  Prospect of building electronic devices in which electron spins store and
transport information has revived interest in the spin relaxation of conduction
electrons. Since spin-polarized currents cannot flow indefinitely, basic
spin-electronic devices must be smaller than the distance electrons diffuse
without losing its spin memory. Some recent experimental and theoretical effort
has been devoted to the issue of modulating the spin relaxation. It has been
shown, for example, that in certain materials doping, alloying, or changing
dimensionality can reduce or enhance the spin relaxation by several orders of
magnitude. This brief review presents these efforts in the perspective of the
current understanding of the spin relaxation of conduction electrons in
nonmagnetic semiconductors and metals.
