# US 10,312,436 B2 · Ground state artificial skyrmion lattices at room temperature > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,436 B2 - Document ID: US10312436B2 - Status: Granted - Kind: B2 - Application number: 15/880,916 - Filed: 2018-01-26 - Published: 2018-08-23 - Granted: 2019-06-04 - Earliest claimed: 2015-08-05 - Assignees: The Regents of the University of California - Applicants: The Regents of the University of California - Inventors: Dustin Gilbert; Kai Liu - Web page: https://patentgrep.com/patent/US10312436B2 ## CPC - H10N 50/01: Manufacture or treatment - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - H01F 10/3286: {Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy} - H01F 41/14: for applying magnetic films to substrates - H10N 50/10: Magnetoresistive devices - H10N 50/85: Materials of the active region - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature and in the absence of magnetic fields is provided. The lattices are formed by patterning vortex-state nanodots over macroscopic areas on top of an underlayer with perpendicular magnetic anisotropy (PMA); and preparing artificial skyrmion lattices using ion irradiation to suppress PMA in the underlayer and allow imprinting of the vortex structure from the nanodots to form the skyrmion lattices. Alternatively the skyrmions can be formed by ion-irradiating select asymmetric nanodot regions of the PMA underlayer, leading to planar skyrmions without nanodot protrusions. These artificial skyrmions can be used for low dissipation information storage, such as magnetic memory, logic devices and sensors. ## Claims ### Claim 1 A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature, the method comprising: (a) providing a substrate with an underlayer with perpendicular magnetic anisotropy (PMA); (b) applying a template layer to a top surface of the underlayer; (c) patterning the template layer with one or more asymmetrically shaped openings exposing the underlayer; (d) irradiating the exposed underlayer with ions; (e) forming asymmetrically shaped structures on the irradiated underlayer; (f) removing the template layer; and (g) setting the skyrmion state. ### Claim 2 (depends on 1) The method of claim 1, further comprising coupling the substrate to a silicon support base. ### Claim 3 (depends on 1) The method of claim 1, wherein the skyrmion state is set by performing steps comprising: (a) saturating the underlayer in a positive out-of-plane (+OOP) direction; (b) applying a static field in a negative out-of-plane (−OOP) direction that is weaker than a reversal field of the underlayer so that the underlayer remains positively saturated; (c) applying a moderate in plane (IP) field parallel to a flat edge of the asymmetric structures, driving them to a saturated state; (d) wherein removing the IP field facilitates the nucleation of a vortex in each of the asymmetric structures with a well-defined circularity; and (e) wherein the static out-of-plane field biases the vortex core polarity at the nucleation event to be opposite to the underlayer, defining the polarity. ### Claim 4 (depends on 1) The method of claim 1, wherein said substrate underlayer with perpendicular magnetic anisotropy comprises alternating layers of cobalt and palladium. ### Claim 5 (depends on 1) The method of claim 1, wherein said substrate underlayer comprises alternating layers of materials selected from the group of materials consisting of Co/Pt, Co/Ni, and CoFeB/MgO. ### Claim 6 (depends on 1) The method of claim 1, wherein said substrate underlayer is a material selected from the group of materials consisting of FePt, FePd, CoPt, CoPd, GdFeCo, and TbFeCo. ### Claim 7 (depends on 1) The method of claim 1, wherein said template layer comprises a polymer layer configured for e-beam lithography. ### Claim 8 (depends on 1) The method of claim 1, wherein said template layer comprises a photoresist layer configured for photolithography. ### Claim 9 (depends on 1) The method of claim 1, wherein the asymmetrically shaped structures are formed from a ferromagnetic metal material selected from the group of materials consisting of Fe, Ni, Gd, Sm, Tb, Nd, Mn and their alloys. ### Claim 10 (depends on 1) The method of claim 1, wherein the asymmetrically shaped structures are formed from an intermetallic material selected from the group of materials consisting of FeGa and NdFeB. ### Claim 11 (depends on 1) The method of claim 1, wherein the asymmetrically shaped structures are formed from a ferromagnetic oxide material selected from the group of materials consisting of LaSrMnO3 and LaSrCoO3. ### Claim 12 (depends on 1) The method of claim 1, wherein the asymmetrically shaped structures are formed from a ferromagnetic nitride material selected from the group of materials consisting of FeN and GdN. ### Claim 13 (depends on 1) The method of claim 1, wherein said asymmetric structure has a cross-sectional shape selected from the group of shapes consisting of an edge cut circle, a triangle, a pentagon and a heptagon. ### Claim 14 (depends on 1) The method of claim 1, wherein said asymmetric structure comprises an asymmetric edge-cut circle with an arm extending radially from the center of the edge-cut circle. ### Claim 15 (depends on 14) The method of claim 14, further comprising: applying at least one contact pad to the arm of the asymmetric structure configured to allow the introduction of partially spin-polarized current to drive the skyrmions along the length of the arm. ### Claim 16 A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature, the method comprising: (a) providing a substrate with a support base and an active layer with perpendicular magnetic anisotropy (PMA); (b) irradiating parts of the active layer with ions; (c) embedding one or more asymmetrically shaped structures into irradiated parts of a top surface of the active layer; and (d) setting the skyrmion state. ### Claim 17 (depends on 16) The method of claim 16, wherein the skyrmion state is set by performing steps comprising: (a) saturating the active layer in a positive out-of-plane (+OOP) direction; (b) applying a static field in a negative out of plane (−OOP) direction that is weaker than a reversal field of the active layer so that the active layer remains positively saturated; (c) applying a moderate in plane (IP) field parallel to a flat edge of the asymmetric structures, driving them to a saturated state; (d) wherein removing the IP field facilitates the nucleation of a vortex in each of the asymmetric structures with a well-defined circularity; and (e) wherein the static out-of-plane field biases the vortex core polarity at the nucleation event to be opposite to the active layer thereby defining the polarity. ### Claim 18 (depends on 16) The method of claim 16, wherein said active layer comprises alternating layers of materials selected from the group of materials consisting of Co/Pd, Co/Pt, Co/Ni, and CoFeB/MgO. ### Claim 19 (depends on 16) The method of claim 16, wherein said substrate underlayer is a material selected from the group of materials consisting of FePt, FePd, CoPt, CoPd, GdFeCo, and TbFeCo. ### Claim 20 (depends on 16) The method of claim 16, wherein said embedded asymmetric structure has a cross-sectional shape selected from the group of shapes consisting of an edge cut circle, a triangle, a pentagon and a heptagon. ### Claim 21 A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature, the method comprising: (a) providing a substrate with a support base and an underlayer with perpendicular magnetic anisotropy (PMA); (b) applying a template layer to a top surface of the underlayer; (c) patterning the template layer with one or more asymmetrically shaped openings exposing the underlayer; (d) irradiating the exposed underlayer with ions; (e) forming asymmetrically shaped structures on the irradiated underlayer, said asymmetric structure comprising an asymmetric edge-cut circle with an arm extending radially from the center of the edge-cut circle; (f) removing the template layer; (g) applying at least one contact pad to the arm of the asymmetric structure configured to allow the introduction of partially spin-polarized current to drive the skyrmions along the length of the arm; and (h) setting the skyrmion state. ### Claim 22 (depends on 21) The method of claim 21, wherein the skyrmion state is set by performing steps comprising: (a) saturating the active layer in a positive out-of-plane (+OOP) direction; (b) applying a static field in a negative out of plane (−OOP) direction that is weaker than a reversal field of the active layer so that the active layer remains positively saturated; (c) applying a moderate in plane (IP) field parallel to a flat edge of the asymmetric structures, driving them to a saturated state; (d) wherein removing the IP field facilitates the nucleation of a vortex in each of the asymmetric structures with a well-defined circularity; and (e) wherein the static out of plane field biases the vortex core polarity at the nucleation event to be opposite to the active layer thereby defining the polarity. ### Claim 23 (depends on 17) The method of claim 17, wherein said active layer comprises of materials selected from the group of materials consisting of Co/Pd, Co/Pt, Co/Ni, CoFeB/MgO, FePt, FePd, CoPt, CoPd, GdFeCo, and TbFeCo. ### Claim 24 (depends on 21) The method of claim 21, wherein said template layer comprises a polymethyl methacrylate (PMMA) polymer layer configured for e-beam lithography.