Reliable spin-transfer torque driven precessional magnetization reversal with an adiabatically decaying pulse

TL;DR

This paper demonstrates that a slowly decaying current pulse can reliably switch magnetization in nanomagnets despite noise, with the final state determined solely by pulse polarity, supported by numerical and analytical models.

Contribution

It introduces a method using adiabatically decaying pulses for nearly deterministic magnetization reversal in noisy environments, supported by new analytical insights.

Findings

Adiabatically decreasing pulses lead to reliable magnetization switching.

Thermal noise causes dephasing but does not prevent reversal with proper pulse decay.

Final magnetization state depends only on pulse polarity, not amplitude.

Abstract

We show that a slowly decaying current pulse can lead to nearly deterministic precessional switching in the presence of noise. We consider a biaxial macrospin, with an easy axis in the plane and a hard axis out-of-the plane, typical of thin film nanomagnets patterned into asymmetric shapes. Out-of-plane precessional magnetization orbits are excited with a current pulse with a component of spin polarization normal to the film plane. By numerically integrating the stochastic Landau-Lifshitz-Gilbert-Slonczewski equation we show that thermal noise leads to strong dephasing of the magnetization orbits. However, an adiabatically decreasing pulse amplitude overwhelmingly leads to magnetization reversal, with a final state that {\em only} depends on the pulse polarity, not on the pulse amplitude. We develop an analytic model to explain this phenomena and to determine the pulse decay time necessary for adiabatic magnetization relaxation and thus precessional magnetization switching.