  In a nanomagnet (whose total spin S< 1000), very small polarized currents can
lead to magnetic reversal. Treating on the same footing the transport and
magnetic properties of a nanomagnet connected to magnetic leads via tunneling
barriers, we derive a closed equation for the time evolution of the
magnetization. The interplay between Coulomb blockade phenomena and magnetism
gives some additional structure to the current induced spin torque. In addition
to the possibility of stabilizing uniform spin waves, we find that the system
is highly hysteretic: up to three different magnetic states can be
simultaneously stable in one region of the parameter (magnetic field and bias
voltage) space.
