{
  "abstract": "The bilayer iridate Sr$_3$Ir$_2$O$_7$ is a $c$-axis collinear antiferromagnet, held there by a giant interlayer pseudodipolar anisotropy, whereas single-layer Sr$_2$IrO$_4$ cants in the $ab$ plane. We show from first principles that biaxial compression of a few percent ($\\varepsilon_c\\approx-2.4\\%$) flops the easy axis of Sr$_3$Ir$_2$O$_7$ into the plane. A magnetic model Hamiltonian built from Wannier functions with no fitted parameter---reproducing the giant magnon gap of the bulk, so far known only from fits to experiment---identifies the mechanism. Compression collapses the interlayer exchange channel, whose straight Ir--O--Ir path weakens as the bent in-plane path strengthens. Hund's exchange sets the scale of the anisotropy and, beyond $J/U\\approx0.15$, removes the collinear state altogether. The flop is not a rigid rotation---the ordered moments of the two states cross at $\\varepsilon_c$---and it carries a stark fingerprint, in that the giant easy-axis magnon gap collapses to a gapless, Goldstone-like spectrum. Compressively strained films thus sit on a metamagnetic phase boundary ending in a zero-temperature bicritical point, a charge-neutral handle on spin--orbit-entangled order.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.22473",
  "author_total": 1,
  "authors": [
    {
      "name": "Choong H. Kim"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bfsphxc22mcrv.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.22473",
  "fulltext_url": null,
  "id": "bfsphxc22mcrv",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.22473",
  "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",
      "3104|Advanced Condensed Matter Physics"
    ]
  ],
  "openalex": "W7204159221",
  "pdf_url": "https://arxiv.org/pdf/2608.22473",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bfsphxc22mcrv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "2608.22473",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.22473"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Strain-driven spin-flop transition and collapse of the giant magnon gap in the bilayer iridate Sr$_3$Ir$_2$O$_7$",
  "title_text": "Strain-driven spin-flop transition and collapse of the giant magnon gap in the bilayer iridate Sr_3Ir_2O_7",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/bfsphxc22mcrv",
  "venue": "arXiv",
  "versions": []
}