Download or read book Phase Transitions and Self Organization in Electronic and Molecular Networks written by J.C. Phillips and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in nanoscale science show that the properties of many materials are dominated by internal structures. In molecular cases, such as window glass and proteins, these internal structures obviously have a network character. However, in many partly disordered electronic materials, almost all attempts at understanding are based on traditional continuum models. This workshop focuses first on the phase diagrams and phase transitions of materials known to be composed of molecular networks. These phase properties characteristically contain remarkable features, such as intermediate phases that lead to reversibility windows in glass transitions as functions of composition. These features arise as a result of self-organization of the internal structures of the intermediate phases. In the protein case, this self-organization is the basis for protein folding. The second focus is on partly disordered electronic materials whose phase properties exhibit the same remarkable features. In fact, the phenomenon of High Temperature Superconductivity, discovered by Bednorz and Mueller in 1986, and now the subject of 75,000 research papers, also arises from such an intermediate phase. More recently discovered electronic phenomena, such as giant magnetoresistance, also are made possible only by the existence of such special phases. This book gives an overview of the methods and results obtained so far by studying the characteristics and properties of nanoscale self-organized networks. It demonstrates the universality of the network approach over a range of disciplines, from protein folding to the newest electronic materials.
Download or read book Electronic Properties of Doped Semiconductors written by B.I. Shklovskii and published by Springer Science & Business Media. This book was released on 2013-11-09 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: First-generation semiconductors could not be properly termed "doped- they were simply very impure. Uncontrolled impurities hindered the discovery of physical laws, baffling researchers and evoking pessimism and derision in advocates of the burgeoning "pure" physical disciplines. The eventual banish ment of the "dirt" heralded a new era in semiconductor physics, an era that had "purity" as its motto. It was this era that yielded the successes of the 1950s and brought about a new technology of "semiconductor electronics". Experiments with pure crystals provided a powerful stimulus to the develop ment of semiconductor theory. New methods and theories were developed and tested: the effective-mass method for complex bands, the theory of impurity states, and the theory of kinetic phenomena. These developments constitute what is now known as semiconductor phys ics. In the last fifteen years, however, there has been a noticeable shift towards impure semiconductors - a shift which came about because it is precisely the impurities that are essential to a number of major semiconductor devices. Technology needs impure semiconductors, which unlike the first-generation items, are termed "doped" rather than "impure" to indicate that the impurity levels can now be controlled to a certain extent.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1987 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Semiconductor Physics written by Karl W. Böer and published by Springer Nature. This book was released on 2023-02-02 with total page 1408 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook gives a complete and detailed survey of the field of semiconductor physics. It addresses every fundamental principle, the most important research topics and results, as well as conventional and emerging new areas of application. Additionally it provides all essential reference material on crystalline bulk, low-dimensional, and amorphous semiconductors, including valuable data on their optical, transport, and dynamic properties. This updated and extended second edition includes essential coverage of rapidly advancing areas in semiconductor physics, such as topological insulators, quantum optics, magnetic nanostructures and spintronic systems. Richly illustrated and authored by a duo of internationally acclaimed experts in solar energy and semiconductor physics, this handbook delivers in-depth treatment of the field, reflecting a combined experience spanning several decades as both researchers and educators. Offering a unique perspective on many issues, Semiconductor Physics is an invaluable reference for physicists, materials scientists and engineers throughout academia and industry.
Download or read book Amorphous and Liquid Semiconductors written by M. H. Cohen and published by Elsevier Science & Technology. This book was released on 1972 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Foundations of Solid State Devices written by E. Fred Schubert and published by E. Fred Schubert. This book was released on 2022-02-22 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is beneficial for technical personnel working in the field of microelectronics, optoelectronics, and photonics to get a good understanding of the physical foundations of modern semiconductor devices. Questions that technical personnel may ask are: How are electrons propagating in the periodic potential of a crystal lattice? What are the foundations of semiconductor heterostructure devices? How does quantum mechanics relate to semiconductor heterostructures? This book tries to answer questions such as these. The book provides a basis for the understanding of modern semiconductor devices that have dimensions in the nanometer range, that is, comparable to the electron de Broglie wavelength. For such small spatial dimensions, classical physics no longer gives a full description of physical processes. The inclusion of quantum mechanical principles becomes mandatory and provides a useful description of common physical processes in electronic, optoelectronic, and photonic devices. Chapters 1 to 11 teach the quantum‐mechanical principles, including the postulates of quantum mechanics, operators, the uncertainty principle, the Schrödinger equation, non‐periodic and periodic potentials, quantum wells, and perturbation theory. Chapters 12 to 20 apply these principles to semiconductor devices and discuss the density of states, semiconductor statistics, carrier concentrations, doping, tunneling, and aspects of heterostructure devices. The 2022 edition is a complete revision of the 2015 edition and also updates the formatting to make it easily viewable with electronic display devices.
Download or read book Noncrystalline Semiconductors written by and published by . This book was released on 1987 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summaries of Projects Completed written by National Science Foundation (U.S.) and published by . This book was released on with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summaries of Projects Completed in Fiscal Year written by National Science Foundation (U.S.) and published by . This book was released on 1977 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summaries of Projects Completed in Fiscal Year written by and published by . This book was released on with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Properties Research Literature Retrieval Guide 1972 1976 Elements written by Purdue University. Center for Information and Numerical Data Analysis and Synthesis and published by Ifi/Plenum. This book was released on 1979 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Digest of Literature on Dielectrics written by and published by National Academies. This book was released on 1977 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semiconductor Physics written by Владимир Максимович Тучкевич and published by Springer. This book was released on 1986-09-30 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Current Technical Papers written by and published by . This book was released on 1974 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic transitions and correlation effects written by Johan Jönsson and published by Linköping University Electronic Press. This book was released on 2020-03-17 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Macroscopic properties of real materials, such as conductivity, magneticproperties, crystal structure parameters, etc. are closely related or evendetermined by the configuration of their electrons, characterized by electronicstructure. By changing the conditions, e.g, pressure, temperature, magnetic/electric field, chemical doping, etc. one can modify the electronic structure ofsolids and therefore induce a phase transition(s) between different electronic andmagnetic states. One famous example is a Mott metal-to-insulator phase transition,at which a material undergoes a significant, often many orders of magnitude, changeof conductivity caused by the interplay between itineracy and localization of thecarriers. Electronic topological transitions (ETT) involvechanges in the topology of a metal's Fermi surface. This thesis investigates theeffect of such electronic transitions in various materials, ranging from pureelements to complex compounds. To describe the interplay between electronic transitionsand properties of real materials,different state-of-the-art computational methods are used. The densityfunctional theory(DFT), as well as the DFT + U method, is used to calculatestructural properties. The validity of recently introduced exchange-correlationfunctionals, such as the strongly constrained and appropriately normed (SCAN)functional, is also assessed for magnetic elements. In order toinclude dynamical effects of electron interactions we use the DFT + dynamical meanfield theory (DFT + DMFT) method. Experiments in hcp-Os have reported peculiarities in the ratio betweenlattice parameters at high pressure. Previous calculations have suggested these transitions maybe related to ETTs and even crossings of core levels at ultra high pressure. Inthis thesis it is shownthat the crossing of core levels is a general feature of heavy transitionmetals. Experiments have therefore been performed to look for indications ofthis transition in Ir using X-ray absorption spectroscopy. In NiO, strongrepulsion between electrons leads to a Mott insulating state at ambientconditions. It has long been predicted that high pressure will lead to aninsulator-to-metal transition. This has been suggested to be accompanied by aloss of magnetic order, and a structural phase transition. In collaboration withexperimentalists we look for thistransition by investigating the X-ray absorption spectra as well as themagnetic hyperfine field. We find no evidence of a Mott transition up to 280GPa. In the Mott insulator TiPO4, application of external pressure has beensuggested to lead to a spin-Peierls transition at room temperature. Weinvestigate the dimerisation and the magnetic structure of TiPO4 at high pressure.As pressure is increased further, TiPO4 goes through a metal to insulatortransition before an eventual crystallographic phase transition. Remarkably, thenew high pressure phases are found to be insulators; the Mott insulating stateis restored. MAX phases are layered materials that combinemetallic and ceramic properties and feature layers of M-metal and X-C or N atomsinterconnected by A-group atoms. Magnetic MAX-phases with their low dimensionalmagnetism are promising candidates for applications in e.g., spintronics.The validity of various theoretical approaches are discussed in connection tothe magnetic MAX-phase Mn2GaC. Using DFT and DFT + DMFT we consider the hightemperature paramagnetic state, and whether the magnetic moments are formed bylocalized or itinerant electrons. Ett materials makroskopiska egenskaper, såsom ledningsförmåga, magnetiska egenskaper, kristallstrukturparametrar, etc. är relaterade till, eller till och med bestämda av elektronernas konfiguration, vilken karakteriseras av elektronstrukturen. Genom att ändra förhållandena, till exempel via tryck, temperatur, magnetiska och/eller elektriska fält, dopning, etc. är det möjligt att modifiera elektronstrukturen hos ett material, och därigenom inducera fasövergångar mellan olika magnetiska och elektron-tillstånd. Mott metall-till-isolator övergången är ett berömt exempel på en fasövergång, då ett material genomgår en omfattande, ofta flera tiopotenser, förändring i ledningsförmåga, orsakad av samspelet mellan ambulerande och lokaliserade laddningsbärare. Vid en elektronisk-topologisk övergång (eng. electronic topological transition, ETT) sker förändringar i elektronernas energifördelning vilket modifierar materialets Fermi-yta. I den här avhandlingen undersöks dylika övergångar i olika material, från rena grundämnen till komplicerade föreningar. Flera olika toppmoderna beräkningsmetoder används för att redogöra för samspelet mellan elektroniska fasövergångar och egenskaper hos riktiga material. Täthetsfunktionalterori (eng. density functional theory, DFT), samt DFT + U, har används för att beräkna strukturella egenskaper. Lämplighetsgraden i att använda nyligen publicerade exchangecorrelation- funktionaler, såsom SCAN (eng. strongly constrained and appropriately normed), för att beskriva magnetiska grundämnen undersöks även. För att inkludera dynamiska elektronkorrelationer använder vi metoden DFT + dynamisk medelfältteori (eng. dynamical mean field theory, DMFT). Experiment utförda på hcp-Os vid högt tryck visar underliga hopp i kvoten mellan gitterparametrar. Tidigare beräkningar har indikerat att dessa övergångar kan vara relaterade till elektronisk-topologiska övergångar och korsande av kärntillstånd. I den här avhandlingen visas också att korsning av kärntillstånden är en generell egenskap hos tunga övergångsmetaller. Därför utförs röntgenabsorptionsexperiment på Ir för att leta efter tecken på denna typ av övergång. Övergångsmetalloxiden NiO har sedan länge förutspåtts genomgå en isolator till metall Mott-övergång. Det har föreslagits att denna övergång sker vid höga tryck i samband med att materialets magnetiska ordning försvinner och en strukturell övergång sker. I samarbete med experimentalister letar vi efter denna övergång genom att studera röntgenabsorptionsspektra och det magnetiska hyperfina fältet. Vi ser inga indikationer på en Mott-övegång, upp till ett tryck på 280 GPa. Det har föreslagits att Mott-isolatorn TiPO4 genomgår en så kallad spin-Peierls-övergång, vid rumstemperatur, när tryck appliceras. Vi undersöker dimeriseringen och den magnetiska strukturen i TiPO4 som funktion av tryck. Vid höga tryck genomgår TiPO4 ytterligare övergångar, från en isolerande till en metallisk fas för att slutligen genomgå en strukturell övergång. De nya högtrycksfaserna visar sig anmärkningsvärt vara Mott-isolatorer. MAX-faser är en grupp material med specifik kristallstruktur, som kombinerar egenskaper från keramiska material och metaller. En MAX-fas består av lager av M –metall-atomer – och X – kol- eller kväveatomer – vilka sammanbinds av atomer från grupp A. Magnetiska MAX-faser som visar magnetiska egenskaper, liknande de för lågdimensionella material, är lovande kandidater för applikation inom exempelvis spinntronik. Den här avhandlingen undersöker lämplighetsgraden i att använda diverse teoretiska metoder för att beskriva magnetiska MAX-faser. Med hjälp av DFT och DFT + DMFT undersöker vi den paramagnetiska högtemperaturfasen och huruvida de magnetiska momenten bildas av lokaliserade eller ambulerande elektroner.
Download or read book Cumulative Author Index of the Physical Review and Physical Review Letters written by and published by . This book was released on 1970 with total page 780 pages. Available in PDF, EPUB and Kindle. Book excerpt:
