{
  "abstract": "We present magnetic-field-dependent evolution of magnetization and spin dynamics in the quasi-two-dimensional spin-$1/2$ magnet $\\mathrm{Cu_2(OH)_3Br}$, consisting of alternately coupled ferromagnetic Cu1 and antiferromagnetic Cu2 spin chains. Terahertz spectroscopy reveals a pronounced field-direction dependence of the low-energy magnetic excitation spectrum. For magnetic fields applied perpendicular to the spin chains, $B\\parallel a$ and $B\\parallel c^*$, the spectra undergo abrupt reconstructions at the spin-flop transitions identified independently by high-field magnetization measurements. For $B\\parallel b$, by contrast, no spin-flop occurs; instead, the excitation spectrum evolves continuously with field and exhibits a strong terahertz radiation polarization dependence as the ferromagnetic Cu1 subsystem becomes progressively polarized. At higher fields, the complex low-field spectrum is replaced by a reduced set of broad excitations, consistent with a weakening of the coupling between the ferromagnetic and antiferromagnetic chain subsystems. Complementary Raman spectroscopy resolves magnon and spinon excitations alongside several phonon modes and traces the characteristic temperature- and magnetic-field-dependent evolution of the magnetic excitations. The combined spectroscopic and magnetization results map out how a magnetic field reorganizes the coupled ferromagnetic and antiferromagnetic subsystems in $\\mathrm{Cu_2(OH)_3Br}$ across field-induced phase transitions.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.06246",
  "author_total": 16,
  "authors": [
    {
      "name": "Anneke Reinold"
    },
    {
      "name": "Dirk Wulferding"
    },
    {
      "name": "Laur Peedu"
    },
    {
      "name": "Kirill Amelin"
    },
    {
      "name": "Urmas Nagel"
    },
    {
      "name": "Toomas Rõõm"
    },
    {
      "name": "Zhiying Zhao"
    },
    {
      "name": "Patrick Pilch"
    },
    {
      "name": "Changqing Zhu"
    },
    {
      "name": "Hans Engelkamp"
    },
    {
      "name": "Lucas Berger"
    },
    {
      "name": "Denis I. Gorbunov"
    },
    {
      "name": "Yurii Skourski"
    },
    {
      "name": "Kwang-Yong Choi"
    },
    {
      "name": "Thomas Lorenz"
    },
    {
      "name": "Zhe Wang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/80krcewtq4vfq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.06246",
  "fulltext_url": null,
  "id": "80krcewtq4vfq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.06246",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "3104|Advanced Condensed Matter Physics"
    ]
  ],
  "openalex": "W7212065572",
  "pdf_url": "https://arxiv.org/pdf/2609.06246",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/80krcewtq4vfq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.06246",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.06246"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.str-el",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Magnetization processes and spin dynamics across field-induced phase transitions in the quasi-two-dimensional quantum magnet Cu$_2$(OH)$_3$Br",
  "title_text": "Magnetization processes and spin dynamics across field-induced phase transitions in the quasi-two-dimensional quantum magnet Cu_2(OH)_3Br",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/80krcewtq4vfq",
  "venue": "arXiv",
  "versions": []
}