Magnetoresistive element and magnetic sensor

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.

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.

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.