{
  "abstract": "Twisted bilayer graphene (TBG) near the first magic angle ($θ\\approx1.05^{\\circ}$) hosts flat bands that provide a fertile ground for exploring strongly correlated and topological phases. At smaller twist angles ($θ<1^{\\circ}$), attice relaxation profoundly alters the moiré landscape. The extent to which moiré lattice reconstruction at different length scales affects the electronic structure through electro-mechanical coupling remains unresolved. Here, using scanning tunneling microscopy on small-angle TBG devices ($θ\\approx0.3-0.7^{\\circ}$), we observe a pronounced $dI/dV$ peak at the AA site of the moiré lattice on top of a spectrum that is asymmetric about the charge neutrality point, lattice reconstruction over moiré lattice length scales, as well as a dilation of the atomic lattice at the AA sites. We demonstrate at a phenomenological level that the inclusion of moiré lattice reconstruction supports compact localized heavy fermion $f-$ states localized at AA sites. The additional inclusion of atomic lattice dilation enerates a strong flexo-electric response that explicitly breaks particle-hole symmetry, pushing compact, localized $f$-states at the AA sites down in energy. Consequently, these heavy fermion states energetically coexist with itinerant $c$-electrons at the AB/BA sites. Our spatially resolved spectroscopic measurements quantitatively visualize this coexistence, confirming the persistence of the heavy fermion model in the small-angle regime $θ<1^{\\circ}$. Our findings provide microscopic insights into how flexo-electricity affects the low-energy electronic structure of small-angle TBG. More broadly, our study establishes small-angle TBG as a new class of moiré materials to explore the interacting Kondo lattice problem with high tunability of the $f-$occupation and $c-$density through twist-angle and electrostatic back gates, respectively.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.38305",
  "author_total": 6,
  "authors": [
    {
      "name": "Qirong Yao"
    },
    {
      "name": "Ka Cheuk Fan"
    },
    {
      "name": "Tianyu Qiao"
    },
    {
      "name": "Hao Shi"
    },
    {
      "name": "Xi Dai"
    },
    {
      "name": "Berthold Jäck"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9v80jcd16v7g7.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.38305",
  "fulltext_url": null,
  "id": "9v80jcd16v7g7",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.38305",
  "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.mes-hall"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.38305",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9v80jcd16v7g7.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:23Z",
      "native_id": "2610.38305",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.38305"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mes-hall",
      "subfield": "condensed-matter"
    }
  ],
  "title": "The Flexoelectric Twist: Persistence of Heavy Fermion Picture in Small-Angle Twisted Bilayer Graphene",
  "title_text": "The Flexoelectric Twist: Persistence of Heavy Fermion Picture in Small-Angle Twisted Bilayer Graphene",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:17Z",
  "url": "https://research.draconitic.com/paper/9v80jcd16v7g7",
  "venue": "arXiv",
  "versions": []
}