A strategy for the design of skyrmion racetrack memories

TL;DR

This paper explores the use of Neel skyrmions manipulated by the spin-Hall effect for racetrack memory, highlighting their advantages, limitations, and dynamics through micromagnetic simulations and analytical modeling.

Contribution

It introduces a comprehensive analysis of Neel skyrmion dynamics driven by spin-Hall effect for racetrack memory applications, including a new analytical model based on the Thiele equation.

Findings

Neel skyrmions driven by spin-Hall effect are promising for high-density, low-power racetrack memory.

High current excitation induces a breathing mode that limits skyrmion velocity.

Micromagnetic simulations confirm the potential and limitations of skyrmion-based memory devices.

Abstract

Magnetic storage based on racetrack memory is very promising for the design of ultra-dense, low-cost and low-power storage technology. Information can be coded in a magnetic region between two domain walls or, as predicted recently, in topological magnetic objects known as skyrmions. Here, we show the technological advantages and limitations of using Bloch and Neel skyrmions manipulated by spin current generated within the ferromagnet or via the spin-Hall effect arising from a non-magnetic heavy metal underlayer. We found that the Neel skyrmion moved by the spin-Hall effect is a very promising strategy for technological implementation of the next generation of skyrmion racetrack memories (zero field, high thermal stability, and ultra-dense storage). We employed micromagnetics reinforced with an analytical formulation of skyrmion dynamics that we developed from the Thiele equation. We identified that the excitation, at high currents, of a breathing mode of the skyrmion limits the maximal velocity of the memory.