{
  "abstract": "Altermagnetism is a recently established class of magnetic order that combines fully compensated moments with momentum-dependent spin splitting, yet identifying its spectroscopic fingerprints remains an open challenge. In this work, we investigate finite-momentum two-magnon excitations in a two-dimensional $d$-wave altermagnet by calculating the two-magnon light scattering intensity in different polarization channels. Using linear spin-wave theory and further incorporating the leading $1/S$ quantum corrections, we demonstrate that the characteristic magnon splitting of altermagnets shifts the upper edge of the two-magnon continuum and the corresponding spectral features to higher energy at $\\boldsymbol{X}=(π,0)$ relative to the conventional antiferromagnet, by an amount linear in the exchange anisotropy $|δJ_2|$, while leaving the response at the Brillouin-zone center unchanged. Although magnon-magnon interactions strongly redistribute spectral weight toward lower energies, the energy scale associated with the high-energy momentum-selective reconstruction remains robust. The interactions additionally generate a pronounced low-energy two-peak structure that has no counterpart within linear spin-wave theory. At $\\boldsymbol{K}=(π/2,π/2)$, we show that the interacting two-magnon resonance is twofold degenerate in the conventional antiferromagnetic phase, while a finite altermagnetic exchange anisotropy lifts this degeneracy, producing two peaks whose separation is linear in $|δJ_2|$. The characteristic energy scales underlying both features are intrinsic to the two-magnon sector rather than to a specific scattering operator. These findings highlight the potential of finite-momentum two-magnon spectroscopy for identifying altermagnetic order in insulating magnets and motivate momentum-resolved resonant inelastic x-ray scattering studies of candidate altermagnetic materials.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09287",
  "author_total": 3,
  "authors": [
    {
      "name": "Shuyi Li"
    },
    {
      "name": "Lexu Zhao"
    },
    {
      "name": "Chunjing Jia"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4syv2w09tkx5t.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09287",
  "fulltext_url": null,
  "id": "4syv2w09tkx5t",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09287",
  "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.str-el"
    ],
    [
      "openalex",
      "3104|Advanced Condensed Matter Physics"
    ]
  ],
  "openalex": "W7212195496",
  "pdf_url": "https://arxiv.org/pdf/2609.09287",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4syv2w09tkx5t.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.09287",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09287"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.str-el",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Two-magnon response from light scattering in altermagnets",
  "title_text": "Two-magnon response from light scattering in altermagnets",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/4syv2w09tkx5t",
  "venue": "arXiv",
  "versions": []
}