# US 2014/0153128 A1 · Magnetic recording medium, method of manufacturing the same, and magnetic recording/reproduction apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153128 A1 - Document ID: US20140153128A1 - Status: Published application - Kind: A1 - Application number: 13/793,409 - Filed: 2013-03-11 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Kabushiki Kaisha Toshiba - Applicants: Kabushiki Kaisha Toshiba - Inventors: Hironori TEGURI; Akira WATANABE; Tomoko TAGUCHI - Web page: https://patentgrep.com/patent/US20140153128A1 ## CPC - G11B 5/7375: {for heat-assisted or thermally-assisted magnetic recording [HAMR, TAMR]} - G11B 5/657: {containing inorganic, non-oxide compound of Si, N, P, B, H or C, e.g. in metal alloy or compound (containing oxygen G11B5/658)} - G11B 5/658: {containing oxygen, e.g. molecular oxygen or magnetic oxide} - G11B 5/7369: {Two or more non-magnetic underlayers, e.g. seed layers or barrier layers} - G11B 5/851: Coating a support with a magnetic layer by sputtering - 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 According to one embodiment, a magnetic recording medium includes a magnetic recording layer formed on a substrate and including magnetic grains and a grain boundary formed between the magnetic grains, the grain boundary includes a first grain boundary having a first thermal conductivity, and a second grain boundary formed on the first grain boundary and having a second thermal conductivity different from the first thermal conductivity, and at least one of the first and second grain boundaries suppresses thermal conduction. ## Claims ### Claim 1 A magnetic recording medium comprising: a substrate; and a magnetic recording layer formed on the substrate, and comprising magnetic grains and a grain boundary formed between the magnetic grains, wherein the grain boundary comprises a first grain boundary having a first thermal conductivity, and a second grain boundary formed on the first grain boundary and having a second thermal conductivity different from the first thermal conductivity, and at least one of the first grain boundary and the second grain boundary is configured to suppress thermal conduction. ### Claim 2 (depends on 1) The medium of claim 1, further comprising a heat-sink layer between the substrate and the magnetic recording layer. ### Claim 3 (depends on 2) The medium of claim 2, wherein the heat-sink layer contains at least one material selected from the group consisting of silver, copper, gold, and alloys thereof. ### Claim 4 (depends on 2) The medium of claim 2, further comprising a thermal barrier layer between the heat-sink layer and the magnetic recording layer. ### Claim 5 (depends on 4) The medium of claim 4, wherein the thermal barrier layer contains ZrO2. ### Claim 6 (depends on 1) The medium of claim 1, wherein the magnetic grains are selected from the group consisting of an iron-platinum alloy having an L10 structure, a cobalt-platinum alloy having the L10 structure, and a multilayered film of cobalt and platinum. ### Claim 7 (depends on 1) The medium of claim 1, wherein each of the first grain boundary and the second grain boundary is selected from a layer made of at least one material selected from the group consisting of carbon, SiO2, and TiO2, and an air gap defined by the layer and the magnetic grains. ### Claim 8 A magnetic recording medium manufacturing method comprising: forming, on a substrate, a magnetic recording layer including magnetic grains and a grain boundary formed between the magnetic grains and made of a first material; and forming a trench by removing at least a portion of the grain boundary, and forming, on the trench, a layer made of a second material having a thermal conductivity lower than that of the first material, thereby forming a structure in which the grain boundary is divided into a first grain boundary having a first thermal conductivity and a second grain boundary formed on the first grain boundary and having a second thermal conductivity different from the first thermal conductivity, and at least one of the first grain boundary and the second grain boundary suppresses thermal conduction. ### Claim 9 (depends on 8) The method of claim 8, further comprising forming a heat-sink layer on the substrate before the forming the magnetic recording layer. ### Claim 10 (depends on 9) The method of claim 9, wherein the heat-sink layer contains at least one material selected from the group consisting of silver, copper, gold, and alloys thereof. ### Claim 11 (depends on 9) The method of claim 9, further comprising forming a thermal barrier layer on the heat-sink layer before the forming the magnetic recording layer. ### Claim 12 (depends on 11) The method of claim 11, wherein the thermal barrier layer contains ZrO2. ### Claim 13 (depends on 8) The method of claim 8, wherein the manufacturing the magnetic recording medium comprises sputtering an FePt—C target or Co, Pt, and C targets. ### Claim 14 (depends on 8) The method of claim 8, wherein each of the first grain boundary and the second grain boundary is selected from a layer made of at least one material selected from the group consisting of carbon, SiO2, and TiO2, and an air gap defined by the layer and the magnetic grains. ### Claim 15 (depends on 14) The method of claim 14, wherein the first material is carbon, and the second material is one of SiO2 and TiO2. ### Claim 16 A magnetic recording/reproduction apparatus comprising: a magnetic recording medium comprising a substrate, and a magnetic recording layer formed on the substrate, and including magnetic grains and a grain boundary formed between the magnetic grains, the grain boundary including a first grain boundary having a first thermal conductivity, and a second grain boundary formed on the first grain boundary and having a second thermal conductivity different from the first thermal conductivity, and at least one of the first grain boundary and the second grain boundary suppressing thermal conduction; and a magnetic head including a heat source configured to heat the magnetic recording medium. ### Claim 17 (depends on 16) The apparatus of claim 16, further comprising a heat-sink layer between the substrate and the magnetic recording layer. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the heat-sink layer contains at least one material selected from the group consisting of silver, copper, gold, and alloys thereof. ### Claim 19 (depends on 16) The apparatus of claim 16, wherein the magnetic grains are selected from the group consisting of an iron-platinum alloy having an L10 structure, a cobalt-platinum alloy having the L10 structure, and a multilayered film of cobalt and platinum. ### Claim 20 (depends on 16) The apparatus of claim 16, wherein each of the first grain boundary and the second grain boundary is selected from a layer made of at least one material selected from the group consisting of carbon, SiO2, and TiO2, and an air gap defined by the layer and the magnetic grains.