{
  "status": "unknown",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-17",
  "slug": "magnetic-recording-trilemma",
  "term": "Magnetic recording trilemma",
  "aliases": [
    "recording trilemma"
  ],
  "definition": "The magnetic recording trilemma is the coupled constraint of signal-to-noise ratio, thermal stability and writability as recording density increases.",
  "note": "Maintaining enough grains per recorded bit for signal quality while shrinking the bit calls for smaller grains. At fixed material properties and temperature, smaller grain volume lowers the thermal reversal barrier. Increasing anisotropy restores stability but demands a stronger write field [evans-2012].\n\nHAMR separates hot writing from cooler storage, easing this conflict. It does not remove the need to bias the intended magnetic state strongly enough against thermal fluctuations during writing; that additional requirement is thermal writability [evans-2012].",
  "related": [
    "hamr",
    "pmr",
    "magnetic-anisotropy",
    "superparamagnetic-limit",
    "thermal-writability"
  ],
  "citations": [
    {
      "id": "evans-2012",
      "title": "Evans et al.: Thermally induced error: density limit for magnetic data storage (2012), doi:10.1063/1.3691196",
      "url": "https://arxiv.org/html/1111.0524v2",
      "accessed": "2026-10-17"
    }
  ],
  "provenance": [
    "Evans et al. discuss the trilemma before deriving an idealized aligned-axis equilibrium model. Their numerical density forecasts are not universal commercial-HDD limits."
  ]
}