Quasistatic and Pulsed Current-Induced Switching with Spin-Orbit Torques in Ultrathin Films with Perpendicular Magnetic Anisotropy

TL;DR

This study compares quasistatic and pulsed current-induced switching in ultrathin magnetic films with perpendicular anisotropy, revealing that short pulses cause partial reversal due to limited domain expansion time.

Contribution

It provides new insights into the switching dynamics of ultrathin magnetic films under pulsed currents, highlighting the limitations of rapid switching for applications.

Findings

Complete reversal occurs at a threshold current in quasistatic conditions.

Short, high-amplitude pulses lead to partial reversal and domain formation.

Limited domain expansion time causes incomplete switching during fast pulses.

Abstract

Spin-orbit interaction derived spin torques provide a means of reversing the magnetization of perpendicularly magnetized ultrathin films with currents that flow in the plane of the layers. A basic and critical question for applications is the speed and efficiency of switching with nanosecond current pulses. Here we investigate and contrast the quasistatic (slowly swept current) and pulsed current-induced switching characteristics of micron scale Hall crosses consisting of very thin ($<1$ nm) perpendicularly magnetized CoFeB layers on $\beta$-Ta. While complete magnetization reversal is found at a threshold current density in the quasistatic case, short duration ($\leq 10$ ns) larger amplitude pulses ($\simeq 10 \times$ the quasistatic threshold current) lead to only partial magnetization reversal and domain formation. We associate the partial reversal with the limited time for reversed domain expansion during the pulse.