Spintronics: electron spin coherence, entanglement, and transport

The prospect of building spintronic devices in which electron spins store a nd transport information has attracted strong attention in recent years. He re we present some of our representative theoretical results on three funda mental aspects of spintronics: spin coherence, spin entanglement, and spin transport. In particular, we discuss our detailed quantitative theory for s pin relaxation and coherence in electronic materials, resolving in the proc ess a long-standing puzzle of why spin relaxation is extremely fast in Al ( compare with other simple metals). In the study of spin entanglement, we co nsider two electrons in a coupled GaAs double-quantum-dot structure and exp lore the Hilbert space of the double dot. The specific goal is to criticall y assess the quantitative aspects of the proposed spin-based quantum dot qu antum computer architecture. Finally we discuss our theory of spin-polarize d transport across a semiconductor/metal interface. In particular, we study Andreev reflection, which enables us to quantify the degree of carrier spi n polarization and the strength of interfacial scattering. (C) 2000 Academi c Press.