{
  "abstract": "We investigate the field-dependent low-energy thermodynamics of the distorted triangular quantum antiferromagnet $\\mathrm{Cu}_3(\\mathrm{OH})_4(\\mathrm{HCO}_2)_2$ using a sector-resolved Superblock Diagonalization Method (SBDM) supplemented by a transfer-matrix treatment of weakly coupled layers. The strong exchange hierarchy, dominated by the Cu1--Cu1 intradimer coupling $J_2=150\\,\\mathrm{K}$, separates a high-energy dimer sector from a much softer magnetic manifold formed predominantly by the Cu2 moments. In the 24-site cluster, sixteen Cu1 spins form the strongly bound sector while eight Cu2 spins remain magnetically active; polarization of these eight spins gives $S^z=4$ compared with $S^z_{\\rm sat}=12$, providing a direct microscopic origin for the one-third magnetization scale. The finite-temperature thermodynamics reveals a non-monotonic field evolution of the low-energy scale: the dominant $C/T$ feature softens with increasing field, reaches a minimum near the field region around $2\\,\\mathrm{T}$, and subsequently hardens as the low-temperature magnetization approaches $M_{\\rm sat}/3$. Temperature and field sweeps thus expose a common field-induced spectral reconstruction, while the strongly reduced entropy reflects the restricted number of thermally active degrees of freedom below the dimer excitation scale. Our results identify strong-dimer-induced reduction of the active magnetic Hilbert space, followed by field-driven reorganization of the residual spin sector, as the common microscopic origin of the one-third magnetic response and the non-monotonic low-temperature thermodynamics.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.39966",
  "author_total": 2,
  "authors": [
    {
      "name": "Sk Saniur Rahaman"
    },
    {
      "name": "S. R. Hassan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2gaxn8ad7wtwd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.39966",
  "fulltext_url": null,
  "id": "2gaxn8ad7wtwd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.39966",
  "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": "W7215108779",
  "pdf_url": "https://arxiv.org/pdf/2609.39966",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2gaxn8ad7wtwd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:03Z",
      "native_id": "2609.39966",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.39966"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.str-el",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Strong Dimerization and Field-Induced Reconstruction of the Low-Energy Spectrum in $\\mathrm{Cu}_3(\\mathrm{OH})_4(\\mathrm{HCO}_2)_2$",
  "title_text": "Strong Dimerization and Field-Induced Reconstruction of the Low-Energy Spectrum in Cu_3(OH)_4(HCO_2)_2",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:03Z",
  "url": "https://research.draconitic.com/paper/2gaxn8ad7wtwd",
  "venue": "arXiv",
  "versions": []
}