title: A strategy for the design of skyrmion racetrack memories.
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 Néel 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 Néel 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.
authors.affiliation: Department of Computer Science, Modelling, Electronics and System Science, University of Calabria, Via P. Bucci I-87036, Rende (CS), Italy.
authors.forename: R
authors.initials: R
authors.lastname: Tomasello
authors.affiliation: Department of Fisica Aplicada, Universidad de Salamanca, Plaza de los Caidos s/n, E-38008, Salamanca, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Martinez
authors.affiliation: Department of Physics and Earth Sciences and CNISM Unit of Ferrara, University of Ferrara, Ferrara, via Saragat 1, I-44122 Ferrara, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Zivieri
authors.affiliation: Department of Fisica Aplicada, Universidad de Salamanca, Plaza de los Caidos s/n, E-38008, Salamanca, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Torres
authors.affiliation: Department of Electrical and Information Engineering, Politecnico of Bari, via E. Orabona 4, I-70125 Bari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Carpentieri
authors.affiliation: Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166, Messina, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Finocchio