{
  "id": "2505.07083",
  "version": "v1",
  "published": "2025-05-11T18:14:17.000Z",
  "updated": "2025-05-11T18:14:17.000Z",
  "title": "Fermi liquid theory of $d$-wave altermagnets: demon modes and Fano-demon states",
  "authors": [
    "Habib Rostami",
    "Johannes Hofmann"
  ],
  "comment": "6 pages, 3 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We develop a Fermi liquid theory of $d$-wave altermagnets and apply it to describe their collective excitation spectrum. We predict that in addition to a conventional undamped plasmon mode, where both spin components oscillate in phase, there is an acoustic plasmon (or {\\em demon}) mode with out-of-phase spin dynamics. By analyzing the dynamical structure factor, we reveal a strong dependence of the demon's frequency and spectral weight both on the Landau parameters and on the direction of propagation. Notably, as a function of the propagation angle, we show that the acoustic mode evolves from a {\\em hidden state}, which has zero spectral weight in the density excitation spectrum, to a weakly damped propagating demon mode and then to a {\\em Fano-demon mixed state}, which is marked by a strong hybridization with particle-hole excitations and a corresponding asymmetric line shape in the structure factor. Our study paves the way for applications of altermagnetic materials in opto-spintronics by harnessing itinerant electron spin oscillations beyond traditional magnon spin waves.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-05-11T18:14:17.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "fermi liquid theory",
      "wave altermagnets",
      "fano-demon states",
      "itinerant electron spin oscillations",
      "damped propagating demon mode"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}