism written by Bernard Barbara and published by Springer Science & Business Media. This book was released on 2008-06-24 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This bookis based on some of the lectures duringthe Paci?c Institute of Theoretical Physics (PITP) summer school on “Quantum Magnetism”, held during June 2006 in Les Houches, in the French Alps. The school was funded jointly by NATO, the CNRS, and PITP, and entirely organized by PITP. Magnetism is a somewhat peculiar research ?eld. It clearly has a quant- mechanical basis – the microscopic exchange interactions arise entirely from the exclusion principle, in conjunction with repulsive interactions between electrons. And yet until recently the vast majority of magnetism researchersand users of m- netic phenomena around the world paid no attention to these quantum-mechanical roots. Thus, e.g., the huge ($400 billion per annum) industry which manufactures hard discs, and other components in the information technology sector, depends entirely on room-temperature properties of magnets – yet at the macroscopic or mesoscopic scales of interest to this industry, room-temperature magnets behave entirely classically.
