{
  "id": "1508.04821",
  "version": "v1",
  "published": "2015-08-19T22:44:56.000Z",
  "updated": "2015-08-19T22:44:56.000Z",
  "title": "Skyrmion dynamics in chiral ferromagnets under spin-transfer torque",
  "authors": [
    "Stavros Komineas",
    "Nikos Papanicolaou"
  ],
  "comment": "7 pages, 5 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We study the dynamics of skyrmions under spin-transfer torque in Dzyaloshinskii-Moriya materials with easy-axis anisotropy. In particular, we study the motion of a topological skyrmion with skyrmion number $Q=1$ and a non-topological skyrmionium with $Q=0$ using their linear momentum, virial relations, and numerical simulations. The non-topological $Q=0$ skyrmionium is accelerated in the direction of the current flow and it either reaches a steady state with constant velocity, or it is elongated to infinity. The steady-state velocity is given by a balance between current and dissipation and has an upper limit. In contrast, the topological $Q=1$ skyrmion converges to a steady-state with constant velocity at an angle to the current flow. When the spin current stops the $Q=1$ skyrmion is spontaneously pinned whereas the $Q=0$ skyrmionium continues propagation. Exact solutions for the propagating skyrmionium are identified as solutions of equations given numerically in a previous work. Further exact results for propagating skyrmions are given in the case of the pure exchange model. The traveling solutions provide arguments that a spin-polarized current will cause rigid motion of a skyrmion or a skyrmionium.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-08-19T22:44:56.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spin-transfer torque",
      "chiral ferromagnets",
      "skyrmion dynamics",
      "current flow",
      "constant velocity"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}