# US 8,147,996 B2 · Perpendicular media with dual soft magnetic layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,147,996 B2 - Document ID: US8147996B2 - Status: Granted - Kind: B2 - Application number: 11/145,938 - Filed: 2005-06-07 - Published: 2006-12-07 - Granted: 2012-04-03 - Earliest claimed: 2005-06-07 - Assignees: Seagate Technology LLC - Inventors: Qixu Chen; Charles Frederick Brucker; Chung-Hee Chang; Thomas Patrick Nolan; Samuel Dacke Harkness, IV - Web page: https://patentgrep.com/patent/US8147996B2 ## CPC - G11B 5/667: including a soft magnetic layer - G11B 5/678: {having three or more magnetic layers} - 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 recording medium having a substrate, a first soft magnetic underlayer, a second soft magnetic underlayer and a perpendicular magnetic recording layer without a spacer layer between the first and second soft magnetic underlayers is disclosed. ## Claims ### Claim 1 A perpendicular recording medium comprising: a substrate; a first soft magnetic underlayer and a second soft magnetic underlayer on the substrate without a spacer layer between the first and second soft magnetic underlayers; and a magnetic recording layer, wherein the second soft magnetic underlayer is between the first soft magnetic underlayer and the magnetic recording layer, and the first soft magnetic underlayer comprises a material with an absolute value of magnetostriction constant less than 5*10−6. ### Claim 2 (depends on 1) The perpendicular recording medium of claim 1, wherein the first and second soft magnetic underlayer are directly in contact with each other. ### Claim 3 (depends on 1) The perpendicular recording medium of claim 1, wherein the substrate is shaped as a disc and the magnetic recording layer has an easy axis of magnetization directed substantially in a radial direction of the disc shaped substrate. ### Claim 4 (depends on 1) The perpendicular recording medium of claim 1, wherein the first soft magnetic underlayer comprises CoZr5Nb4 having a thickness range of 80 to 300 nm. ### Claim 5 (depends on 1) The perpendicular recording medium of claim 1, wherein the first soft magnetic underlayer material is substantially amorphous. ### Claim 6 (depends on 1) The perpendicular recording medium of claim 1, wherein the second soft magnetic underlayer material is substantially amorphous. ### Claim 7 (depends on 1) The perpendicular recording medium of claim 1, wherein at least one of the first and second soft magnetic underlayers include oxidized material. ### Claim 8 (depends on 1) The perpendicular recording medium of claim 1, wherein the second soft magnetic underlayers comprise a material, wherein the material is selected from the group consisting of Fe CoB, FeCrCoB, FeTaC, CoFeZr, CoFeTa, FeCoZrB, FeCoC, FeCoTaZr, FeCrTaC, CoFeCrZr, CoFeCrTa, FeCoCrZrB, FeCoCrC, FeCoCrTaZr, and combinations thereof. ### Claim 9 (depends on 1) The perpendicular recording medium of claim 1, wherein the first soft magnetic underlayer material is selected from the group consisting of CoZrNb, CoZrTa, and combinations thereof. ### Claim 10 (depends on 1) The perpendicular recording medium of claim 1, wherein the first and second magnetic underlayers contain substantially no stripe domains and the combined Bst of the first soft magnetic underlayer and the second soft magnetic underlayer is greater than 0.001 Gauss*Meter. ### Claim 11 (depends on 1) The perpendicular recording medium of claim 1, wherein a total thickness of the first and second soft magnetic underlayers is greater than 200 nm. ### Claim 12 (depends on 1) The perpendicular recording medium of claim 1, further comprising a third soft underlayer between the substrate and the first soft underlayer. ### Claim 13 (depends on 1) The perpendicular recording medium of claim 1, further comprising a spacer layer and a third soft underlayer between the substrate and the first soft underlayer, wherein the spacer layer is located between the first and third soft underlayers. ### Claim 14 (depends on 1) The perpendicular recording medium of claim 1, wherein the second soft magnetic underlayer comprises FeCoB. ### Claim 15 (depends on 14) The perpendicular recording medium of claim 14, wherein the first magnetic underlayer comprises at least one of CoZrNb or CoZrTa. ### Claim 16 A perpendicular recording medium comprising: a substrate; a first soft magnetic underlayer on the substrate, the first soft magnetic underlayer comprising a material with an absolute value of magnetostriction constant less than 5*10−6; a second soft magnetic underlayer on the first soft magnetic underlayer, the second soft magnetic underlayer comprising FeCoB; and a magnetic recording layer, wherein the second soft magnetic underlayer is between the first soft magnetic underlayer and the magnetic recording layer, and the second soft underlayer provides a template for orienting the magnetic recording layer to have a growth direction with less than 4 degrees FWHM of XRD rocking curves around the (0002) peaks. ### Claim 17 (depends on 16) The perpendicular recording medium of claim 16, wherein the first soft magnetic underlayer comprises at least one of CoZrNb or CoZrTa. ### Claim 18 (depends on 16) The perpendicular recording medium of claim 16, wherein the first and second soft magnetic underlayers are not separated by a spacer layer. ### Claim 19 A perpendicular recording medium comprising: a substrate; a first soft magnetic underlayer on the substrate, the first soft magnetic underlayer comprising at least one of CoZrNb or CoZrTa; a second soft magnetic underlayer on the first soft magnetic underlayer, the second soft magnetic underlayer comprising FeCoB; and a magnetic recording layer, the second soft magnetic underlayer between the first soft magnetic underlayer and the magnetic recording layer, wherein the first soft magnetic underlayer has a magnetostriction constant less than 5*10−6, and wherein the magnetic recording layer has a growth direction with less than 4 degrees FWHM of XRD rocking curves around the (0002) peaks. ### Claim 20 (depends on 19) The perpendicular recording medium of claim 19, wherein the first and second soft magnetic underlayers are not separated by a spacer layer. ### Claim 21 (depends on 1) The perpendicular recording medium of claim 1, wherein the second soft magnetic underlayer is configured to provide a template for orienting the magnetic recording layer to have a growth direction with less than 4 degrees FWHM of XRD rocking curves around the (0002) peaks. ### Claim 22 (depends on 1) The perpendicular recording medium of claim 1, wherein the first and second soft magnetic underlayers contain substantially no stripe domains. ### Claim 23 (depends on 16) The perpendicular recording medium of claim 16, wherein the first soft magnetic underlayer has a low magnetostriction constant and the second soft magnetic underlayer has a magnetostriction constant greater than the low magnetostriction constant. ### Claim 24 (depends on 16) The perpendicular recording medium of claim 16, wherein the first and second soft magnetic underlayers contain substantially no stripe domains.