# US 8,771,849 B2 · Perpendicular magnetic recording medium and magnetic recording/reproducing apparatus using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,849 B2 - Document ID: US8771849B2 - Status: Granted - Kind: B2 - Application number: 12/288,654 - Filed: 2008-10-21 - Published: 2009-08-06 - Granted: 2014-07-08 - Earliest claimed: 2007-11-02 - Assignees: HGST Netherlands B.V. - Applicants: Hiroaki Nemoto; Ikuko Takekuma; Ichiro Tamai; Yoshiyuki Hirayama - Inventors: Hiroaki Nemoto; Ikuko Takekuma; Ichiro Tamai; Yoshiyuki Hirayama - Web page: https://patentgrep.com/patent/US8771849B2 ## CPC - G11B 5/672: {having different compositions in a plurality of magnetic layers, e.g. layer compositions having differing elemental components or differing proportions of elements} - G11B 5/737: {Physical structure of underlayer, e.g. texture} - G11B 5/7373: {Non-magnetic single underlayer comprising chromium} - G11B 5/7379: {Seed layer, e.g. at least one non-magnetic layer is specifically adapted as a seed or seeding layer} - 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 Embodiments of the present invention help allow accurate control of the magnetization reversal in a magnetic recording layer in small reversal units, whereby high-density recording can be achieved. According to one embodiment, by forming an intermediate layer having a granular structure similar to that of the magnetic recording layer below the magnetic recording layer, a continuous crystal grain boundary is formed at the interface between the magnetic recording layer and the intermediate layer, thereby preventing incomplete formation of the crystal grain boundary found in the initial growth layer of the magnetic recording layer. The intermediate layer comprises a non-magnetic alloy comprising Co and Cr as its main components and an oxide such as Al, Cr, Hf. Mg, Nb, Si, Ta, Ti and Zr. Further, the average content of the oxygen element in the intermediate layer is in the range from 6 at % to 20 at %. ## Claims ### Claim 1 A perpendicular magnetic recording medium comprising: a substrate; an intermediate layer; a seed layer of a face-centered cubic structure positioned on a substrate side of the intermediate layer, the seed layer comprising a first layer of an alloy including Ni as its main component and materials selected from Ta and W at 10 at % or less in total, a Cu layer positioned below the first layer, and a Ti layer positioned below the Cu layer; a magnetic recording layer; and a protecting layer, said substrate layer, said intermediate layer, and said magnetic recording layer formed above the substrate, wherein: the intermediate layer comprises a mixture of a first material and a second material, the first material is a non-magnetic alloy comprising Co and Cr as its main components, the second material is an oxide, and the average content ratio of an oxygen element in the intermediate layer is in the range from 10 at % to 20 at %, and a grain diameter of crystal grains of the intermediate layer and a grain diameter of crystal grains of the magnetic recording layer are both in a range from 5 nm to 15 nm. ### Claim 2 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the magnetic recording layer includes a magnetic alloy comprising a CoCrPt alloy as its main component and an oxide. ### Claim 3 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the intermediate layer and the magnetic recording layer are disposed adjacent to each other. ### Claim 4 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein a content of the Co element in the non-magnetic alloy of the intermediate layer material is in the range from 45 at % to 65 at %. ### Claim 5 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the thickness of the intermediate layer is in the range from 2 nm to 6 nm. ### Claim 6 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the oxide of the intermediate layer material includes less than 10 mol % in total of materials selected from the group consisting of Si, Ti, and Ta. ### Claim 7 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the first material of the intermediate layer further includes materials selected from the group consisting of Pd, Ni, and Cu such that the atomic percentage of the selected materials in total is in the range from 2% to 8%. ### Claim 8 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein a soft-magnetic underlayer (customary usage) is present between the substrate and the seed layer. ### Claim 9 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the magnetic recording layer has a first recording layer comprising a magnetic alloy including a CoCrPt alloy as its main component and an oxide, and a second recording layer comprising a CoCrPt alloy as its main component and an oxide, wherein an oxide content in the second recording layer is greater than zero and less than an oxide content in the first recording layer. ### Claim 10 A magnetic recording/reproducing apparatus comprising: a magnetic recording medium; a medium driving section for driving the magnetic recording medium; a magnetic head for performing recording/reproducing operations on the magnetic recording medium; and a head driving section for positioning the magnetic head at a desired track position on the magnetic recording medium; wherein the magnetic recording medium has at least an intermediate layer, a seed layer, a magnetic recording layer, and a protecting layer formed above a substrate, in which the intermediate layer comprises a mixture of a first material and a second material, the first material is a non-magnetic alloy comprising Co and Cr as its main components, the second material is an oxide, and the average content ratio of an oxygen element in the intermediate layer is in the range from 10 at % to 20 at %, the seed layer has a face-centered cubic structure and is positioned on a substrate side of the intermediate layer, the seed layer comprising a Ti layer, a Cu layer positioned above the Ti layer, and an alloy including Ni as its main component and materials selected from Ta and W at 10 at % or less in total positioned above the Cu layer, and wherein a grain diameter of crystal grains of the intermediate layer and a grain diameter of crystal grains of the magnetic recording layer are both in a range from 5 nm to 15 nm. ### Claim 11 (depends on 1) The magnetic recording/reproducing apparatus according to claim 1 wherein the magnetic recording medium includes a soft-magnetic underlayer between the substrate and the intermediate layer. ### Claim 12 (depends on 11) A magnetic recording/reproducing apparatus according to claim 11, wherein the magnetic head includes a recording device and a reproducing device, and the recording device includes a main pole, an auxiliary pole, and a magnetic shield at the periphery of the main pole. ### Claim 13 A perpendicular magnetic recording medium comprising: a substrate; an intermediate layer; a seed layer of a face-centered cubic structure on a substrate side of the intermediate layer, the seed layer comprising a Ti layer, a Cu layer positioned above the Ti layer, and an alloy including Ni as its main component and materials selected from Ta and W at 10 at % or less in total positioned above the Cu layer, a magnetic recording layer disposed adjacent to the intermediate layer; and a protecting layer, said seed layer, said intermediate layer, and said magnetic recording layer formed above the substrate, wherein the intermediate layer comprises a mixture of a first material and a second material, wherein the first material is a non-magnetic alloy comprising Co and Cr as its main components along with materials selected from a group consisting of Pd, Ni, and Cu such that an atomic percentage of the selected materials in total is in a range from 2% to 8%, wherein the second material is an oxide with an average content ratio of an oxygen element in the intermediate layer being in a range from 10 at % to 20 at %, wherein a content of the Co element in the non-magnetic alloy of the intermediate layer material is in a range from 45 at % to 65 at %, wherein the oxide of the intermediate layer material includes less than 10 mol % in total of materials selected from a group consisting of Si, Ti, and Ta, and wherein a grain diameter of crystal grains of the intermediate layer and a grain diameter of crystal grains of the magnetic recording layer are both in a range from 5 nm to 15 nm. ### Claim 14 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the first material further comprises Pd such that an atomic percentage of the Pd in total is in a range from 2% to 8%. ### Claim 15 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein a full width at half maximum Δθ50 of a rocking curve of the intermediate layer and the magnetic recording layer is about 4° or less. ### Claim 16 (depends on 10) The magnetic recording/reproducing apparatus according to claim 10, wherein the magnetic recording medium includes a soft-magnetic underlayer between the substrate and the intermediate layer. ### Claim 17 (depends on 10) The magnetic recording/reproducing apparatus according to claim 10, wherein the magnetic head includes a recording device and a reproducing device, and the recording device includes a main pole, an auxiliary pole, and a magnetic shield at the periphery of the main pole. ### Claim 18 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the first material further comprises Pd such that an atomic percentage of the Pd in total is in a range from 2% to 8%, wherein a full width at half maximum Δθ50 of a rocking curve of the intermediate layer and the magnetic recording layer is about 4° or less, wherein a content of the Co element in the non-magnetic alloy of the intermediate layer material is in the range from 45 at % to 65 at %, wherein the thickness of the intermediate layer is in the range from 2 nm to 6 nm, and wherein the oxide of the intermediate layer material includes less than 10 mol % in total of materials selected from the group consisting of Si, Ti, and Ta. ### Claim 19 (depends on 1) The perpendicular magnetic recording medium according to claim 1, wherein the seed layer controls a crystal orientation of the intermediate layer. ### Claim 20 (depends on 10) The magnetic recording/reproducing apparatus according to claim 10, wherein the first material of the intermediate layer further includes materials selected from the group consisting of Pd, Ni, and Cu such that the atomic percentage of the selected materials in total is in the range from 2% to 8%.