{
  "id": "2506.16818",
  "version": "v1",
  "published": "2025-06-20T08:16:25.000Z",
  "updated": "2025-06-20T08:16:25.000Z",
  "title": "Effective Field Theory of a Noncollinear Altermagnet",
  "authors": [
    "Seungho Lee",
    "Se Kwon Kim"
  ],
  "comment": "17 pages, 4 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We derive an effective field theory for a noncollinear altermagnet and magnons on top of the noncollinear ground state from an altermagnetic Heisenberg model. We obtain the ground-state phase diagram, revealing a noncollinear phase and four distinct collinear phases. The ground state of the noncollinear phase fully breaks the spin rotational symmetry, while the ground state of the collinear phases possesses unbroken $\\mathrm{SO}(2)$ symmetry. The resulting effective field theory for the noncollinear phase is an $\\mathrm{SO}(3)$ sigma model in which the magnonic excitation has three independent degrees of freedom and exhibits the $d$-wave-like anisotropic linear dispersion. We also discuss possible topological solitons, including $\\mathbb{Z}_2$ vortices.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-06-20T08:16:25.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "effective field theory",
      "noncollinear altermagnet",
      "collinear phases possesses unbroken",
      "altermagnetic heisenberg model",
      "anisotropic linear dispersion"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}