  It is shown that a pulsed current driven through Ni nanowires provokes an
irreversible magnetization reversal at a field distant from the spontaneous
switching field $H_{sw}$ by $\Delta H$ of as much as 40 % of $H_{sw}$. The
state of the magnetization is assessed by magnetoresistive measurements carried
out on single, isolated nanowires. The reversible part of the magnetization
follows that of a uniform rotation. The switching occurs between the two states
accessible otherwise by normal field ramping. $\Delta H$ is studied as a
function of the angle between the applied field and the wire, and also of the
direction of the pulsed current. The results are interpreted in terms of
spin-flip transfer from the spin-polarized current to the magnetization, while
the switching is approximated by a curling reversal mode.
