{
  "abstract": "Ultrafast magnonics explores routes towards energy-efficient information processing by replacing electrons with pulses of terahertz magnons. The critical, but so far elusive, requirement on the magnon pulses is the combination of high-speed and a long-range propagation while maintaining a well-defined narrow waveform of the pulses. Here, we demonstrate the launching of 0.4-picosecond magnon pulses in the altermagnetic insulator $α$-Fe$_2$O$_3$ (hematite) using broadband terahertz spin-orbit torques by an adjacent platinum layer. Phase-resolved terahertz transmission reveals that these sub-picosecond pulses travel ballistically, coherently and non-dispersively at a constant velocity of 23 nm/ps, transport angular momentum and retain their temporal waveform shape over 160 nm, with an inferred relaxation length in hundreds of nanometers or more. Beyond establishing $α$-Fe$_2$O$_3$ as an optimal platform for ultrafast magnonics, our technique introduces a high-resolution, tabletop method to directly extract dispersion relations up to high wavevectors, and explore ultrafast magnon dynamics in altermagnets and other magnetic materials with teraherz-range dynamics.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.11550",
  "author_total": 23,
  "authors": [
    {
      "name": "Peter Kubaščík"
    },
    {
      "name": "Miina Leiviskä"
    },
    {
      "name": "Martin Bušina"
    },
    {
      "name": "Zdenek Kašpar"
    },
    {
      "name": "Katharina Müller"
    },
    {
      "name": "Jonathan Mak"
    },
    {
      "name": "Monika Scheufele"
    },
    {
      "name": "Gal Lemut"
    },
    {
      "name": "Jose Solano"
    },
    {
      "name": "Oliver Franke"
    },
    {
      "name": "Rostislav Matuška"
    },
    {
      "name": "Jiří Jechumtál"
    },
    {
      "name": "Eva Schmorranzerová"
    },
    {
      "name": "Petr Němec"
    },
    {
      "name": "Petr Kužel"
    },
    {
      "name": "Tobias Kampfrath"
    },
    {
      "name": "Piet W. Brouwer"
    },
    {
      "name": "Matthias Opel"
    },
    {
      "name": "Stephan Geprägs"
    },
    {
      "name": "Matthias Althammer"
    },
    {
      "name": "Tomáš Jungwirth"
    },
    {
      "name": "Helena Reichlova"
    },
    {
      "name": "Lukáš Nádvorník"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dd7nvwsbfc0t4.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.11550",
  "fulltext_url": null,
  "id": "dd7nvwsbfc0t4",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.11550",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "openalex",
      "3107|Magnetic properties of thin films"
    ]
  ],
  "openalex": "W7221100358",
  "pdf_url": "https://arxiv.org/pdf/2610.11550",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dd7nvwsbfc0t4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.11550",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.11550"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Demonstration of ultrafast coherent sub-picosecond magnon pulses",
  "title_text": "Demonstration of ultrafast coherent sub-picosecond magnon pulses",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/dd7nvwsbfc0t4",
  "venue": "arXiv",
  "versions": []
}