{
  "abstract": "Controlling the charge and spin degrees of freedom of electrons in solids has been at the heart of condensed-matter science for centuries. One hallmark of metallic conduction is the Wiedemann-Franz law which implies that a moving charge carries entropy. Despite centuries of dedicated research, disentangling charge and heat transport has remained an unsolved issue so far. Here we present a direct route to reduce thermal conductivity of conduction electrons with respect to their electrical conductivity via energy-dependent scattering. By constraining electronic transport to a boxcar-type distribution asymmetrically around the Fermi energy, a large Seebeck coefficient and electrical conductivity can be realized simultaneously while electronic heat conduction is suppressed. Based on the case of monolayer Ni$_3$In, which comprises two flat bands around the Fermi energy, we propose flat-band systems as a promising, tunable platform for scattering phase space engineering. Besides this novel approach, our large-scale assessment of $\\approx 5\\times 10^4$ data sets in a 'Wiedemann-Franz plot' of $zT$ vs. $S^2$ provides an effective tool to identify reports of $L\\ll L_0$ from literature - pointing towards either new and interesting physical mechanisms - or overlooked measurement artifacts.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.16261",
  "author_total": 6,
  "authors": [
    {
      "name": "Illia Serhiienko"
    },
    {
      "name": "Fabian Garmroudi"
    },
    {
      "name": "Stefan Enzner"
    },
    {
      "name": "Izem Dural"
    },
    {
      "name": "Giorgio Sangiovanni"
    },
    {
      "name": "Andrej Pustogow"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8d2ty1jmh14mj.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.16261",
  "fulltext_url": null,
  "id": "8d2ty1jmh14mj",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.16261",
  "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.mtrl-sci"
    ],
    [
      "openalex",
      "2505|Advanced Thermoelectric Materials and Devices"
    ]
  ],
  "openalex": "W7213397584",
  "pdf_url": "https://arxiv.org/pdf/2609.16261",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8d2ty1jmh14mj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:41Z",
      "native_id": "2609.16261",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.16261"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Breaking the Wiedemann-Franz limit in thermoelectrics via separated flat bands",
  "title_text": "Breaking the Wiedemann-Franz limit in thermoelectrics via separated flat bands",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:41Z",
  "url": "https://research.draconitic.com/paper/8d2ty1jmh14mj",
  "venue": "arXiv",
  "versions": []
}