Periodic magnetization structures generated by transverse spin current in magnetic nanowires

The magnetization behavior of long nanowires with square cross section under the influence of strong perpendicular spin-polarized current is studied theoretically. The study is based on Landau-Lifshitz-Slonczewski phenomenology. Without the current 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 increasing current the inclination angle increases up to the maximum value π/4. Further current increase leads either to saturation or to a stable periodic multidomain structure depending on the wire thickness. For thick wires a hysteresis is observed in the saturation process under the action of the current. All critical parameters of the current induced magnetization behavior are determined theoretically. The study is carried out both analytically and numerically using micromagnetic simulations.