Sadamichi Maekawa – författare

Since the discovery of the giant magnetoresistance (GMR) effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. Recent progress in the physics of magnetism and the application of spin current has progressed in tandem with the nanofabricationtechnology of magnets and the engineering of interfaces and thin films. This book is intended to provide an introduction and guide to the new physics and applications of spin current. The emphasis is placed on the interaction between spin and charge currents in magnetic nanostructures.

Nowadays information technology is based on semiconductor and ferromagnetic materials. Information processing and computation are based on electron charge in semiconductor transistors and integrated circuits, and information is stored on magnetic high-density hard disks based on the physics of the electron spins. Recently, a new branch of physics and nanotechnology, called magneto-electronics, spintronics, or spin electronics, has emerged, which aims at simultaneously exploiting both the charge and the spin of electrons in the same device. A broader goal is to develop new functionality that does not exist separately in a ferromagnet or a semiconductor. The aim of this book is to present new directions in the development of spin electronics in both the basic physics and the technology which will become the foundation of future electronics.

Since the discovery of the giant magnetoresistance (GMR) effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. Recent progress in the physics of magnetism and the application of spin current has progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book is intended to provide an introduction and guide to the new physics and applications of spin current. The emphasis is placed on the interaction between spin and charge currents in magnetic nanostructures.

In magnetic systems of nano-meter size, the interplay between spin and charge of electrons provides unique transport phenomena. In magnetic superlattices, magnetic and non-magnetic metallic thin films with thickness of the order of one nano-meter are piled-up alternately. Since the discovery of giant magnetoresistance (GMR) in these superlattices in 1988, spin dependent transport phenomena in magnetic nanostructures have received much attention from both academic and technological points of view.Ferromagnetic tunnel junctions made of ferromagnetic metal electrodes and a very thin insulating barrier between them are also of current interest as magnetoresistive devices, where the tunneling current depends on the relative orientation of magnetization (TMR). In addition to magnetic superlattices and magnetic tunnel junctions, magnetic granular systems and magnetic dots have been studied extensively as magnetoresistive systems.Edited by two of the world's leading authorities, Spin Dependent Transport in Magnetic Nanostructures introduces and explains the basic physics and applications of a variety of spin-dependent transport phenomena in magnetic nanostructures with particular emphasis on magnetic multilayers and magnetic tunnel junctions.

In magnetic systems of nano-meter size, the interplay between spin and charge of electrons provides unique transport phenomena. In magnetic superlattices, magnetic and non-magnetic metallic thin films with thickness of the order of one nano-meter are piled-up alternately. Since the discovery of giant magnetoresistance (GMR) in these superlattices in 1988, spin dependent transport phenomena in magnetic nanostructures have received much attention from both academic and technological points of view.Ferromagnetic tunnel junctions made of ferromagnetic metal electrodes and a very thin insulating barrier between them are also of current interest as magnetoresistive devices, where the tunneling current depends on the relative orientation of magnetization (TMR). In addition to magnetic superlattices and magnetic tunnel junctions, magnetic granular systems and magnetic dots have been studied extensively as magnetoresistive systems.Edited by two of the world's leading authorities, Spin Dependent Transport in Magnetic Nanostructures introduces and explains the basic physics and applications of a variety of spin-dependent transport phenomena in magnetic nanostructures with particular emphasis on magnetic multilayers and magnetic tunnel junctions.

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.

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.

This volume contains the proceedings of the ffiM Japan International Sympo­ sium on Strong Correlation and Superconductivity, which was held in Keidan­ ren Guest House at the foot of Mt. Fuji, May 21-25, 1989. The purpose of the Symposium was to provide an opportunity for discus­ sions on the problem of strong correlation of electrons in the context of high-Tc superconductivity. Sixty-eight scientists were invited from seven countries and forty-three papers were presented in the Symposium. Soon after the discovery ofhigh-Tc superconducting oxides, Professor P. W. Anderson proposed that the essence of high-Tc superconductivity lies in the strong correlation among the electrons in these materials. This proposal has stimulated a wide range of theoretical investigations on this profound and dif­ ficult problem, which are expected to lead eventually to new concepts describ­ ing strong electron correlation. In the Symposium, Anderson himself started lively discussions by his talk entitled "Myth and Reality in High-Tc Supercon­ ductivity", which was followed by various reports on theoretical studies and experimental results. Concise and thoughtful summaries of experiment and theory were given by Professors H. R. Ott and P. A. Lee, respectively. It is our hope that this volume reflects the present status of the research activity on this outstanding problem from the viewpoint of the basic physics and that it will further stimulate the effort to understand these fascinating systems, the high-Tc oxides.

This volume contains the proceedings of the ffiM Japan International Sympo­ sium on Strong Correlation and Superconductivity, which was held in Keidan­ ren Guest House at the foot of Mt. Fuji, May 21-25, 1989. The purpose of the Symposium was to provide an opportunity for discus­ sions on the problem of strong correlation of electrons in the context of high-Tc superconductivity. Sixty-eight scientists were invited from seven countries and forty-three papers were presented in the Symposium. Soon after the discovery ofhigh-Tc superconducting oxides, Professor P. W. Anderson proposed that the essence of high-Tc superconductivity lies in the strong correlation among the electrons in these materials. This proposal has stimulated a wide range of theoretical investigations on this profound and dif­ ficult problem, which are expected to lead eventually to new concepts describ­ ing strong electron correlation. In the Symposium, Anderson himself started lively discussions by his talk entitled "Myth and Reality in High-Tc Supercon­ ductivity", which was followed by various reports on theoretical studies and experimental results. Concise and thoughtful summaries of experiment and theory were given by Professors H. R. Ott and P. A. Lee, respectively. It is our hope that this volume reflects the present status of the research activity on this outstanding problem from the viewpoint of the basic physics and that it will further stimulate the effort to understand these fascinating systems, the high-Tc oxides.

Advances through carefully conducted quantitative work onwell designed, high quality materials characterize thepresent state of high-temperature superconductivityresearch. The contributions to this volume present atheoretical and experimental overview of electronicstructure and physical properties, including anisotropicfeatures, of high-temperative materials, with a focus oncuprates.In order to enhance the understanding of the mechanisms ofsuperconductivity at high temperatures, this volume isdivided into theoretical and experimental parts. Thecontributions to the two parts correspond to each other,giving readers involved in either area of research activitya reference to findingsof the other.On the other hand, this book gives young physicistshigh-level information on the present state of research,enhanced by tutorial contributions of leading physicists inthe field.

Advances through carefully conducted quantitative work onwell designed, high quality materials characterize thepresent state of high-temperature superconductivityresearch. The contributions to this volume present atheoretical and experimental overview of electronicstructure and physical properties, including anisotropicfeatures, of high-temperative materials, with a focus oncuprates.In order to enhance the understanding of the mechanisms ofsuperconductivity at high temperatures, this volume isdivided into theoretical and experimental parts. Thecontributions to the two parts correspond to each other,giving readers involved in either area of research activitya reference to findingsof the other.On the other hand, this book gives young physicistshigh-level information on the present state of research,enhanced by tutorial contributions of leading physicists inthe field.