# US 8,786,988 B2 · Read sensor having a structure for reducing magnetic coupling between a magnetic bias layer and an upper magnetic shield > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,988 B2 - Document ID: US8786988B2 - Status: Granted - Kind: B2 - Application number: 13/472,326 - Filed: 2012-05-15 - Published: 2013-11-21 - Granted: 2014-07-22 - Earliest claimed: 2012-05-15 - Assignees: HGST Netherlands B.V. - Applicants: Hideki Mashima; Nobuo Yoshida; Takahiro Ibusuki; Tsutomu Yasuda - Inventors: Hideki Mashima; Nobuo Yoshida; Takahiro Ibusuki; Tsutomu Yasuda - Web page: https://patentgrep.com/patent/US8786988B2 ## CPC - G11B 5/3932: {Magnetic biasing films} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - G11B 5/3909: {Arrangements using a magnetic tunnel junction} - G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices} - Y10T 29/49034: Treating to affect magnetic properties - 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 magnetic sensor having reduced read gap thickness, reduced signal noise and improved signal to noise ratio. The sensor includes a sensor stack and hard bias structures formed at either side of the sensor stack for biasing the free layer of the sensor. A protective layer is formed over a portion of the hard bias structure, however a portion of the hard bias structure extends upward toward the upper shield and is disposed between the protective layer and the sensor stack as a result of the process used to form the magnetic bias structure. This portion of the hard bias structure that extends toward the upper shield has a reduced magnetization relative to the rest of the hard bias structure so that it will not magnetically couple with the upper shield. ## Claims ### Claim 1 A magnetic sensor, comprising: first and second, electrically conductive magnetic shields; a sensor stack sandwiched between the first and second magnetic shields, the sensor stack having first and second laterally opposed sides; first and second magnetic biasing layers extending laterally from the first and second sides of the sensor stack; first and second non-magnetic protective layers each being located between the second electrically conductive shield and one of the first and second magnetic layers; wherein the magnetic bias layer has a tail portion that extends toward the second shield and is disposed between the non-magnetic protective layer and the sensor stack, the tail portion being demagnetized. ### Claim 2 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layers has a non-magnetic element infused therein. ### Claim 3 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layers has nitrogen atoms diffused therein. ### Claim 4 (depends on 1) The magnetic read sensor as in claim 1 wherein each of the magnetic bias layers is separated from the sensor stack by a thin layer of electrically insulating material. ### Claim 5 (depends on 1) The magnetic read sensor as in claim 1 wherein each of the magnetic bias layers is separated from the sensor stack by a thin layer of alumina. ### Claim 6 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layers extends to the second electrically conductive magnetic shield. ### Claim 7 (depends on 1) The magnetic read sensor as in claim 1 further comprising a non-magnetic gap layer disposed between the second electrically conductive shield and the sensor stack, tail portion of the magnetic bias material and non-magnetic protective layer. ### Claim 8 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of the magnetic bias layer comprises CoPt with a non-magnetic element infused therein and the rest of the magnetic bias layer comprises CoPt. ### Claim 9 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of the magnetic bias layer comprises CoPtCr with a non-magnetic element infused therein and the rest of the magnetic bias layer comprises CoPtCr. ### Claim 10 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of the magnetic bias layer comprises CoPt with nitrogen infused therein and the rest of the magnetic bias layer comprises CoPt. ### Claim 11 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of the magnetic bias layer comprises CoPtCr with nitrogen infused therein and the rest of the magnetic bias layer comprises CoPtCr. ### Claim 12 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layer has one or more of the following in fused therein: O, N, Ar, Xe, Cr, Ta, and C. ### Claim 13 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layers comprises CoPt and one or more of the following: O, N, Ar, Xe, Cr, Ta, and C. ### Claim 14 (depends on 1) The magnetic read sensor as in claim 1 wherein the tail portion of each of the magnetic bias layers comprises CoPtCr and one or more of the following: O, N, Ar, Xe, Cr, Ta, and C.