Spintronics is a newly developing area in the field of magnetism, in which the interplay of magnetism and transport phenomena is studied experimentally and theoretically. This book introduces the recent progresses in the research relating to spintronics. * Presents in-depth analysis of this fascinating and technologically important new branch of nanoscience * Edited text with contributions from acknowledged leaders in the field * This handbook and guide will appeal to students and researchers in the fields of electronic devices and materials
Nanomagnetism and spintronics are two close subfields of nanoscience, explaining the effect of substantial magnetic properties of matter when the materials fabrication is realized at a comparable length size. Nanomagnetism deals with the magnetic phenomena specific to the structures having dimensions in the submicron range. The fact that the electronic transport properties of materials are dependent on the magnetic properties' artificial nanostructures, i.e., giant magnetoresistance (GMR) or tunneling magnetoresistance (TMR), has revolutionized spintronics science and technology. This book explains the concepts of nanomagnetism and spintronics by viewing the most recent research works from internationally distinguished research groups. Placing special emphasis on crucial fundamental and technical aspects of nanomagnetism and spintronics, it serves as a one-stop reference for universities offering postgraduate programs in nanotechnology or related disciplines. This unique book deals with all three stages required for conducting research in nanomagnetism and spintronics including fabrication, characterization and applications of nanomagnetic and spintronics materials, providing general concepts and an insightful overview of this subject for research students and scientists from different backgrounds investigating the multidisciplinary area of nanotechnology.
The concise and accessible chapters of Nanomagnetism and Spintronics, Second Edition, cover the most recent research in areas of spin-current generation, spin-calorimetric effect, voltage effects on magnetic properties, spin-injection phenomena, giant magnetoresistance (GMR), and tunnel magnetoresistance (TMR). Spintronics is a cutting-edge area in the field of magnetism that studies the interplay of magnetism and transport phenomena, demonstrating how electrons not only have charge but also spin. This second edition provides the background to understand this novel physical phenomenon and focuses on the most recent developments and research relating to spintronics. This exciting new edition is an essential resource for graduate students, researchers, and professionals in industry who want to understand the concepts of spintronics, and keep up with recent research, all in one volume. Provides a concise, thorough evaluation of current research Surveys the important findings up to 2012 Examines the future of devices and the importance of spin current
Current and voltage applied to the magnetic nanopillars induce a spin injection and an accumulation of nonequilibrium charges in a nanosize magnetic cell and result a spin torque exerted on the magnetic moment. Using such torques, we may amplify a precession of magnetization and induct a magnetization switching. These phenomena provide new techniques to write information into tiny magnetic cells and to construct oscillators and rectifiers that are several tens of nanometers in size. In this chapter, spin injections, and current and voltage-induced spin torques in magnetic multilayers, which show giant magnetoresistance effect in current-perpendicular-to-plane (CPP-GMR) geometry, and magnetic tunneling junctions are described. Further, mechanisms of spin injection and voltage-induced magnetization switching and its high-speed observations are explained. Then, phenomena related to spin injection, namely, spin-transfer oscillation and the spin-torque diode effect, are described. Finally, applications related to the spin-injection technology are reviewed.
Novel magnetotransport phenomena appear when magnet sizes become nanoscale. Typical examples of such phenomena are giant magnetoresistance (GMR) in magnetic multilayers, tunnel magnetoresistance (TMR) in ferromagnetic tunnel junctions, and ballistic magnetoresistance (BMR) in magnetic nanocontacts. In this chapter, we first briefly review the relationship between spin-dependent resistivity and electronic structures in metals and alloys, and describe microscopic methods for investigating electrical transport. We then review the essential aspects of GMR, TMR, and BMR, emphasizing the role of the electronic structures of the constituent metals of these junctions and the effects of roughness on the electrical resistivity (or resistance). The important factors that control GMR are shown to be the spin-dependent random potential at interfaces and band matching/mismatching between magnetic and nonmagnetic layers. For TMR, several factors are shown to be important in determining the MR ratio, including the shape of the Fermi surface of the electrodes, the symmetry of the wave functions, electron scattering at interfaces, and spin-slip tunneling. An interpretation of TMR in Fe/MgO/Fe and of an oscillation of TMR is presented. TMR in granular films and in the Coulomb-blockade regime is also described. We also provide a brief explanation for other MR effects, such as normal MR, anisotropic MR (AMR) and colossal MR (CMR) in order to clarify the essential difference between these MRs and GMR, TMR, and BMR. These MR effects are attributed to the spin-dependent electrical currents produced in metallic ferromagnets. After the discovery of these different MR effects, the role of spin current was proposed, for example, spin Hall effect and the effects of spin transfer torque, which will be briefly explained in this chapter. The former orginates from the spin–orbit interaction, and can be observed even in nonmagnetic metals and semiconductors. It is closely related to the anomalous Hall effect observed in ferromagnetic metals. The spin transfer torque is an inverse effect of the MR. The MR is the resistivity change produced by magnetization rotation in ferromagnetic junctions, while the spin transfer torque is an effect in which spin-polarized current makes the magnetization rotate. Finally, we briefly introduce the coupled effects of spin, charge, and heat transport, which are called spin caloritronics.
III–V compound semiconductors such as GaAs and InAs alloyed with Mn exhibit ferromagnetism. The magnetic, electrical, and optical properties of ferromagnetic III–V semiconductors are first compiled along with the way to prepare the epitaxial films and the effect of postgrowth annealing. Theories available to explain the magnetism in these alloys are then presented. Because the ferromagnetic semiconductors are compatible with epitaxial III–V heterostructures, a number of device structures have been examined and shown to reveal a wide variety of phenomena that either cannot be realized or are very difficult to observe in ferromagnetic metal structures. The unique properties revealed by ferromagnetic semiconductor structures, ranging from reversible electric field control of ferromagnetic phase transition to generating velocity versus current-density curves of current-induced domain wall motion, are then reviewed. The prospect of realizing high-transition temperature is discussed in the last section.
This unique handbook compiles and details cutting-edge research in nanomagnetism and its applications in spintronics, magnetoplasmonics, and nonlinear magneto-optics. Fundamental aspects of magnetism relevant to nanodevices and new spin-transfer torque random-access memory (STT-RAM), current-induced domain wall motion memory, and spin torque oscillators, as well as highly anisotropic materials and topics on magnetization damping are developed in detail in the book. New paradigms such as molecule-based magnets (MBMs), which are a promisingly adaptive class of solids poised to open new frontiers of exploration, are also covered. The relationship between magnetism and nonlinear optics and the new field of magnetoplasmonics is also developed in detail. The book also includes a thorough chapter on spin-polarized scanning tunneling microscopy (SP-STM), which enables studying magnetic phenomena on surfaces with real-space imaging and spectroscopy techniques down to the atomic level. All these topics are developed by an interdisciplinary team of leading experts in their pertinent fields. The book will certainly appeal to anyone involved in nanomagnetism and its application in spintronic nanodevices and nonlinear magneto-optics.
Dynamical behavior of magnetic domain wall (DW) is one of the main issues in the field of spintronics. In this chapter, several experimental studies in DW dynamics in nanomagnetic systems are described. For the study of DW motion in nanoscale wires, samples with a trilayer structure, ferromagnetic/nonmagnetic/ferromagnetic, were prepared and the position of DW was estimated from electrical resistance measurements using giant magnetoresistance principle. The velocity of DW driven by an external field has been evaluated from the resistance change. On the other hand, current-driven DW motion in a single wire of ferromagnetic layer was studied by magnetic force microscopy (MFM). All-electrical control and local detection of multiple magnetic DWs are also shown. Magnetic vortex structures are realized in nanoscale ferromagnetic dot systems. The behavior of vortex core magnetization was observed by MFM. Recent topics such as the switching of vortex core driven by a high frequency AC are introduced. Furthermore, all-electrical operation of a magnetic vortex core memory cell is demonstrated.
The second edition of this book on nanomagnetism presents the basics and latest studies of low-dimensional magnetic nano-objects. It highlights the intriguing properties of nanomagnetic objects, such as thin films, nanoparticles, nanowires, nanotubes, nanodisks and nanorings as well as novel phenomena like spin currents. It also describes how nanomagnetism was an important factor in the rapid evolution of high-density magnetic recording and is developing into a decisive element of spintronics. Further, it presents a number of biomedical applications. With exercises and solutions, it serves as a graduate textbook.
Nanoscience is of central importance in the physical and biological sciences and is now pervasive in technology. However nanomagnetism has a special role to play as magnetic properties depend uniquely on both dimensionality and lengthscales. Nanomagnetism is already central to data storage, sensor and device technologies but is increasingly being used in the life sciences and medicine. This volume aims to introduce scientists, computer scientists, engineers and technologists from diverse fields to this fascinating and technologically important new branch of nanoscience. The volume should appeal to both the interested general reader but also to the researcher wishing to obtain an overview of this fast moving field. The contributions come from acknowledged leaders in the field who each give authoritative accounts of key fundamental aspects of nanomagnetism to which they have themselves made a major contribution. After a brief introduction by the editors, Wu first surveys the fundamental properties of magnetic nanostructures. The interlayer exchange interactions within magnetic multilayer structures is next discussed by Stiles. Camley then discusses the static, dynamic and thermal properties of magnetic multilayers and nanostructures, followed by an account of the phenomenon of exchange anisotropy by Berkowitz and Kodama. This latter phenomenon is widely in current read head devices for example. The transport properties of nanostructures also are spectacular, and again underpin computer technology, as we see from the discussion of giant magnetoresistance (GMR) and tunnelling magnetoresistance (TMR) presented by Fert and his colleagues. Beyond GMR and TMR we look to the field of spintronics where new electronic devices are envisioned and for which quantum computing may depend as discussed in the chapter by Flatte and Jonker. The volume concludes with discussion of the recently discovered phenomenon of current induced switching of magnetization by Edwards and Mathon. * Subject is in the forefront of nanoscience * All Section authors are leading figures in this key field * Presentations are accessible to non specialists, with focus on underlying fundamentals
The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism which already has a profound impact in technology and is providing the basis for a revolution in electronics. The last decade has seen dramatic progress in the development of magnetic devices for information technology but also in the basic understanding of the physics of magnetic nanostructures. Volume III describes thin film magnetic properties and methods for characterising thin film structure topics that underpin the present 'spintronics' revolution in which devices are based on combined magnetic materials and semiconductors. The present volume (IV) deals with the fundamentals of spintronics: magnetoelectronic materials, spin injection and detection, micromagnetics and the development of magnetic random access memory based on GMR and tunnel junction devices. Together these books provide readers with a comprehensive account of an exciting and rapidly developing field. The treatment is designed to be accessible both to newcomers and to experts already working in this field who would like to get a better understanding of this very diversified area of research.
Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.