Subnanosecond magnetization reversal of magnetic nanoparticle driven by chirp microwave field pulse

TL;DR

This paper demonstrates that a linear down-chirp microwave pulse can induce subnanosecond magnetization reversal in magnetic nanoparticles more efficiently than constant-frequency fields, especially with added spin-polarized current.

Contribution

It introduces the use of down-chirp microwave pulses for rapid, low-energy magnetization reversal, a novel approach compared to traditional methods.

Findings

Down-chirp pulses enable subnanosecond reversal.

Reduced field amplitude needed with chirp and spin current.

Fast reversal achieved by energy exchange during crossing.

Abstract

We investigate the magnetization reversal of single-domain magnetic nanoparticle driven by linear down-chirp microwave magnetic field pulse. Numerical simulations based on the Landau-Lifshitz-Gilbert equation reveal that solely down-chirp pulse is capable of inducing subnanosecond magnetization reversal. With a certain range of initial frequency and chirp rate, the required field amplitude is much smaller than that of constant-frequency microwave field. The fast reversal is because the down-chirp microwave field acts as an energy source and sink for the magnetic particle before and after crossing over the energy barrier, respectively. Applying a spin-polarized current additively to the system further reduces the microwave field amplitude. Our findings provide a new way to realize low-cost and fast magnetization reversal.