# US 2014/0151828 A1 · Spin-torque magnetoresistive structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0151828 A1 - Document ID: US20140151828A1 - Status: Published application - Kind: A1 - Application number: 14/173,161 - Filed: 2014-02-05 - Published: 2014-06-05 - Earliest claimed: 2009-05-29 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Daniel Worledge - Web page: https://patentgrep.com/patent/US20140151828A1 ## CPC - H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - G11C 11/1675: {Writing or programming circuits or methods} - H10N 50/01: Manufacture or treatment - H10N 50/10: Magnetoresistive devices - H10N 52/80: Constructional details - H10B: ELECTRONIC MEMORY DEVICES - G11C: STATIC STORES (semiconductor memory devices H10B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract Magnetoresistive structures, devices, memories, and methods for forming the same are presented. For example, a magnetoresistive structure includes a first ferromagnetic layer, a first nonmagnetic spacer layer proximate to the first ferromagnetic layer, a second ferromagnetic layer proximate to the first nonmagnetic spacer layer, and a first antiferromagnetic layer proximate to the second ferromagnetic layer. For example, the first ferromagnetic layer may comprise a first pinned ferromagnetic layer, the second ferromagnetic layer may comprise a free ferromagnetic layer, and the first antiferromagnetic layer may comprise a free antiferromagnetic layer. ## Claims ### Claim 1 A magnetoresistive structure comprising: a first ferromagnetic layer; a first nonmagnetic spacer layer proximate to the first ferromagnetic layer; a second free ferromagnetic layer proximate to the first nonmagnetic spacer layer; a first free antiferromagnetic layer in physical contact with the second free ferromagnetic layer; a second nonmagnetic spacer layer in physical contact with the first free antiferromagnetic layer; and a second pinned antiferromagnetic layer in physical contact with the second nonmagnetic spacer layer. ### Claim 2 (depends on 1) The magnetoresistive structure of claim 1 further comprising: a third pinned antiferromagnetic layer proximate to and exchange coupled to the first ferromagnetic layer; and a third pinned ferromagnetic layer proximate to the second pinned antiferromagnetic layer. ### Claim 3 (depends on 1) The magnetoresistive structure of claim 1, wherein the first ferromagnetic layer comprises a first pinned ferromagnetic layer. ### Claim 4 (depends on 1) The magnetoresistive structure of claim 1, wherein the first nonmagnetic spacer layer comprises at least one of a tunneling barrier layer, magnesium oxide, and a nonmagnetic metallic layer. ### Claim 5 (depends on 1) The magnetoresistive structure of claim 1, wherein the second nonmagnetic spacer layer comprises at least one of a nonmagnetic metallic layer and a giant magnetoresistance layer. ### Claim 6 (depends on 1) The magnetoresistive structure of claim 1, wherein at least one of: i) the first antiferromagnetic layer comprises chromium, ii) the second pinned antiferromagnetic layer comprises chromium, and iii) the second nonmagnetic spacer layer comprises at least one of gold, copper, and ruthenium. ### Claim 7 (depends on 1) The magnetoresistive structure of claim 1, wherein the second free ferromagnetic layer is exchange coupled to the first free antiferromagnetic layer. ### Claim 8 (depends on 1) The magnetoresistive structure of claim 1, wherein at least one of the first antiferromagnetic layer, the second nonmagnetic spacer layer, and the second pinned antiferromagnetic layer are adapted to provide a majority of spin-torque for switching magnetic polarization of the second free ferromagnetic layer. ### Claim 9 (depends on 3) The magnetoresistive structure of claim 3, wherein the second pinned antiferromagnetic layer is pinned by at least one of: i) the third pinned ferromagnetic layer, and ii) the second pinned antiferromagnetic layer being thicker than the first free antiferromagnetic layer. ### Claim 10 (depends on 3) The magnetoresistive structure of claim 3, wherein at least one of the first ferromagnetic layer and the third pinned ferromagnetic layer comprises at least one of: i) an alloy of cobalt and iron, and ii) a plurality of sub-layers, wherein two of the plurality of sub-layers have anti-parallel magnetic moments. ### Claim 11 (depends on 1) The magnetoresistive structure of claim 1, wherein the second free ferromagnetic layer comprises an alloy comprising at least one of iron, cobalt, and nickel. ### Claim 12 (depends on 3) The magnetoresistive structure of claim 3, wherein at least one of the first free antiferromagnetic layer, the second pinned antiferromagnetic layer and the third pinned antiferromagnetic layer comprises an alloy, and wherein the alloy comprises at least one member selected from a group consisting of manganese, iridium, nickel, platinum and iron. ### Claim 13 (depends on 1) The magnetoresistive structure of claim 1 adapted for switching of magnetic moments of both the second free ferromagnetic layer and the first free antiferromagnetic layer by a write current. ### Claim 14 (depends on 1) The magnetoresistive structure of claim 1, wherein the magnitude of a write current necessary to switch a magnetic moment of the second free ferromagnetic layer is less than a comparison write current necessary to switch a comparison magnetic moment of a comparison free ferromagnetic layer in a comparison magnetoresistive structure comprising the comparison free ferromagnetic layer abutted on one side by a comparison nonmagnetic spacer layer and abutted on another side by at least one of a device terminal, another comparison nonmagnetic spacer layer and a comparison ferromagnetic layer. ### Claim 15 (depends on 1) The magnetoresistive structure of claim 1, wherein the first free antiferromagnetic layer is adapted to provide thermal stability for the second free ferromagnetic layer. ### Claim 16 A magnetoresistive memory device comprising: a first ferromagnetic layer; a first nonmagnetic spacer layer proximate to the first ferromagnetic layer; a second free ferromagnetic layer proximate to the first nonmagnetic spacer; a first free antiferromagnetic layer in physical contact with the second free ferromagnetic layer; a second nonmagnetic spacer layer in physical contact with the first free antiferromagnetic layer; and a second pinned antiferromagnetic layer in physical contact with the second nonmagnetic spacer layer; wherein the magnetoresistive memory device stores at least two data states corresponding to at least two directions of a magnetic moment. ### Claim 17 (depends on 16) The magnetoresistive memory device of claim 16, wherein at least one of the first free antiferromagnetic layer, the second nonmagnetic spacer layer, and the second pinned antiferromagnetic layer are adapted to provide a majority of spin-torque for switching magnetic polarization of the second free ferromagnetic layer. ### Claim 18 (depends on 16) The magnetoresistive memory device of claim 16, wherein data stored within a memory cell corresponds to the direction of a magnetic moment in at least one of the second free ferromagnetic layer and the first free antiferromagnetic layer. ### Claim 19 An integrated circuit comprising: a substrate; a first ferromagnetic layer; a first nonmagnetic spacer layer proximate to the first ferromagnetic layer; a second free ferromagnetic layer proximate to the first nonmagnetic spacer layer; a first free antiferromagnetic layer in physical contact with the second free ferromagnetic layer; a second nonmagnetic spacer layer in physical contact with the first free antiferromagnetic layer; and a second pinned antiferromagnetic layer in physical contact with the second nonmagnetic spacer layer. ### Claim 20 (depends on 19) The integrated circuit of claim 19, wherein at least one of the first free antiferromagnetic layer, the second nonmagnetic spacer layer, and the second pinned antiferromagnetic layer are adapted to provide a majority of spin-torque for switching magnetic polarization of the second free ferromagnetic layer. ### Claim 21 A method for forming a spin-torque structure, the method comprising the steps of: forming a first ferromagnetic layer; forming a first nonmagnetic spacer layer proximate to the first ferromagnetic layer; forming a second free ferromagnetic layer proximate to the first nonmagnetic spacer layer; forming a first free antiferromagnetic layer in physical contact with the second free ferromagnetic layer; forming a second nonmagnetic spacer layer in physical contact with the first free antiferromagnetic layer; and forming a second pinned antiferromagnetic layer in physical contact with the second nonmagnetic spacer layer.