{
  "slug": "hamr",
  "term": "Heat-assisted magnetic recording (HAMR)",
  "aliases": [
    "energy-assisted recording"
  ],
  "definition": "An HDD technology that briefly heats the media with a laser so bits can be written on high-coercivity material at higher density.",
  "note": "HAMR addresses the writeability/thermal-stability trade-off at high areal density: media grains are made highly coercive so tiny bits stay stable at room temperature, then a laser diode on the write head briefly heats a nanoscale spot so the magnetic writer can flip polarity; the spot cools in about a nanosecond. Seagate’s shipping Mozaic platform pairs superlattice high-anisotropy media with a plasmonic (near-field) writer. HAMR changes how small bits are written, not whether tracks are shingled—Mozaic SKUs appear in vendor CMR/SMR matrices as CMR or SMR variants. It targets mass-capacity nearline density; seek and rotational latency remain mechanical. Public production emphasis has been Seagate; other vendors discuss HAMR on their own qualification timelines.",
  "status": "shipping",
  "advantages": [
    {
      "text": "Extends areal density beyond PMR alone by using thermally assisted writes.",
      "citationIds": [
        "c1",
        "c2"
      ]
    }
  ],
  "limitations": [],
  "related": [
    "mamr",
    "pmr",
    "nearline-hdd",
    "helium-hdd"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": {
    "date": "2024",
    "citationIds": [
      "c2"
    ]
  },
  "lastSeen": null,
  "citations": [
    {
      "id": "c1",
      "title": "Heat-assisted magnetic recording",
      "url": "https://en.wikipedia.org/wiki/Heat-assisted_magnetic_recording",
      "accessed": "2026-03-26"
    },
    {
      "id": "c2",
      "title": "Seagate begins shipping HAMR drives",
      "url": "https://www.seagate.com/news/news-archive/seagate-begins-shipping-hamr-drives/",
      "accessed": "2026-03-26"
    },
    {
      "id": "n3",
      "title": "Seagate — Heat-Assisted Magnetic Recording (HAMR)",
      "url": "https://www.seagate.com/innovation/hamr/",
      "accessed": "2026-10-07"
    },
    {
      "id": "n4",
      "title": "Seagate — What is Mozaic 3+ (plasmonic write path)",
      "url": "https://www.seagate.com/resources/what-is-mozaic-3plus-how-does-it-work-and-what-can-it-do-for-my-data-center/",
      "accessed": "2026-10-07"
    },
    {
      "id": "n5",
      "title": "Seagate — Gen 2 plasmonic writer",
      "url": "https://www.seagate.com/innovation/mozaic/gen-2-plasmonic-writer/",
      "accessed": "2026-10-07"
    }
  ]
}