Overview of spin transport electronics in metals

Spintronics has emerged as an exciting and dynamic field of research and development that spans numerous disciplines, including condensed matter physics, materials science, optical science and electrical engineering. The field can be divided roughly into two approaches. The first seeks to utilize the unique properties of ferromagnetic materials for novel functionality in electronic devices by incorporating a magnetic element in a device structure. This approach relies on spin-dependent transport of conduction electrons for integrating a magnetic bit state with charge-based electronic technology. Applications include magnetic field sensors incorporated as read heads and integrated, nonvolatile magnetic random-access memories. The second theme is less conventional and seeks to utilize populations of spin-polarized electrons, or individual magnetic moments, for entirely new paradigms of information processing such as quantum computing. Research in these two areas finds common ground with the study of the optical and/or electronic spin transport properties of conduction electrons. This paper will focus on relatively near term applications, represented by the first, more conventional theme, and on basic principles of spin-polarized transport.