Generation and routing of nanoscale droplet solitons without compensation of magnetic damping

TL;DR

This paper demonstrates theoretically that nanoscale droplet solitons can be generated and routed in ferromagnetic nanostructures using voltage-controlled magnetic anisotropy without needing to compensate magnetic damping, enabling potential spintronic applications.

Contribution

It introduces a novel method to generate and route droplet solitons via voltage-controlled anisotropy without damping compensation, supported by micromagnetic simulations.

Findings

Droplet solitons form under voltage pulses in MgO/Fe/MgO trilayers.

Solitons can live up to 50 ns at room temperature.

Electrical routing of solitons is achievable with nanostripe electrodes.

Abstract

Magnetic droplet soliton is a localized dynamic spin state which can serve as a nanoscale information carrier and nonlinear oscillator. The present opinion is that the formation of droplet solitons requires the compensation of magnetic damping by a torque created by a spin-polarized electric current or pure spin current. Here we demonstrate theoretically that nanoscale droplet solitons can be generated and routed in ferromagnetic nanostructures with voltage-controlled magnetic anisotropy in the presence of uncompensated magnetic damping. Performing micromagnetic simulations for the MgO/Fe/MgO trilayer with almost perpendicular-to-plane magnetization, we reveal the formation of the droplet soliton under a nanoscale gate electrode subjected to a sub-nanosecond voltage pulse. The soliton lives up to 50 ns at room temperature and can propagate over micrometer distances in a ferromagnetic waveguide due to nonzero gradient of the demagnetizing field. Furthermore, we show that an electrical routing of the soliton to different outputs of a spintronic device can be realized with the aid of an additional semiconducting nanostripe electrode creating controllable gradient of the perpendicular magnetic anisotropy.