{
  "slug": "epmr",
  "term": "Energy-assisted perpendicular magnetic recording (ePMR)",
  "aliases": [
    "ePMR",
    "Energy-assisted PMR"
  ],
  "definition": "Energy-assisted perpendicular magnetic recording (ePMR) is Western Digital's write-assist approach in which a DC bias through the write pole makes the write field more consistent, reducing recording jitter.",
  "note": "Western Digital describes the bias as favoring a path for magnetization reversal in the write head [wd-recording-technologies]. This is distinct from MAS-MAMR's microwave-assisted reversal in the recording medium. ePMR is one approach within energy-assisted magnetic recording, not an alias for all EAMR or MAMR; it also does not specify CMR versus SMR track layout [wd-recording-technologies].",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    "The term identifies Western Digital's described write-assist mechanism, not a universal performance or capacity guarantee."
  ],
  "related": [
    "mamr",
    "fc-mamr",
    "mas-mamr",
    "pmr"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "wd-recording-technologies",
      "title": "Western Digital: Recording Technologies, pp. 3-5",
      "url": "https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/tech-brief/tech-brief-recording-technologies.pdf",
      "accessed": "2026-10-16"
    }
  ],
  "updated": "2026-10-16"
}