{
  "abstract": "The square--octagon lattice provides a useful setting for studying magnetic adatoms because its multisublattice structure allows different adsorption geometries to probe distinct combinations of the host electronic states. We study magnetic adatoms in an $s$-wave superconducting square--octagon lattice, focusing on the interplay between adsorption geometry, narrow and flat-band states, and subgap transport. We find that the large spectral weight associated with a flat band does not necessarily imply strong impurity--host coupling. For symmetric square-hollow adsorption, destructive interference strongly suppresses the overlap with the flat-band manifold, whereas top and octagon-hollow adsorption retain substantial overlap. This selectivity is reflected in the magnetic bound states, with the square-hollow channel supporting a predominantly atomic state, while the top and octagon-hollow states are strongly hybridized with the superconducting host. The effect develops continuously as the relevant band becomes flatter and remains pronounced in a material-motivated parameter regime. In a normal--superconductor--normal geometry, these differences are also reflected in the nonlocal subgap conductance. At a representative exchange splitting, square-hollow adsorption suppresses the low-bias conductance relative to the clean device, whereas octagon-hollow adsorption enhances it, with the square-hollow response showing a much sharper dependence on exchange splitting. Our results show that the magnetic-adatom response in narrow and flat-band superconductors is governed by the available spectral weight and by the symmetry and wave-function structure of the impurity--host hybridization.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.07546",
  "author_total": 1,
  "authors": [
    {
      "name": "Ravi Kiran"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/44w9qk1zpkw1y.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.07546",
  "fulltext_url": null,
  "id": "44w9qk1zpkw1y",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.07546",
  "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.supr-con"
    ],
    [
      "openalex",
      "3104|Physics of Superconductivity and Magnetism"
    ]
  ],
  "openalex": "W7212046435",
  "pdf_url": "https://arxiv.org/pdf/2609.07546",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/44w9qk1zpkw1y.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.07546",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.07546"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.supr-con",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Interference-controlled magnetic bound states and subgap transport in a Square--octagon superconductor",
  "title_text": "Interference-controlled magnetic bound states and subgap transport in a Square--octagon superconductor",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/44w9qk1zpkw1y",
  "venue": "arXiv",
  "versions": []
}