{
  "abstract": "Direct characterization of the spin centers that provide the magnetic states of low-dimensional magnetic materials is key to understand whether the magnetic properties arise from defects, interfaces, or surface-specific coordination environments, and how they can thus be employed in devices. The spectroscopic technique par excellence for this purpose is electron paramagnetic resonance (EPR) which has seen recent expansion to single spins but remains challenging for nanostructures on insulating surfaces. Here, we overcome this limitation and demonstrate local spin-resonance spectroscopy of nanoscale systems on insulators. We achieve this by combining EPR detection with scanning microwave microscopy (SMM) at X-band frequencies of ≈9.3 GHz, with resonant spin absorptions identified as local field-dependent microwave losses, available by mapping the complex admittance under a swept magnetic field. We demonstrate the potential of the technique on single flakes of the two-dimensional Fe–Ni Hofmann clathrate. The new technique reveals a thickness-dependent evolution from bulk-like toward low-dimensional spinresonance behavior, allowing the investigation of flakes from ≈5-15 nm to >100–200 nm thick, in conditions inaccessible to other surface EPR methods. The observed thickness-dependent response is consistent with increasing contributions from surface, interface, and undercoordinated Fe environments. These new developments allow a unique route to probe dimensional effects in magnetism, make surface effects and defects accessible in insulators, and open the possibility of directly observing EPR not just on atoms and molecules, but on single electronic nanodevices, such as Single Electron Transistors and quantum dots.",
  "abstract_shown": true,
  "affiliations": [
    "Johannes Kepler University Linz, Gruberstraße 40, Linz, 4020",
    "Instituto de Ciencia Molecular, Universitat de València, Catedrático José Beltrán 2, Paterna, Spain, 46980",
    "Università degli Studi di Firenze, Via della Lastruccia, 3, Sesto Fiorentino, Italy, 50019",
    "School of Chemistry",
    "University of Birmingham",
    "Diamond Light Source, Electron Physical Science Imaging Centre, OX11 0DE, Didcot, UK"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Gianluca Fabi"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Ramon Torres",
      "orcid": "0000-0002-3431-6113"
    },
    {
      "affs": [
        0
      ],
      "name": "Maxwell Sparey"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Javier Castells-Gil"
    },
    {
      "affs": [
        5
      ],
      "name": "Christopher S. Allen"
    },
    {
      "affs": [
        1
      ],
      "name": "Joaquin Soriano-Lopez"
    },
    {
      "affs": [
        2
      ],
      "name": "Lapo Bogani"
    },
    {
      "affs": [
        0
      ],
      "name": "Georg Gramse"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/86f2h5wjffbc4.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15010070/v1",
  "fulltext_url": null,
  "id": "86f2h5wjffbc4",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010070/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1304|Electron Spin Resonance Studies"
    ]
  ],
  "openalex": "W7221008466",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15010070/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-07",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/86f2h5wjffbc4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "10.26434/chemrxiv.15010070",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010070/v1"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "openalex:1304|Electron Spin Resonance Studies",
      "subfield": "biophysics"
    }
  ],
  "title": "Electron Paramagnetic Resonance on a Tip Reveals Thickness-Dependent Spin Heterogeneity in Two-",
  "title_text": "Electron Paramagnetic Resonance on a Tip Reveals Thickness-Dependent Spin Heterogeneity in Two-",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/86f2h5wjffbc4",
  "venue": "ChemRxiv",
  "versions": []
}