Investigation of spin wave - skyrmion interactions for magnonic information processing

Abstract

Magnonic computing (MC) architectures based on spin waves are increasingly of interest for special-purpose computing applications [1]. MC offers advantages over conventional charge-based computing [2-5], including low power dissipation (magnon propagation does not require charge transfer), and incorporation of phase information in addition to amplitude, reducing the component count needed for certain logic operations [6]. One of the challenges in the realization of most MC concepts is that they require an efficient means for routing magnons in complex networks. In particular, a scalable, nonvolatile, and reconfigurable mechanism to do so is currently lacking [6,7]. Here we address this challenge by utilizing a Néel skyrmion as a programmable scattering center to route magnons. The skyrmion is stabilized by the interfacial Dzyaloshinskii-Moriya Interaction (DMI) and perpendicular magnetic anisotropy (PMA), which itself can be controlled by electric fields via the voltage-controlled magnetic anisotropy (VCMA) effect, making the magnon-skyrmion interaction tunable by voltage. We investigate the interaction of exchange spin waves with wavelength of 26 to 190 nm, with skyrmions having diameters from 9 to 74 nm. Our micromagnetic simulations show that the propagation, scattering angle, and energy transmission of spin waves can be effectively controlled by tuning the ratio of magnon wavelength to the skyrmion diameter, which depends strongly on PMA and DMI. Based on this approach, we propose a new skyrmionic magnon switch (SMS) device, which provides voltage-controlled routing of spin waves in a magnetic wire and can be applied to build basic logic circuits. We simulate the SMS performance using typical material parameters for thin ferromagnetic films supporting skyrmions, and assess the requirements for its experimental realization.