# US 2017/0288133 A1 · Magnetoresistive element and magnetic sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288133 A1 - Document ID: US20170288133A1 - Status: Published application - Kind: A1 - Application number: 15/460,797 - Filed: 2017-03-16 - Published: 2017-10-05 - Earliest claimed: 2016-03-30 - Assignees: TDK Corporation - Applicants: TDK Corporation - Inventors: Hayato KOIKE - Web page: https://patentgrep.com/patent/US20170288133A1 ## CPC - H10N 50/10: Magnetoresistive devices - G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)} - G01R 33/098: {comprising tunnel junctions, e.g. tunnel magnetoresistance sensors} - H10N 50/80: Constructional details - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A magnetoresistive element includes a channel layer, a first ferromagnetic layer, a second ferromagnetic layer, and a reference electrode. The first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode are apart from each other and are electrically connected to each other through the channel layer. The effective cross-sectional area of a sixth region according to a plane perpendicularly intersecting a spin-polarized carrier transport path in the sixth region is smaller than the effective cross-sectional area of a seventh region according to a plane perpendicularly intersecting a voltage detection path in the seventh region. ## Claims ### Claim 1 A magnetoresistive element comprising: a channel layer; a first ferromagnetic layer; a second ferromagnetic layer; and a reference electrode, wherein the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode are apart from each other and are electrically connected to each other through the channel layer; the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode do not overlap each other and are apart from each other when viewed in a thickness direction of the channel layer; the channel layer includes a first region that overlaps the first ferromagnetic layer when viewed in the thickness direction, a second region that overlaps the second ferromagnetic layer when viewed in the thickness direction, a third region that overlaps the reference electrode when viewed in the thickness direction, a fourth region located between the first region and the second region, and a fifth region located between the second region and the third region; the second region is located between the first region and the third region in the channel layer; and supposing that a region composed of the first region, the second region, and the fourth region is a sixth region and a region composed of the second region, the third region, and the fifth region is a seventh region, an average cross-sectional area of the sixth region according to a first plane which perpendicularly intersects a shortest path in the channel layer between an end surface of the first region that faces a surface of the first region that is in contact with the fourth region and an end surface of the second region that faces a surface of the second region that is in contact with the fourth region is smaller than an average cross-sectional area of the seventh region according to a second plane which perpendicularly intersects a shortest path in the channel layer between an end surface of the second region that faces a surface of the second region that is in contact with the fifth region and an end surface of the third region that faces a surface of the third region that is in contact with the fifth region. ### Claim 2 (depends on 1) The magnetoresistive element according to claim 1, further comprising an eighth region in the fifth region, an average cross-sectional area of the eighth region according to the second plane being smaller than that of the seventh region. ### Claim 3 (depends on 2) The magnetoresistive element according to claim 2, wherein the second region is in contact with the eighth region. ### Claim 4 A magnetoresistive element comprising: a channel layer; a first ferromagnetic layer; a second ferromagnetic layer; and a reference electrode, wherein the first: ferromagnetic layer and the second ferromagnetic layer are apart from each other and are electrically connected to each other through the channel layer; the reference electrode is placed on a side surface of the channel layer so as to be apart from the first ferromagnetic layer and the second ferromagnetic layer and is electrically connected to the first ferromagnetic layer and the second ferromagnetic layer through the channel layer; the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode do not overlap each other and are apart from each other when viewed in a thickness direction of the channel layer; the channel layer includes a first region that overlaps the first ferromagnetic layer when viewed in the thickness direction, a second region that overlaps the second ferromagnetic layer when viewed in the thickness direction, a third region located between the second region and the side surface on which the reference electrode is placed, and a fourth region located between the first region and the second region; the second region is located between the first region and the third region in the channel layer; and supposing that a region composed of the first region, the second region, and the fourth region is a fifth region and a region composed of the second region and the third region is a sixth region, an average cross-sectional area of the fifth region according to a third plane which perpendicularly intersects a shortest path in the channel layer between an end surface of the first region that faces a surface of the first region that is in contact with the fourth region and an end surface of the second region that faces a surface of the second region that is in contact with the fourth region is smaller than an average cross-sectional area of the sixth region according to a fourth plane which perpendicularly intersects a shortest path in the channel layer between an end surface of the second region that faces a surface of the second region that is in contact with the third region and the side surface. ### Claim 5 (depends on 4) The magnetoresistive element according to claim 4, further comprising a seventh region in the third region, an average cross-sectional area of the seventh region according to the fourth plane being smaller than that of the sixth region. ### Claim 6 (depends on 5) The magnetoresistive element according to claim 5, wherein the second region is in contact with the seventh region. ### Claim 7 A magnetoresistive element comprising: a channel layer; a first ferromagnetic layer; a second ferromagnetic layer; and a reference electrode, wherein the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode are apart from each other and are electrically connected to each other through the channel layer; the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode do not overlap each other and are apart from each other when viewed in a thickness direction of the channel layer; the channel layer includes a first region that overlaps the first ferromagnetic layer when viewed in the thickness direction, a second region that overlaps the second ferromagnetic layer when viewed in the thickness direction, a third region that overlaps the reference electrode when viewed in the thickness direction, a fourth region located between the first region and the second region, and a fifth region located between the second region and the third region; the second region is located between the first region and the third region in the channel layer; and supposing that a region composed of the first region, the second region, and the fourth region is a sixth region and a region composed of the second region, the third region, and the fifth region is a seventh region, an effective cross-sectional area of the sixth region according to a plane perpendicularly intersecting a spin-polarized carrier transport path in the sixth region is smaller than an effective cross-sectional area of the seventh region according to a plane perpendicularly intersecting a voltage detection path in the seventh region. ### Claim 8 A magnetoresistive element comprising: a channel layer; a first ferromagnetic layer; a second ferromagnetic layer; and a reference electrode, wherein the first ferromagnetic layer and the second ferromagnetic layer are apart from each other and are electrically connected to each other through the channel layer; the reference electrode is placed on a side surface of the channel layer so as to be apart from the first ferromagnetic layer and the second ferromagnetic layer and is electrically connected to the first ferromagnetic layer and the second ferromagnetic layer through the channel layer; the first ferromagnetic layer, the second ferromagnetic layer, and the reference electrode do not overlap each other and are apart from each other when viewed in a thickness direction of the channel layer; the channel layer includes a first region that overlaps the first ferromagnetic layer when viewed in the thickness direction, a second region that overlaps the second ferromagnetic layer when viewed in the thickness direction, a third region located between the second region and the side surface on which the reference electrode is placed, and a fourth region located between the first region and the second region; the second region is located between the first region and the third region in the channel layer; and supposing that a region composed of the first region, the second region, and the fourth region is a fifth region and a region composed of the second region and the third region is a sixth region, an effective cross-sectional area of the fifth region according to a plane perpendicularly intersecting a spin-polarized carrier transport path in the fifth region is smaller than an effective cross-sectional area of the sixth region according to a plane perpendicularly intersecting a voltage detection path in the sixth region. ### Claim 9 (depends on 1) A magnetic sensor comprising the magnetoresistive element according to claim 1. ### Claim 10 (depends on 4) A magnetic sensor comprising the magnetoresistive element according to claim 4. ### Claim 11 (depends on 7) A magnetic sensor comprising the magnetoresistive according to claim 7. ### Claim 12 (depends on 8) A magnetic sensor comprising the magnetoresistive according to claim 8.