# US 6,721,137 B1 · Magnetoresistance device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,721,137 B1 - Document ID: US6721137B1 - Status: Granted - Kind: B1 - Application number: 09/549,232 - Filed: 2000-04-13 - Granted: 2004-04-13 - Earliest claimed: 1999-04-16 - Assignees: Canon Kabushiki Kaisha - Inventors: Takashi Ikeda - Web page: https://patentgrep.com/patent/US6721137B1 ## CPC - H01F 10/3268: {the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - G11C 11/1673: {Reading or sensing circuits or methods} - H10N 50/10: Magnetoresistive devices - G11B 5/3903: {using magnetic thin film layers or their effects, the films being part of integrated structures} - G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices} - Y10T 428/1121: Multilayer - Y10T 428/24942: including components having same physical characteristic in differing degree - Y10T 428/24975: No layer or component greater than 5 mils thick - Y10T 428/256: Heavy metal or aluminum or compound thereof - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G11C: STATIC STORES (semiconductor memory devices H10B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - 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) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A magnetoresistance device having a relatively high magnetoresistance ratio enables scale-down and low-current driving, and reduces deterioration of recording storage performance. The magnetoresistance device includes a substrate and a multi-layer film having a first magnetic layer, a second magnetic layer, a non-magnetic layer, a third magnetic layer and a fourth magnetic layer which are superposed on the substrate in this order. The first magnetic layer is exchange-coupled with the second magnetic layer, and the third magnetic layer is exchange coupled with the fourth magnetic layer. The first magnetic layer and the fourth magnetic layer have a magnetic anisotropy in the film-plane normal direction. ## Claims ### Claim 1 A magnetoresistance device comprising: a multi-layer film having a first magnetic layer, a second magnetic layer, a non-magnetic layer, a third magnetic layer and a fourth magnetic layer which are superposed in this order, wherein the first magnetic layer is exchange-coupled with the second magnetic layer, forming a first exchange-coupled film, the third magnetic layer is exchange-coupled with the fourth magnetic layer, forming a second exchange-coupled film, magnetization directions of the first magnetic layer and the fourth magnetic layer are oriented perpendicular to the respective film planes, and the second magnetic layer and the third magnetic layer have a higher spin polarization ratio than the first magnetic layer and the fourth magnetic layer. ### Claim 2 (depends on 1) The magnetoresistance device according to claim 1, wherein the first magnetic layer and the fourth magnetic layer each comprise an alloy of a rare-earth metal and a transition metal. ### Claim 3 (depends on 1) The magnetoresistance device according to claim 1, wherein the second magnetic layer and the third magnetic layer each comprise a transition metal. ### Claim 4 (depends on 1) The magnetoresistance device according to claim 1, wherein the magnetization of the first magnetic layer and the second magnetic layer and the magnetization of the third magnetic layer and the fourth magnetic layer are antiparallel to each other. ### Claim 5 (depends on 4) The magnetoresistance device according to claim 4, wherein the magnetization of the first magnetic layer and the second magnetic layer and the magnetization of the third magnetic layer and the fourth magnetic layer reverse simultaneously in their respective desired applied magnetic fields. ### Claim 6 (depends on 1) The magnetoresistance device according to claim 1, wherein the non-magnetic layer comprises a conductor. ### Claim 7 (depends on 1) The magnetoresistance device according to claim 1, wherein the non-magnetic layer comprises an insulator. ### Claim 8 (depends on 1) The magnetoresistance device according to claim 1, wherein magnetizations of the second magnetic layer and the third magnetic layer are oriented in a direction perpendicular to a film plane by exchange-couplings with the first magnetic layer and the fourth magnetic layer, respectively. ### Claim 9 (depends on 1) A magnetoresistance device according to claim 1, wherein the first exchange-coupled film has a coercivity larger than that of the second exchange-coupled film. ### Claim 10 A magnetoresistance device comprising: a multi-layer film having a first magnetic layer, a second magnetic layer, a non-magnetic layer, a third magnetic layer and a fourth magnetic layer which are superposed in this order, wherein the first magnetic layer is exchange-coupled with the second magnetic layer, the third magnetic layer is exchange-coupled with the fourth magnetic layer, the first magnetic layer and the fourth magnetic layer each comprise an alloy of a rare-earth metal and a transition metal, magnetization directions of the first magnetic layer and the fourth magnetic layer are oriented perpendicular to the respective film planes, the second magnetic layer and the third magnetic layer each comprise a transition metal and have a higher spin polarization ratio than the first magnetic layer and the fourth magnetic layer, and the non-magnetic layer comprises an insulator. ### Claim 11 A magnetoresistance device comprising: a multi-layer film having a first magnetic layer, a second magnetic layer, a non-magnetic layer, a third magnetic layer and a fourth magnetic layer which are superposed in this order, wherein the magnetization direction of the second magnetic layer is perpendicular to the film plane by exchange-coupling with the first magnetic layer, the magnetization direction of the third magnetic layer is perpendicular to the film plane by exchange-coupling with the fourth magnetic layer, and the second magnetic layer and the third magnetic layer have a higher spin polarization ratio than the first magnetic layer and the fourth magnetic layer.