{
  "abstract": "The discovery of high-temperature ferromagnetism in the metallic van der Waals (vdW) system Fe$_N$GeTe$_2$ has brought two-dimensional (2D) magnets into technologically relevant temperature scales. Specifically at N = 5, dilution of magnetic moments by nickel substitution counterintuitively achieves a record high Curie temperature of 478~K. Unraveling the origin of this nickel-substitution-induced enhancement is complicated by the compound's structural complexity, coexistent itinerant and local magnetic contributions, and mesoscopic compositional domains. Through coordinated structural and electronic characterization, we identify that the high-T$_C$ magnetic phase arises from a strain-stabilized Fe$_6$GeTe$_2$ nano-precipitate. Combining first-principles calculations and spin- and angle-resolved photoemission spectroscopy (ARPES), we uncover a site-specific electronic landscape in which interior iron atoms primarily host localized moments while the outer iron atoms neighboring the tellurium layers produce spin-polarized itinerant carriers that cross the vdW gap. The large energy cost associated with homogeneous nickel substitution is found to favor the spontaneous precipitation of the crystallographically and electronically ``clean'' high-T$_C$ phase. Finally, we compare metal-rich vdW magnets with binary magnetic alloys, and discuss the unifying roles of nano-precipitates in stabilizing otherwise unattainable bulk phases. Our work provides mechanistic insights into the record-high T$_C$ ferromagnetism in (Fe,Ni)$_{5+δ}$GeTe$_2$, establishing a rigorous foundation for the atomic engineering of vdW magnetic metals informed by direct electronic signatures.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.11862",
  "author_total": 26,
  "authors": [
    {
      "name": "Tyler L. Werner"
    },
    {
      "name": "Jonathan T. Reichanadter"
    },
    {
      "name": "Xiang Chen"
    },
    {
      "name": "Pranab K. Nag"
    },
    {
      "name": "Luna Y. Liu"
    },
    {
      "name": "Yu-Tsun Shao"
    },
    {
      "name": "Hongrui Zhang"
    },
    {
      "name": "Mingyang Guo"
    },
    {
      "name": "Wenxin Li"
    },
    {
      "name": "Zhibo Kang"
    },
    {
      "name": "Han Wu"
    },
    {
      "name": "Makoto Hashimoto"
    },
    {
      "name": "Donghui Lu"
    },
    {
      "name": "Turgut Yilmaz"
    },
    {
      "name": "Elio Vescovo"
    },
    {
      "name": "Sung-Kwan Mo"
    },
    {
      "name": "Barat Achinuq"
    },
    {
      "name": "Alexei Fedorov"
    },
    {
      "name": "Jacob C. Ruff"
    },
    {
      "name": "Ming Yi"
    },
    {
      "name": "Qiong Ma"
    },
    {
      "name": "David A. Muller"
    },
    {
      "name": "Eduardo H. da Silva Neto"
    },
    {
      "name": "Robert J. Birgeneau"
    },
    {
      "name": "Jeffrey B. Neaton"
    },
    {
      "name": "Yu He"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3sxnd8g3hm45y.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.11862",
  "fulltext_url": null,
  "id": "3sxnd8g3hm45y",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.11862",
  "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"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "2505|2D Materials and Applications"
    ]
  ],
  "openalex": "W7212222308",
  "pdf_url": "https://arxiv.org/pdf/2609.11862",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3sxnd8g3hm45y.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:26Z",
      "native_id": "2609.11862",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.11862"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "High-Temperature ferromagnetism from site-selective filling in (Fe,Ni)$_{6-δ}$GeTe$_2$",
  "title_text": "High-Temperature ferromagnetism from site-selective filling in (Fe,Ni)_6−δGeTe_2",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:26Z",
  "url": "https://research.draconitic.com/paper/3sxnd8g3hm45y",
  "venue": "arXiv",
  "versions": []
}