Nonuniform switching ferromagnetic layers by spin polarized current

TL;DR

This paper investigates how spin-polarized currents induce nonuniform magnetic switching in ferromagnetic layers, leading to domain wall formation and oscillations, which are relevant for magnetic memory and spintronic devices.

Contribution

It introduces a model for nonuniform switching involving domain wall dynamics in ferromagnetic layers under spin-polarized current.

Findings

Nonuniform switching occurs with domain wall formation near the injector.

Domain walls can oscillate with a natural frequency influenced by external magnetic field.

Switching behavior depends on layer thickness and magnetic field strength.

Abstract

The magnetic reversal by spin-polarized current of a magnetic junction consisting of two ferromagnetic layers and a nonmagnetic spacer in between is considered. Initially, the free layer is magnetized antiparallel to the pinned layer by an external magnetic field. Under current flowing, a nonequilibrium spin polarization appears in the free layer. The interaction between the injected spins and the lattice leads to instability of the antiparallel orientation at the high enough current density and to switching the free layer to a state with magnetization parallel to one in the pinned layer. If the free layer thickness and the external magnetic field strength are large enough, then a nonuniform switching is favorable, so that only a part of the free layer near the injector switches. Such a switching is accompanied with appearance of a domain wall between the switched and non-switched regions. The domain wall can oscillate around the equilibrium position with some natural frequency depending on the external magnetic field.