# US 2021/0242279 A1 · Magnetic device including multiferroic regions and methods of forming the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242279 A1 - Document ID: US20210242279A1 - Status: Published application - Kind: A1 - Application number: 16/781,225 - Filed: 2020-02-04 - Published: 2021-08-05 - Earliest claimed: 2020-02-04 - Assignees: Western Digital Technologies, Inc. - Applicants: Western Digital Technologies, Inc., - Inventors: Bhagwati PRASAD; Alan KALITSOV - Web page: https://patentgrep.com/patent/US20210242279A1 ## CPC - G11C 11/54: using elements simulating biological cells, e.g. neuron - H10B 61/22: {of the field-effect transistor [FET] type} - G06N 3/04: Architecture, e.g. interconnection topology - G11C 11/5607: {using magnetic storage elements} - H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]} - H01F 10/3272: {by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets} - H10N 50/01: Manufacture or treatment - H10N 50/10: Magnetoresistive devices - H10N 50/85: Materials of the active region - G06N 10/40: Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - G11C: STATIC STORES (semiconductor memory devices H10B) - H10B: ELECTRONIC MEMORY DEVICES - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A magnetic device includes a first electrode, a second electrode, a plurality of magnetic junctions each containing a ferromagnetic reference layer and a ferromagnetic free layer located between the first electrode and the second electrode, and a plurality of magnetoelectric multiferroic portions having different structural defect densities located between the first electrode and the second electrode. Each of the plurality of magnetoelectric multiferroic portions is magnetically coupled to the ferromagnetic free layer of a respective one of the plurality of magnetic junctions. ## Claims ### Claim 1 A magnetic device, comprising: a first electrode; a second electrode; a plurality of magnetic junctions each comprising a ferromagnetic reference layer and a ferromagnetic free layer located between the first electrode and the second electrode; and a plurality of magnetoelectric multiferroic portions having different structural defect densities located between the first electrode and the second electrode, wherein each of the plurality of magnetoelectric multiferroic portions is magnetically coupled to the ferromagnetic free layer of a respective one of the plurality of magnetic junctions. ### Claim 2 (depends on 1) The magnetic device of claim 1, wherein the magnetic device comprises a magnetoresistive memory device, and the plurality of magnetic junctions comprise a plurality of magnetic tunnel junctions each comprising a tunnel barrier layer. ### Claim 3 (depends on 2) The magnetic device of claim 2, wherein the plurality of magnetoelectric multiferroic portions comprise a material selected from BiFeO3, h-YMnO3, BaNiF4, PbVO3, BiMnO3, LuFe2O4, HoMn2O5, h-HoMnO3, h-ScMnO3, h-ErMnO3, h-TmMnO3, h-YbMnO3, h-LuMnO3, K2SeO4, Cs2CdI4, TbMnO3, Ni3V2O8, MnWO4, CuO, ZnCr2Se4, LiCu2O2, or Ni3B7O13I. ### Claim 4 (depends on 3) The magnetic device of claim 3, wherein the plurality of magnetoelectric multiferroic portions comprise BiFeO3. ### Claim 5 (depends on 1) The magnetic device of claim 1, wherein: each of the plurality of magnetoelectric multiferroic portions has a respective canted magnetic moment direction and a respective ferroelectric polarization direction; and a relative spatial orientation between the respective canted magnetic moment direction and a respective ferroelectric polarization direction within each magnetoelectric multiferroic portion is the same. ### Claim 6 (depends on 5) The magnetic device of claim 5, wherein each magnetoelectric multiferroic portion contacts a respective ferromagnetic free layer, and has a respective out of plane component of the canted magnetic moment direction that is magnetically coupled to the respective free layer via exchange coupling or bias. ### Claim 7 (depends on 6) The magnetic device of claim 6, wherein magnetoresistance between the first electrode and the second electrode has at least three different values that depend on the respective canted magnetic moment direction of the plurality of magnetoelectric multiferroic portions and the magnetization direction of the respective magnetically coupled free layer relative to the magnetization direction of the reference layer in the same magnetic junction. ### Claim 8 (depends on 1) The magnetic device of claim 1, wherein: the first electrode comprises a bottom electrode; the second electrode comprises a top electrode located over the bottom electrode; and the plurality of magnetic junctions are located above or below the plurality of magnetoelectric multiferroic portions. ### Claim 9 (depends on 1) The magnetic device of claim 1, wherein the different structural defect densities comprise a different density of broken bonds in the different magnetoelectric multiferroic portions. ### Claim 10 (depends on 1) The magnetic device of claim 1, wherein the different structural defect densities comprise a different density of displaced atoms in a crystal lattice in the different magnetoelectric multiferroic portions. ### Claim 11 (depends on 1) The magnetic device of claim 1, wherein the different structural defect densities comprise a different density of gallium or helium atoms in the different magnetoelectric multiferroic portions. ### Claim 12 (depends on 1) The magnetic device of claim 1, wherein the plurality of magnetoelectric multiferroic portions comprise: a first magnetoelectric multiferroic portion having a first structural defect density and a first ferroelectric coercivity; and a second magnetoelectric multiferroic portion having a second structural defect density higher than the first structural defect density, and a second ferroelectric coercivity higher than the first ferroelectric coercivity. ### Claim 13 (depends on 1) The magnetic device of claim 1, wherein the plurality of magnetic junctions comprise discrete magnetic tunnel junctions that do not directly contact one another, and wherein the plurality of magnetoelectric multiferroic portions are separated by distinct boundaries. ### Claim 14 (depends on 1) The magnetic device of claim 1, wherein: the plurality of magnetoelectric multiferroic portions comprise portions without distinct boundaries within a single continuous magnetoelectric multiferroic layer having a graded structural defect density that monotonically laterally changes from one side to another; and the plurality of magnetic junctions comprise a continuous polycrystalline ferromagnetic free layer having a plurality of grains separated by domain wall grain boundaries. ### Claim 15 (depends on 1) An interconnected network of magnetic devices of claim 1 that are connected in a synaptic connection configuration. ### Claim 16 A method of forming a magnetic device, comprising: forming a bottom electrode; forming a continuous magnetoelectric multiferroic layer over the bottom electrode; forming a plurality of magnetoelectric multiferroic portions in the continuous magnetoelectric multiferroic layer by structurally damaging different portions of the continuous magnetoelectric multiferroic layer with different structural defect densities; forming a plurality of magnetic junctions located over or under the plurality of magnetoelectric multiferroic portions, wherein each of the magnetic junctions comprises a respective reference layer and a respective free layer contacting a respective one of the magnetoelectric multiferroic portions; and forming a top electrode over the bottom electrode, the plurality of magnetoelectric multiferroic portions and the plurality of magnetic junctions. ### Claim 17 (depends on 16) The method of claim 16, wherein structurally damaging different portions of the continuous magnetoelectric multiferroic layer comprises performing a different focused ion beam irradiation process in each of the plurality of magnetoelectric multiferroic portions to provide the different structural defect densities in each of the plurality of the magnetoelectric multiferroic portions. ### Claim 18 (depends on 17) The method of claim 17, wherein: the different focused ion beam irradiation processes result in at least one of a different density of broken bonds in different magnetoelectric multiferroic portions, a different density of displaced atoms in a crystal lattice in the different magnetoelectric multiferroic portions, or a different density of gallium or helium atoms in the different magnetoelectric multiferroic portions; and the different focused ion beam irradiation processes are performed on exposed different magnetoelectric multiferroic portions or through the plurality of magnetic junctions overlying the different magnetoelectric multiferroic portions. ### Claim 19 (depends on 18) The method of claim 18, wherein forming the plurality of magnetic junctions comprises forming discrete magnetic tunnel junctions that do not direct contact one another, and wherein the plurality of magnetoelectric multiferroic portions are separated by distinct boundaries. ### Claim 20 (depends on 18) The method of claim 18, wherein: the focused ion beam irradiation generates a graded structural defect density that monotonically laterally changes from one side to another within the continuous magnetoelectric multiferroic layer without distinct boundaries; and forming the plurality of magnetic junctions comprises forming a continuous magnetic tunnel junction stack over the continuous magnetoelectric multiferroic layer, wherein different regions of the continuous magnetic tunnel junction stack comprise plurality of magnetic junctions.