{
  "abstract": "Precise knowledge of the total number of magnons, including both coherent and incoherent (e.g. thermal) excitations, is imperative for the advancement of fundamental spin-wave physics and the development of next-generation magnonic devices. In particular, quantifying magnons is key to understanding magnon transport phenomena, the nonlinear regime, or ultrafast magnetization dynamics. Typically, incoherent magnons are accessed by frequency-domain techniques, which lack the temporal resolution required for ultrafast processes, while ultrafast time-domain methods are generally sensitive only to the coherent dynamics. In this work, we demonstrate that femtosecond noise correlation spectroscopy enables a fully quantitative, time-domain measurement of both thermal and coherently excited magnon modes in bismuth-substituted yttrium iron garnet driven by a free-running microwave. We model the experimental data and extract the magnon number by simulating the magnon band structure of the sample, the magneto-optical response function, and the optical spot size used in the experiment. Our analysis establishes a connection between magnon mode calculations and experimentally accessible magnetic properties and fiducially reproduces the waveform and amplitude of the magneto-optical correlation signal for different experimental conditions. These results open a new pathway towards the optical tomography of magnon modes in non-linear or non-equilibrium conditions and can be readily extended to study ultrafast incoherent dynamics in other condensed matter systems.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.07421",
  "author_total": 8,
  "authors": [
    {
      "name": "F. S. Herbst"
    },
    {
      "name": "M. A. Weiss"
    },
    {
      "name": "A. Leitenstorfer"
    },
    {
      "name": "M. Lammel"
    },
    {
      "name": "N. Beaulieu"
    },
    {
      "name": "J. Ben Youssef"
    },
    {
      "name": "R. Schlitz"
    },
    {
      "name": "S. T. B. Goennenwein"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/av76f2mh2p442.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.07421",
  "fulltext_url": null,
  "id": "av76f2mh2p442",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.07421",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "3107|Magnetic properties of thin films"
    ]
  ],
  "openalex": "W7212019905",
  "pdf_url": "https://arxiv.org/pdf/2609.07421",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/av76f2mh2p442.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.07421",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.07421"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "Quantifying thermal and driven magnon populations with femtosecond noise correlation spectroscopy",
  "title_text": "Quantifying thermal and driven magnon populations with femtosecond noise correlation spectroscopy",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/av76f2mh2p442",
  "venue": "arXiv",
  "versions": []
}