Magnetization reversal triggered by spin injection in magnetic nanowires

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.