title: Skyrmion-Based Dynamic Magnonic Crystal.
abstract: A linear array of periodically spaced and individually controllable skyrmions is introduced as a magnonic crystal. It is numerically demonstrated that skyrmion nucleation and annihilation can be accurately controlled by a nanosecond spin polarized current pulse through a nanocontact. Arranged in a periodic array, such nanocontacts allow the creation of a skyrmion lattice that causes a periodic modulation of the waveguide's magnetization, which can be dynamically controlled by changing either the strength of an applied external magnetic field or the density of the injected spin current through the nanocontacts. The skyrmion diameter is highly dependent on both the applied field and the injected current. This implies tunability of the lowest band gap as the skyrmion diameter directly affects the strength of the pinning potential. The calculated magnonic spectra thus exhibit tunable allowed frequency bands and forbidden frequency bandgaps analogous to that of conventional magnonic crystals where, in contrast, the periodicity is structurally induced and static. In the dynamic magnetic crystal studied here, it is possible to dynamically turn on and off the artificial periodic structure, which allows switching between full rejection and full transmission of spin waves in the waveguide. These findings should stimulate further research activities on multiple functionalities offered by magnonic crystals based on periodic skyrmion lattices.
authors.affiliation: †Temasek Laboratories, National University of Singapore, 119077 Singapore.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Ma
authors.affiliation: ‡Department of Physics, University of Hong Kong, Hong Kong, P. R. China.|⊥York-Nanjing Joint Center for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: §School of Physics, University College Dublin, Dublin 4, Ireland.
authors.forename: H B
authors.initials: HB
authors.lastname: Braun
authors.affiliation: ∥School of Physical and Mathematical Sciences, Nanyang Technological University, 639798 Singapore.
authors.forename: W S
authors.initials: WS
authors.lastname: Lew
mesh_terms: D060526:Magnetic Fields; D053758:Nanoparticles
keywords: magnetic skyrmions; magnonics; spin torque; spin waves; spintronics