Origin of Spin Gapless Semiconductor Behavior in CoFeCrGa PDF Download
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Author:
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Languages : en
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Book Description
Despite a plethora of materials suggested for spintronic applications, a new class of materials has emerged, namely spin gapless semiconductors (SGS), which offers potentially more advantageous properties than existing ones. These magnetic semiconductors exhibit a finite band gap for one spin channel and a closed gap for the other. Supported by electronic-structure calculations, we report evidence of SGS behavior in equiatomic quaternary CoFeCrGa, having a cubic Heusler (prototype LiMgPdSn) structure but exhibiting chemical disorder (DO3 structure). CoFeCrGa is found to transform from SGS to half-metallic phase under pressure, which is attributed to unique electronic-structure features. The saturation magnetization (MS) was obtained at 8K agrees with the Slater-Pauling rule and the Curie temperature (TC) is found to exceed 400K. Carrier concentration (up to 250K) and electrical conductivity are observed to be nearly temperature independent, prerequisites for SGS. The anomalous Hall coefficient is estimated to be 185S/cm at 5K. Considering the SGS properties and high TC, this material appears to be promising for spintronic applications.
Author:
Publisher:
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Category :
Languages : en
Pages :
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Book Description
Despite a plethora of materials suggested for spintronic applications, a new class of materials has emerged, namely spin gapless semiconductors (SGS), which offers potentially more advantageous properties than existing ones. These magnetic semiconductors exhibit a finite band gap for one spin channel and a closed gap for the other. Supported by electronic-structure calculations, we report evidence of SGS behavior in equiatomic quaternary CoFeCrGa, having a cubic Heusler (prototype LiMgPdSn) structure but exhibiting chemical disorder (DO3 structure). CoFeCrGa is found to transform from SGS to half-metallic phase under pressure, which is attributed to unique electronic-structure features. The saturation magnetization (MS) was obtained at 8K agrees with the Slater-Pauling rule and the Curie temperature (TC) is found to exceed 400K. Carrier concentration (up to 250K) and electrical conductivity are observed to be nearly temperature independent, prerequisites for SGS. The anomalous Hall coefficient is estimated to be 185S/cm at 5K. Considering the SGS properties and high TC, this material appears to be promising for spintronic applications.
Author: Xiaotian Wang
Publisher: MDPI
ISBN: 3038979767
Category : Science
Languages : en
Pages : 152
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Book Description
As we all know, electrons carry both charge and spin. The processing of information in conventional electronic devices is based only on the charge of electrons. Spin electronics, or spintronics, uses the spin of electrons, as well as their charge, to process information. Metals, semiconductors, and insulators are the basic materials that constitute the components of electronic devices, and these types of materials have been transforming all aspects of society for over a century. In contrast, magnetic metals, half-metals (including zero-gap half-metals), magnetic semiconductors (including spin-gapless semiconductors), dilute magnetic semiconductors, and magnetic insulators are the materials that will form the basis for spintronic devices. This book aims to collect a range of papers on novel materials that have intriguing physical properties and numerous potential practical applications in spintronics.
Author: Claudia Felser
Publisher: Springer
ISBN: 3319214497
Category : Technology & Engineering
Languages : en
Pages : 492
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Book Description
This book gives an overview of the physics of Heusler compounds ranging from fundamental properties of these alloys to their applications. Especially Heusler compounds as half-metallic ferromagnetic and topological insulators are important in condensed matter science due to their potential in magnetism and as materials for energy conversion. The book is written by world-leaders in this field. It offers an ideal reference to researchers at any level.
Author: Eberhard Engel
Publisher: Springer Science & Business Media
ISBN: 3642140904
Category : Science
Languages : en
Pages : 543
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Book Description
Density Functional Theory (DFT) has firmly established itself as the workhorse for atomic-level simulations of condensed phases, pure or composite materials and quantum chemical systems. This work offers a rigorous and detailed introduction to the foundations of this theory, up to and including such advanced topics as orbital-dependent functionals as well as both time-dependent and relativistic DFT. Given the many ramifications of contemporary DFT, the text concentrates on the self-contained presentation of the basics of the most widely used DFT variants: this implies a thorough discussion of the corresponding existence theorems and effective single particle equations, as well as of key approximations utilized in implementations. The formal results are complemented by selected quantitative results, which primarily aim at illustrating the strengths and weaknesses of particular approaches or functionals. The structure and content of this book allow a tutorial and modular self-study approach: the reader will find that all concepts of many-body theory which are indispensable for the discussion of DFT - such as the single-particle Green's function or response functions - are introduced step by step, along with the actual DFT material. The same applies to basic notions of solid state theory, such as the Fermi surface of inhomogeneous, interacting systems. In fact, even the language of second quantization is introduced systematically in an Appendix for readers without formal training in many-body theory.
Author: Sadamichi Maekawa
Publisher: Oxford University Press
ISBN: 0198787073
Category : Science
Languages : en
Pages : 541
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Book Description
In a new branch of physics and technology, called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. This book is intended to provide an introduction and guide to the new physics and applications of spin current.
Author: John F. Dobson
Publisher: Springer Science & Business Media
ISBN: 148990316X
Category : Science
Languages : en
Pages : 384
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Book Description
This book is an outcome of the International Workshop on Electronic Density Functional Theory, held at Griffith University in Brisbane, Australia, in July 1996. Density functional theory, standing as it does at the boundary between the disciplines of physics, chemistry, and materials science, is a great mixer. Invited experts from North America, Europe, and Australia mingled with students from several disciplines, rapidly taking up the informal style for which Australia is famous. A list of participants is given at the end of the book. Density functional theory (DFT) is a subtle approach to the very difficult problem of predicting the behavior of many interacting particles. A major application is the study of many-electron systems. This was the workshop theme, embracing inter alia computational chemistry and condensed matter physics. DFT circumvents the more conceptually straightforward (but more computationally intensive) approach in which one solves the many-body Schrodinger equation. It relies instead on rather delicate considerations involving the electron number density. For many years the pioneering work of Kohn and Sham (the Local Density Ap proximation of 1965 and immediate extensions) represented the state of the art in DFT. This approach was widely used for its appealing simplicity and computability, but gave rather modest accuracy. In the last few years there has been a renaissance of interest, quite largely due to the remarkable success of the new generation of gradient functionals whose initiators include invitees to the workshop (Perdew, Parr, Yang).
Author: Claudia Felser
Publisher: Springer Science & Business Media
ISBN: 9048138329
Category : Technology & Engineering
Languages : en
Pages : 379
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Book Description
Spintronics is an emerging technology exploiting the spin degree of freedom and has proved to be very promising for new types of fast electronic devices. Amongst the anticipated advantages of spintronics technologies, researchers have identified the non-volatile storage of data with high density and low energy consumption as particularly relevant. This monograph examines the concept of half-metallic compounds perspectives to obtain novel solutions and discusses several oxides such as perovskites, double perovskites and CrO2 as well as Heusler compounds. Such materials can be designed and made with high spin polarization and, especially in the case of Heusler compounds, many material-related problems present in current-day 3d metal systems, can be overcome. Spintronics: From Materials to Devices provides an insight into the current research on Heusler compounds and offers a general understanding of structure–property relationships, including the influence of disorder and correlations on the electronic structure and interfaces. Spintronics devices such as magnetic tunnel junctions (MTJs) and giant magnetoresistance (GMR) devices, with current perpendicular to the plane, in which Co2 based Heusler compounds are used as new electrode materials, are also introduced. From materials design by theoretical methods and the preparation and properties of the materials to the production of thin films and devices, this monograph represents a valuable guide to both novices and experts in the fields of Chemistry, Physics, and Materials Science.
Author: J. Tsidilkovski
Publisher: Springer Science & Business Media
ISBN: 364260403X
Category : Technology & Engineering
Languages : en
Pages : 259
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Book Description
A presentation of the peculiarities of the physical properties of a comparatively new class of solids. GSs are of practical interest since they are very sensitive to impurities, and to the influence of light, magnetic and electric fields, and to pressure.
Author: Surender Kumar Sharma
Publisher: CRC Press
ISBN: 1351230913
Category : Science
Languages : en
Pages : 326
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Book Description
This timely book covers basic mechanisms, characterization, theoretical simulations, and applications for exchange bias in granular nanosystems, thin films, and bulk systems. After an overview of the field and key principles, the next section covers nanogranular (core-shell) systems, followed by chapters on thin films, bilayers/multilayers nanostructures, dilute magnetic semiconductors, and multiferroic systems. A final section turns to bulk systems, such as those consisting of perovskite structures, rare earth-transition metal intermetallic, and ion implantations. Readers of this book will obtain A complete, modern overview on exchange bias phenomena, covering synthesis, characterization techniques, and applications An introduction to all the important phenomenological models proposed for thin films, bulk materials, and nanoparticles Detailed discussion of the importance of size, shape, cooling field, and temperature on exchange bias properties Understanding of novel applications of exchange bias systems
Author: S. G. Dani
Publisher: Springer Nature
ISBN: 9811506833
Category : Mathematics
Languages : en
Pages : 176
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Book Description
This book gathers papers on recent advances in the ergodic theory of group actions on homogeneous spaces and on geometrically finite hyperbolic manifolds presented at the workshop “Geometric and Ergodic Aspects of Group Actions,” organized by the Tata Institute of Fundamental Research, Mumbai, India, in 2018. Written by eminent scientists, and providing clear, detailed accounts of various topics at the interface of ergodic theory, the theory of homogeneous dynamics, and the geometry of hyperbolic surfaces, the book is a valuable resource for researchers and advanced graduate students in mathematics.
