# US 10,121,496 B1 · Heat-assisted magnetic recording head having peg coupler and plasmonic pad > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,121,496 B1 - Document ID: US10121496B1 - Status: Granted - Kind: B1 - Application number: 15/901,991 - Filed: 2018-02-22 - Granted: 2018-11-06 - Earliest claimed: 2017-02-23 - Assignees: Seagate Technology LLC - Applicants: Seagate Technology LLC - Inventors: Chubing Peng; Tae-Woo Lee; Peng Zhang; Weibin Chen - Web page: https://patentgrep.com/patent/US10121496B1 ## CPC - G11B 5/314: {where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers (G11B5/3196 takes precedence)} - G11B 5/4866: {the arm comprising an optical waveguide, e.g. for thermally-assisted recording} - G11B 5/6088: {Optical waveguide in or on flying head} - G11B 7/1387: using the near-field effect - G11B 11/10534: {for recording by magnetising, demagnetising or transfer of magnetisation, by radiation, e.g. for thermomagnetic recording} - G11B 11/10536: {using thermic beams, e.g. lasers} - G11B 2005/0021: {Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A write head includes a waveguide, a magnetic pole, and a near-field transducer. The near-field transducer includes an enlarged portion and a peg. The peg is separated from the magnetic pole in a downtrack direction by a dielectric gap. A peg coupler covers a bottom surface of the magnetic pole and is separated from the peg. The peg coupler is formed of a first plasmonic material. A pad extends from the peg coupler into part of the gap in the downtrack direction towards the peg. The pad is formed of a second plasmonic material and extends into the write head away from the media-facing surface a distance L that is less than a corresponding distance of the peg coupler. ## Claims ### Claim 1 A write head comprising: a waveguide core; a magnetic pole; and a near-field transducer positioned at or near a media-facing surface and operatively coupled to the waveguide core, the near-field transducer comprising an enlarged portion and a peg extending from the enlarged portion towards the media-facing surface, the peg separated from the magnetic pole in a downtrack direction by a dielectric gap; a peg coupler covering a bottom surface of the magnetic pole near a tip of the magnetic pole and separated from the peg, the peg coupler formed of a first plasmonic material; and a pad that extends from the peg coupler into part of the gap in the downtrack direction towards the peg, the pad formed of a second plasmonic material and extending into the write head away from the media-facing surface a distance L that is less than a corresponding distance of the peg coupler. ### Claim 2 (depends on 1) The write head of claim 1, further comprising a heat sink extending from the enlarged portion of the near-field transducer to the magnetic pole, wherein the peg coupler, the pad, the heat sink, and the near-field transducer form an E-shaped cavity resonator that increases a thermal gradient of a hotspot created on a recording medium via the near-field transducer. ### Claim 3 (depends on 1) The write head of claim 1, wherein the pad has a crosstrack width that is the same as that of the peg coupler. ### Claim 4 (depends on 1) The write head of claim 1, wherein the pad has a crosstrack width that is the same as that of the peg. ### Claim 5 (depends on 1) The write head of claim 1, wherein the first and second plasmonic materials are selected from Ir, Rh, Pd, and Pt. ### Claim 6 (depends on 1) The write head of claim 1, wherein the first and second plasmonic materials are the same. ### Claim 7 (depends on 1) The write head of claim 1, wherein the near-field transducer heat sink is recessed from the media-facing surface by a distance TPH such that a magnitude of a downtrack electric field component on a down-track surface of the peg facing the peg coupler is greater than or equal to the downtrack electric field component on an opposing downtrack surface of the peg facing away from the peg coupler. ### Claim 8 (depends on 7) The write head of claim 7, wherein the peg extends a distance lPeg from the media-facing surface, TPH being greater than lPeg. ### Claim 9 (depends on 1) The write head of claim 1, wherein the waveguide core comprises a tapered end at the media-facing surface, the tapered end comprising a taper at an oblique angle to the media-facing surface, the taper facing away from the near-field transducer. ### Claim 10 (depends on 9) The write head of claim 9, wherein the tapered end reduces transverse mode coupling induced by the near-field transducer. ### Claim 11 (depends on 1) The write head of claim 1, wherein the pad comprises a sloped surface facing the near-field transducer, the sloped surface at an acute angle to the bottom surface of the magnetic pole. ### Claim 12 (depends on 11) The write head of claim 11, wherein the pad comprises a second surface joined to the sloped surface, the second surface proximate the media-facing surface and parallel to the bottom surface of the magnetic pole. ### Claim 13 (depends on 1) The write head of claim 1, wherein the pad comprises a major surface having a surface area greater than other surfaces of the pad that are not parallel to the major surface, the major surface parallel to the media-facing surface. ### Claim 14 (depends on 1) The write head of claim 1, wherein the pad comprises a major surface having a surface area greater than other surfaces of the pad that are not parallel to the major surface, the major surface parallel to the bottom surface of the magnetic pole. ### Claim 15 A write head comprising: a waveguide; a magnetic pole; and a near-field transducer positioned at or near a media-facing surface and operatively coupled to the waveguide, the near-field transducer comprising a peg extending away the media-facing surface a distance lPeg, the peg separated from the magnetic pole by a dielectric gap; a heat sink between the near-field transducer and the write pole, the heat sink recessed from the media-facing surface by a distance TPH that is equal to or greater than the distance lPeg; a peg coupler covering a bottom surface of the magnetic pole near a tip of the magnetic pole and separated from the peg in the downtrack direction, the peg coupler formed of a first plasmonic material; and a pad that extends from the peg coupler into part of the gap in the downtrack direction towards the peg, the pad formed of a second plasmonic material and extending away from the media-facing surface a distance L that is less than a corresponding distance of the peg coupler. ### Claim 16 (depends on 15) The write head of claim 15, wherein the peg coupler, the pad, the heat-sink, and the near-field transducer form an E-shaped cavity that increases a thermal gradient of a hotspot created on a recording medium via the near-field transducer. ### Claim 17 (depends on 15) The write head of claim 15, wherein the pad has an arc-shaped surface facing the near-field transducer. ### Claim 18 (depends on 15) The write head of claim 15, wherein the recession of the heat sink from the media-facing surface by the distance TPH results in a magnitude of a downtrack electric field component on a down-track surface of the peg facing the peg coupler being greater than or equal to the downtrack electric field component on an opposing downtrack surface of the peg facing away from the peg coupler. ### Claim 19 A method comprising: coupling light from a waveguide to a near-field transducer positioned at or near a media-facing surface, the near-field transducer comprising a peg extending towards the media-facing surface, the peg separated from a magnetic pole in a downtrack direction by a dielectric gap; forming a hotspot in a recording medium via the coupling of the light to the near-field transducer; and increasing a thermal gradient of the hotspot via a peg coupler and a pad that together form an E-shaped cavity of plasmonic material, the peg coupler covering a bottom surface of the magnetic pole near a tip of the magnetic pole and separated from the peg, the pad extending from the peg coupler into part of the gap in the downtrack direction towards the peg, the pad extending into the write head away from the media-facing surface a distance L that is less than a corresponding distance of the peg coupler. ### Claim 20 (depends on 19) The method of claim 19, wherein a heat sink is located between the near-field transducer and the magnetic pole, the heat sink comprising a recess from the media-facing surface by a distance TPH, the method comprising equalizing a magnitude of a downtrack electric field component on opposing downtrack surfaces of the peg via the recess of the heat sink.