Spin–orbit coupling and spin transport

Recent achievements in semiconductor spintronics are discussed. Special attention is paid to spin–orbit interaction, coupling of electron spins to external electric fields, and spin transport in media with spin–orbit coupling, including the mechanisms of spin-Hall effect. Importance of spin-transport parameters at spin-precession wave vector k_so is emphasized, and existence of an universal relation between spin currents and spin accumulation at the spatial scale of is conjectured.