  Magnetization behavior of long nanowires with square cross-section under
influence of strong perpendicular spin-polarized current is studied
theoretically. The study is based on Landau-Lifshitz-Slonczewski phenomenology.
In the no current case the wire is magnetized uniformly along its axis. For
small currents the wire magnetization remains uniform but it inclines with
respect to the wire axis within the plane perpendicular to the current
direction. With the current increasing the inclination angle increases up to
the maximum value $\pi/4$. Further current increase leads either to saturation
or to stable periodic multidomain structure depending on the wire thickness.
For thick wires a hysteresis is observed in the saturation process under the
action of current. All critical parameters of the current induced magnetization
behavior are determined theoretically. The study is carried out both
analytically and using micromagnetic simulations.
