Theory Of Point Contact Spectroscopy In Normal Metals

Various experimental techniques for point contact production are described. Examples of point-contact spectra are presented for pure metals, alloys and compounds, as well as for semimetals and semiconductors, heavy fermion systems, Kond-lattices, mixed valence compounds and more. Superconducting point contacts are considered in respect to Andreev reflection and Josephson effects. Special attention is paid to contact conductance fluctuation, and new trends of research are outlined.

The characteristics of electrical contacts have long attracted the attention of researchers since these contacts are used in every electrical and electronic device. Earlier studies generally considered electrical contacts of large dimensions, having regions of current concentration with diameters substantially larger than the characteristic dimensions of the material: the interatomic distance, the mean free path for electrons, the coherence length in the superconducting state, etc. [110]. The development of microelectronics presented to scientists and engineers the task of studying the characteristics of electrical contacts with ultra-small dimensions. Characteristics of point contacts such as mechanical stability under continuous current loads, the magnitudes of electrical fluctuations, inherent sensitivity in radio devices and nonlinear characteristics in connection with electromagnetic radiation can not be understood and altered in the required way without knowledge of the physical processes occurring in contacts. Until recently it was thought that the electrical conductivity of contacts with direct conductance (without tunneling or semiconducting barriers) obeyed Ohm's law. Nonlinearities of the current-voltage characteristics were explained by joule heating of the metal in the region of the contact. However, studies of the current-voltage characteristics of metallic point contacts at low (liquid helium) temperatures [142] showed that heating effects were negligible in many cases and the nonlinear characteristics under these conditions were observed to take the form of the energy dependent probability of inelastic electron scattering, induced by various mechanisms.

The great breakthroughs in the science and technology of superconducting and magnetic materials in recent years promoted many outstanding representatives of various scientific disciplines (physics, chemistry and materials science) to present their latest findings in a scientific atmosphere of the highest standard at the MSM-99 conference. Over 200 eminent scientists from 50 countries gathered to discuss the physics, materials science and application of magnetic and superconducting materials, and to foster research and development collaborations between the scientists and technologists of the regional countries and also with the international scientific community.The main topics of this book are the physics, materials science and application of magnetic and superconducting materials having a close relationship between the strong correlated electron system and magnetism.

The great breakthroughs in the science and technology of superconducting and magnetic materials in recent years promoted many outstanding representatives of various scientific disciplines (physics, chemistry and materials science) to present their latest findings in a scientific atmosphere of the highest standard at the MSM-99 conference. Over 200 eminent scientists from 50 countries gathered to discuss the physics, materials science and application of magnetic and superconducting materials, and to foster research and development collaborations between the scientists and technologists of the regional countries and also with the international scientific community. The main topics of this book are the physics, materials science and application of magnetic and superconducting materials having a close relationship between the strong correlated electron system and magnetism.

The continuous evolution and development of experimental techniques is at the basis of any fundamental achievement in modern physics. Strongly correlated systems (SCS), more than any other, need to be investigated through the greatest variety of experimental techniques in order to unveil and crosscheck the numerous and puzzling anomalous behaviors characterizing them. The study of SCS fostered the improvement of many old experimental techniques, but also the advent of many new ones just invented in order to analyze the complex behaviors of these systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. The volume presents a representative collection of the modern experimental techniques specifically tailored for the analysis of strongly correlated systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for any other researcher in the field who appreciates consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possible way, with the working details of a specific technique.

Quantum mechanical laws are well documented at the level of a single or a few atoms and are here extended to systems containing 102 to 1010 electrons - still much smaller than the usual macroscopic objects, but behaving in a manner similar to a single atom. Besides the purely theoretical interest, such systems pose a challenge to the achievement of the ultimate microelectronic applications. The present volume presents an up-to-date account of the physics, technology and expected applications of quantum effects in solid-state mesoscopic structures. Physical phenomena include the Aharonov-Bohm effect, persistent currents, Coulomb blockade and Coulomb oscillations in single electron devices, Andreev reflections and the Josephson effect in superconductor/normal/superconductor systems, shot noise suppression in microcontacts and contact resistance quantisation, and overall quantum coherence in mesoscopic and nanoscopic structures related to the emerging physics of quantum computation in the solid-state environment.

Spintronics Handbook, Second Edition offers an update on the single most comprehensive survey of the two intertwined fields of spintronics and magnetism, covering the diverse array of materials and structures, including silicon, organic semiconductors, carbon nanotubes, graphene, and engineered nanostructures. It focuses on seminal pioneering work, together with the latest in cutting-edge advances, notably extended discussion of two-dimensional materials beyond graphene, topological insulators, skyrmions, and molecular spintronics. The main sections cover physical phenomena, spin-dependent tunneling, control of spin and magnetism in semiconductors, and spin-based applications. Features: Presents the most comprehensive reference text for the overlapping fields of spintronics (spin transport) and magnetism. Covers the full spectrum of materials and structures, from silicon and organic semiconductors to carbon nanotubes, graphene, and engineered nanostructures. Extends coverage of two-dimensional materials beyond graphene, including molybdenum disulfide and study of their spin relaxation mechanisms Includes new dedicated chapters on cutting-edge topics such as spin-orbit torques, topological insulators, half metals, complex oxide materials and skyrmions. Discusses important emerging areas of spintronics with superconductors, spin-wave spintronics, benchmarking of spintronics devices, and theory and experimental approaches to molecular spintronics. Evgeny Tsymbal's research is focused on computational materials science aiming at the understanding of fundamental properties of advanced ferromagnetic and ferroelectric nanostructures and materials relevant to nanoelectronics and spintronics. He is a George Holmes University Distinguished Professor at the Department of Physics and Astronomy of the University of Nebraska-Lincoln (UNL), Director of the UNL’s Materials Research Science and Engineering Center (MRSEC), and Director of the multi-institutional Center for NanoFerroic Devices (CNFD). Igor Žutić received his Ph.D. in theoretical physics at the University of Minnesota. His work spans a range of topics from high-temperature superconductors and ferromagnetism that can get stronger as the temperature is increased, to prediction of various spin-based devices. He is a recipient of 2006 National Science Foundation CAREER Award, 2005 National Research Council/American Society for Engineering Education Postdoctoral Research Award, and the National Research Council Fellowship (2003-2005). His research is supported by the National Science Foundation, the Office of Naval Research, the Department of Energy, and the Airforce Office of Scientific Research.