MAGNETIC SENSOR AND CURRENT SENSOR
A magnetic sensor includes a magnetoresistive effect element having a sensitivity axis in a specific direction. The magnetoresistive effect element has on a substrate, a laminate structure in which a fixed magnetic layer and a free magnetic layer are laminated with a nonmagnetic material layer interposed therebetween and includes at a side of the free magnetic layer apart from the nonmagnetic material layer, a first antiferromagnetic layer which generates an exchange coupling bias with the free magnetic layer and aligns a magnetization direction thereof in a predetermined direction in a magnetization changeable state. The free magnetic layer includes a first ferromagnetic layer in contact with the first antiferromagnetic layer to be exchange-coupled therewith and a magnetic adjustment layer at a side of the first ferromagnetic layer apart from the first antiferromagnetic layer. The magnetic adjustment layer contains at least one iron group element and at least one platinum group element.
1 . A magnetic sensor comprising:
a substrate:
a magnetoresistive effect element having a sensitivity axis in a specific direction, the magnetoresistive effect element including:
a laminate structure formed on the substrate, the laminated structure having a fixed magnetic layer, a free magnetic layer, and a nonmagnetic material layer interposed therebetween; and
a first antiferromangetic layer formed on the laminated structure and in contact with the free magnetic layer at an opposite side of the nonmagnetic material layer, the first antiferromagnetic layer generating an exchange coupling bias with the free magnetic layer and allowing a magnetization direction of the free magnetic layer to align with a predetermined direction when magnetization is changeable,
wherein the free magnetic layer includes:
a first ferromagnetic layer in contact with the first antiferromagnetic layer to have an exchange-coupling therewith; and
a magnetic adjustment layer provided on the first ferromagnetic layer at an opposite side of the first antiferromagnetic layer, the magnetic adjustment layer containing at least one iron group element and at least one platinum group element.
2 . The magnetic sensor according to claim 1 ,
wherein a Curie temperature Tc a of the magnetic adjustment layer is lower than a Curie temperature Tc 1 of the first ferromagnetic layer.
3 . The magnetic sensor according to claim 1 ,
wherein a reduction rate R Ms of a saturation magnetization Ms of the magnetic adjustment layer obtained when the temperature thereof is increased from 25° C. to 150° C. is larger than a reduction rate R Ms0 of a saturation magnetization Ms of a reference layer obtained when the temperature thereof is increased from 25° C. to 150° C., the reference layer containing an iron group element in place of every corresponding platinum group element contained in the magnetic adjustment layer.
4 . The magnetic sensor according to claim 1 ,
wherein the magnetic adjustment layer is formed of a material containing the platinum group element equal to or smaller than 40 percent by atom.
5 . The magnetic sensor according to claim 1 ,
wherein the magnetic adjustment layer is formed of a material containing the platinum group element equal to or greater than 10 percent by atom.
6 . The magnetic sensor according to claim 1 ,
wherein the free magnetic layer further includes:
a second ferromagnetic layer disposed on the magnetic adjustment layer at an opposite side of the first ferromagnetic layer.
7 . The magnetic sensor according to claim 1 ,
wherein the nonmagnetic material layer contains Cu, and a surface of the free magnetic layer in contact with the nonmagnetic material layer is formed of a ferromagnetic material containing Co and Fe.
8 . The magnetic sensor according to claim 1 ,
wherein the first antiferromagnetic layer contains a platinum group element and Mn.
9 . The magnetic sensor according to claim 1 ,
wherein the first antiferromagnetic layer is formed of at least one of IrMn and PtMn.
10 . The magnetic sensor according to claim 1 ,
wherein the fixed magnetic layer has a laminated structure including:
a first magnetic layers;
a second magnetic layer in contact with the nonmagnetic material layer; and
a nonmagnetic interlayer interposed between the first and second magnetic layers,
and wherein the fixed magnetic layer is a self-pinning type in which magnetization of the first magnetic layer and magnetization of the second magnetic layer are fixed in antiparallel to each other.
11 . The magnetic sensor according to claim 1 ,
wherein the fixed magnetic layer has a laminated structure including:
a ferromagnetic layer in contact with the non magnetic material layer; and
a second antiferromagnetic layer disposed on the ferromagnetic layer at an opposite side of the nonmagnetic material layer, the second antiferromagnetic layer generating an exchange coupling bias with the ferromagnetic layer and allowing a magnetization direction of the ferromagnetic layer to align with a predetermined direction.
12 . The magnetic sensor according to claim 1 ,
wherein in the laminate structure, the free magnetic layer is disposed between the fixed magnetic layer and the substrate.
13 . The magnetic sensor according to claim 1 ,
wherein in the laminate structure, the fixed magnetic layer is disposed between the free magnetic layer and the substrate.
14 . A current sensor comprising: the magnetic sensor according to claim 1 .