Stationary magnetization states in a thin magnetic layer of a nanopillar multilayer structure subjected to a spin-polarized current and a magnetic field

Abstract

The static and dynamic equilibrium states of spins in a thin layer of a conducting nanosized column containing two magnetic layers are analyzed theoretically. The magnetization of one of the layers is assumed to be fixed. The analysis is performed in terms of a macrospin model with allowance for the Slonczewski-Berger torque transfer. Bifurcation diagrams are constructed describing the change of spin states in the current-field plane. The relation of the specific features of varying magnetization and the spin precession frequency to bifurcations in the dynamic system under study is discussed. It is shown that the soft creation of cycles with a zero amplitude is accompanied by precession at a finite frequency and that the precession frequency becomes zero when a cycle with a finite amplitude disappears or arises in a jump. Comparative analysis is performed for two orientations of a magnetic field (parallel and perpendicular to the easy magnetization axis in the layer plane) in the presence of a current with a given spin orientation.