Magnetization switching driven by spin-transfer-torque in high-TMR magnetic tunnel junctions

TL;DR

This study investigates magnetization switching in high-TMR magnetic tunnel junctions driven by spin-polarized currents, emphasizing the impact of nonuniform current density distribution and localized oscillation modes on switching behavior.

Contribution

It introduces a dynamic model of current density distribution in the free-layer and verifies the perpendicular current assumption through Poisson equation solutions.

Findings

Nonuniform current density causes switching asymmetry.

Localized pre-switching oscillation modes are identified.

Current distribution significantly influences switching dynamics.

Abstract

This paper describes a numerical experiment of magnetization switching driven by spin-polarized current in high-TMR magnetic tunnel junctions (TMR>100%). Differently from other works, the current density distribution throughout the cross-sectional area of the free-layer is here computed dinamically, by modeling the ferromagnet/insulator/ferromagnet trilayer as a series of parallel resistances. The validity of the main postulated hypothesis, which states that the current density vector is perpendicular to the sample plane, has been verified by numerically solving the Poisson equation. Our results show that the nonuniform current density distribution is a source of asymmetry for the switching. Furthermore, we found out that the switching processes are characterized by well defined localized pre-switching oscillation modes.