# US 8,771,848 B2 · Bit patterned magnetic media > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,848 B2 - Document ID: US8771848B2 - Status: Granted - Kind: B2 - Application number: 11/544,634 - Filed: 2006-10-10 - Published: 2008-04-10 - Granted: 2014-07-08 - Earliest claimed: 2006-10-10 - Assignees: Seagate Technology LLC - Applicants: Erol Girt; Hans J. Richter; Alexander Y. Dobin - Inventors: Erol Girt; Hans J. Richter; Alexander Y. Dobin - Web page: https://patentgrep.com/patent/US8771848B2 ## CPC - G11B 5/855: Coating only part of a support with a magnetic layer - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - G11B 5/746: {Bit Patterned record carriers, wherein each magnetic isolated data island corresponds to a bit} - Y10T 428/2462: with partial filling of valleys on outer surface - Y10T 428/24802: Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] - 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) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A bit patterned magnetic recording medium, comprises a non-magnetic substrate having a surface; a plurality of spaced apart magnetic elements on the surface, each of the elements constituting a discrete magnetic domain or bit; and a layer of a ferromagnetic material for regulating magnetic exchange coupling between said magnetic elements. The layer has a saturation magnetization Ms ranging from about 1 to about 2,000 emu/cm3, preferably below about 400 emu/cm3, more preferably below about 200 emu/cm3, and may overlie, underlie, or at least partially fill spaces between adjacent magnetic elements. ## Claims ### Claim 1 An apparatus, comprising: (a) a plurality of spaced apart magnetic elements, each of said elements constituting a discrete magnetic domain or bit; and (b) a matrix of ferromagnetic material partially filling spaces between said magnetic elements, the matrix of ferromagnetic material comprising a property that facilitates regulation of magnetic exchange coupling between the magnetic elements. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein a layer of a second ferromagnetic material is below all of said plurality of magnetic elements. ### Claim 3 An apparatus, comprising: a substrate having a surface; a plurality of spaced apart magnetic elements on the surface, each of the magnetic elements constituting a discrete magnetic domain or bit; and at least one of a matrix of a ferromagnetic material disposed between adjacent magnetic elements of the plurality of spaced apart magnetic elements and a layer of a ferromagnetic material disposed above the magnetic elements, the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprising a property that facilitates regulation of magnetic exchange coupling between the magnetic elements. ### Claim 4 (depends on 3) The apparatus according to claim 3, wherein the property of the ferromagnetic material comprises a saturation magnetization M, ranging from about 1 to about 2,000 emu/cm3. ### Claim 5 (depends on 3) The apparatus according to claim 3, wherein the property of the ferromagnetic material comprises a saturation magnetization M below about 400 emu/cm3. ### Claim 6 (depends on 3) The apparatus according to claim 3, wherein the property of the ferromagnetic material comprises a saturation magnetization M below about 200 emu/cm3. ### Claim 7 (depends on 3) The apparatus according to claim 3, wherein the ferromagnetic material comprises a combination or alloy of at least one ferromagnetic element and at least one additional element. ### Claim 8 (depends on 3) The apparatus according to claim 3, wherein the ferromagnetic material comprises: a combination or alloy of at least one ferromagnetic element selected from the group consisting of Fe, Co, and Ni; and at least one additional element selected from the group consisting of Al, Si, Ti, V, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Ir, Pt, and Au. ### Claim 9 (depends on 3) The apparatus according to claim 3, wherein the layer of the ferromagnetic material is disposed above the magnetic elements. ### Claim 10 (depends on 3) The apparatus according to claim 3, wherein the matrix of the ferromagnetic material partially fills spaces between adjacent magnetic elements of the plurality of spaced apart magnetic elements. ### Claim 11 (depends on 3) The apparatus according to claim 3, wherein the matrix of the ferromagnetic material completely fills spaces between adjacent magnetic elements of the plurality of spaced apart magnetic elements. ### Claim 12 (depends on 3) The apparatus according to claim 3, wherein the matrix of the ferromagnetic material is disposed between the magnetic elements and a layer of the ferromagnetic material is disposed below the magnetic elements. ### Claim 13 (depends on 3) The apparatus according to claim 3, wherein each of the magnetic elements has the same structure and comprises a stack of thin film layers including at least one magnetic recording layer. ### Claim 14 (depends on 13) The apparatus according to claim 13, wherein the structure of each of the magnetic elements is selected from the group consisting of longitudinal, perpendicular, laminated, anti-ferromagnetically coupled (AFC), granular, and superlattice structures. ### Claim 15 (depends on 13) The apparatus according to claim 13, wherein the matrix of the ferromagnetic material at least partially fills spaces between adjacent stacks and a layer of the ferromagnetic material is disposed below the stacks. ### Claim 16 (depends on 13) The apparatus according to claim 13, wherein the matrix of the ferromagnetic material is disposed between the stacks and a layer of the ferromagnetic material is disposed below the stacks. ### Claim 17 (depends on 13) The apparatus according to claim 13, comprising a non-magnetic interlayer disposed between the substrate and the at least one magnetic recording layer that controls a crystallographic structure/orientation of the at least one magnetic recording layer. ### Claim 18 (depends on 17) The apparatus according to claim 17, comprising a soft magnetic underlayer (SUL) disposed between the substrate and the non-magnetic interlayer. ### Claim 19 A method of fabricating a bit patterned magnetic recording medium, comprising: forming a plurality of spaced apart magnetic elements on a surface of a substrate, each of the magnetic elements constituting a discrete magnetic domain or bit; and forming at least one of a matrix of a ferromagnetic material between adjacent magnetic elements of the plurality of spaced apart magnetic elements and a layer of a ferromagnetic material above the magnetic elements, the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprising a property that facilitates regulation of magnetic exchange coupling between the magnetic elements. ### Claim 20 (depends on 19) The method according to claim 19, wherein the ferromagnetic material comprises a saturation magnetization M, ranging from about 1 to about 2,000 emu/cm3 and is selected for one or more of reducing coercivity distribution of the magnetic elements, partially shunting magnetostatic interaction therebetween, and reducing demagnetization fields. ### Claim 21 (depends on 19) The method according to claim 19, wherein the ferromagnetic material comprises a saturation magnetization M below about 400 emu/cm3. ### Claim 22 (depends on 19) The method according to claim 19, wherein the ferromagnetic material comprises a saturation magnetization M below about 200 emu/cm3. ### Claim 23 (depends on 19) The method according to claim 19, wherein the ferromagnetic material comprises a combination or alloy of at least one ferromagnetic element and at least one additional element. ### Claim 24 (depends on 19) The method according to claim 19, wherein the ferromagnetic material comprises at least one ferromagnetic element selected from the group consisting of Fe, Co, and Ni and at least one additional element selected from the group consisting of Al, Si, Ti, V, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Ir, Pt, and Au. ### Claim 25 (depends on 19) The method according to claim 19, wherein the matrix of the ferromagnetic material is formed between the magnetic elements, and the layer of the ferromagnetic material is formed above the magnetic elements. ### Claim 26 (depends on 19) The method according to claim 19, wherein the matrix of the ferromagnetic material is formed between the magnetic elements, and a layer of the ferromagnetic material is formed below the magnetic elements. ### Claim 27 (depends on 19) The method according to claim 19, wherein forming the plurality of spaced apart magnetic elements comprises forming each of the magnetic elements with the same structure, the structure comprising a stack of thin film layers including at least one magnetic recording layer. ### Claim 28 (depends on 27) The method according to claim 27, wherein forming the plurality of spaced apart magnetic elements comprises forming each of the magnetic elements with a structure selected from the group consisting of longitudinal, perpendicular, laminated, anti-ferromagnetically coupled (AFC), granular, and superlattice structures. ### Claim 29 (depends on 27) The method according to claim 27, wherein providing the matrix of the ferromagnetic material at least partially fills spaces between adjacent stacks, and wherein the layer of the ferromagnetic material is formed above each of the stacks. ### Claim 30 (depends on 27) The method according to claim 27, wherein the matrix of the ferromagnetic material at least partially fills spaces between adjacent stacks, and a layer of the ferromagnetic material is formed below each of the stacks. ### Claim 31 (depends on 27) The method according to claim 27, wherein forming the plurality of spaced apart magnetic elements comprises forming each of the stacks to include a non-magnetic interlayer between the substrate and the at least one magnetic recording layer for controlling the crystallographic structure/orientation of the at least one magnetic recording layer. ### Claim 32 (depends on 31) The method according to claim 31, wherein forming the plurality of spaced apart magnetic elements comprises forming each of the stacks to include a soft magnetic underlayer (SUL) between the substrate and the non-magnetic interlayer. ### Claim 33 A bit patterned magnetic recording medium, comprising: a substrate having a surface; a plurality of spaced apart magnetic elements on the surface, each of the magnetic elements constituting a discrete magnetic domain or bit; and at least one of a matrix of a ferromagnetic material disposed between the magnetic elements and a layer of a ferromagnetic material disposed above the magnetic elements, the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprising a property that facilitates control of a coercivity field (HC) distribution resulting from magnetostatic interaction between the magnetic elements. ### Claim 34 (depends on 33) The medium according to claim 33, wherein the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprises a property that facilitates control of magnetostatic interaction between neighboring ones of the magnetic elements. ### Claim 35 (depends on 33) The medium according to claim 33, wherein the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprises a property that facilitates control of demagnetization fields of the bit patterned magnetic recording medium. ### Claim 36 (depends on 33) The medium according to claim 33, wherein the at least one of the matrix of the ferromagnetic material and the layer of the ferromagnetic material comprises a property that facilitates control of thermal stability of the magnetic elements. ### Claim 37 (depends on 33) The medium according to claim 33, wherein the property of the ferromagnetic material comprises a saturation magnetization M, ranging from about 1 to about 2,000 emu/cm3.