# US 8,147,995 B2 · Patterned media bits with cladding shell > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,147,995 B2 - Document ID: US8147995B2 - Status: Granted - Kind: B2 - Application number: 12/496,505 - Filed: 2009-07-01 - Published: 2010-02-11 - Granted: 2012-04-03 - Earliest claimed: 2008-08-06 - Assignees: Seagate Technology LLC - Inventors: Haiwen Xi; Kaizhong Gao; Song S. Xue - Web page: https://patentgrep.com/patent/US8147995B2 ## CPC - G11B 5/82: Disk carriers - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - G11B 5/743: {Patterned record carriers, wherein the magnetic recording layer is patterned into magnetic isolated data islands, e.g. discrete tracks} - G11B 5/746: {Bit Patterned record carriers, wherein each magnetic isolated data island corresponds to a bit} - G11B 5/855: Coating only part of a support with a magnetic 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) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract A bit patterned media (BPM) includes many magnetic dots arranged in tracks on a substrate. The magnetic dots each have a hard magnetic core, a soft magnetic cladding surrounding the core and a thin non-magnetic layer that separates the hard magnetic core from the soft magnetic ring. The soft magnetic cladding stabilizes the magnetization at the edges of the hard magnetic core to improve the signal to noise ratio of the magnetic dots. The soft magnetic rings also narrow the magnetic field of the dots which reduces the space requirements and allows more dots to be placed on the substrate. ## Claims ### Claim 1 A magnetic storage device, comprising, a plurality of spaced apart magnetic bits, each bit constituting a discrete magnetic domain on a planar surface, each bit comprises a hard magnetic core with an external surface, a non-magnetic spacer laterally in contact with the external surface of the core and a magnetically soft cladding surrounding the non-magnetic spacer wherein the non-magnetic spacer and the soft magnetic cladding are configured such that the hard magnetic core and the soft magnetic cladding are operable to anti-ferromagnetically couple with each other. ### Claim 2 (depends on 1) The magnetic storage device of claim 1 wherein the soft cladding includes a soft magnetic ring, the hard magnetic core has a circular cross section with a diameter, and the soft magnetic ring has a horizontal width is between 5% and 25% of the diameter of the hard magnetic core. ### Claim 3 (depends on 1) The magnetic storage device of claim 1 wherein the hard magnetic cores are circular in cross section and less than 20 nanometers in diameter. ### Claim 4 (depends on 1) The magnetic storage device of claim 1 wherein the soft cladding includes a soft magnetic ring having a horizontal width less than 2 nanometers. ### Claim 5 (depends on 1) The magnetic storage device of claim 1 wherein the non-magnetic spacers include ruthenium (Ru). ### Claim 6 (depends on 1) The device of claim 1 wherein the plurality of magnetic bits are arranged in a plurality of tracks on a substrate and the plurality of magnetic bits in one of the tracks are offset from the plurality of magnetic bits in an adjacent track. ### Claim 7 (depends on 1) The magnetic storage device of claim 1 wherein the hard magnetic cores each have a first magnetization direction perpendicular to the planar surface and each of the soft magnetic claddings have a magnetization direction perpendicular to the planar surface and opposite the first direction. ### Claim 8 A method, comprising: on a planar surface of a substrate, forming a plurality of spaced apart magnetic bits, each bit comprising a hard magnetic core with a first magnetization direction perpendicular to the plane surface; forming a thin non-magnetic spacer layer around a lateral surface of each of the hard magnetic cores; and forming a soft magnetic cladding disposed around a lateral surface of each of the space layers, the magnetic cladding having a second magnetization direction perpendicular to the planar surface and opposite of the first direction. ### Claim 9 (depends on 8) The method of claim 8 further comprising: planarizing upper surfaces of the hard magnetic cores. ### Claim 10 (depends on 8) The method of claim 8, wherein the forming of the plurality of soft magnetic rings comprises depositing a layer of soft magnetic material onto the substrate and etching the soft magnetic material between the plurality of spaced apart hard magnetic cores. ### Claim 11 (depends on 10) The method of claim 10 wherein the etching is performed by ion milling. ### Claim 12 (depends on 8) The method of claim 8 wherein the forming the non-magnetic spacers includes depositing a layer of non-magnetic material onto the substrate. ### Claim 13 (depends on 8) The method of claim 8 further comprising: depositing a non-magnetic material on the substrate between the plurality of soft magnetic rings. ### Claim 14 (depends on 8) The method of claim 8 further comprising: depositing a protective layer over the plurality of spaced apart hard magnetic cores and the non-magnetic material on the substrate between the plurality of soft magnetic rings. ### Claim 15 A magnetic storage device, comprising: a magnetic bit comprising: a hard magnetic core with an external surface; a non-magnetic spacer laterally in contact with the external surface of the hard magnetic core; and a soft magnetic cladding surrounding the thin non-magnetic spacer; wherein the non-magnetic spacer and the soft magnetic cladding are configured such that the hard magnetic core and the soft magnetic cladding are operable to anti-ferromagnetically couple with each other. ### Claim 16 (depends on 15) The magnetic storage device of claim 15 wherein the soft magnetic cladding includes a soft magnetic cladding, the hard magnetic core has a circular cross section, and the soft magnetic ring has a horizontal width is between 5% and 25% of a diameter of the hard magnetic core. ### Claim 17 (depends on 15) The magnetic storage device of claim 15 wherein the hard magnetic cores are circular in cross section and less than 20 nanometers in diameter. ### Claim 18 (depends on 15) The magnetic storage device of claim 15 wherein the soft magnetic rings have a horizontal width less than 2 nanometers. ### Claim 19 (depends on 15) The magnetic storage device of claim 15 wherein the non-magnetic spacers include ruthenium (Ru). ### Claim 20 (depends on 15) The magnetic storage device of claim 15 wherein the hard magnetic core has a first perpendicular magnetization direction and the soft magnetic cladding has a perpendicular magnetization direction opposite the first direction.