  The miniaturisation of magnetic read heads and random access memory elements
makes them vulnerable to thermal fluctuations. We demonstrate how
current-induced spin-transfer torques can be used to suppress the effects of
thermal fluctuations. This enhances the fidelity of perpendicular magnetic spin
valves. The simplest realization is a dc current to stabilize the free magnetic
layers. The power can be significantly reduced without losing fidelity by
simple control schemes, in which the stabilizing current-induced spin-transfer
torque is controlled by the instantaneous resistance.
