JP-2026074774-A - Magnetoresistive elements, magnetic sensors, and detectors

JP2026074774AJP 2026074774 AJP2026074774 AJP 2026074774AJP-2026074774-A

Abstract

[Problem] To provide a magnetoresistive element that can respond to a wide range of magnetic fields. [Solution] The magnetoresistive element 100 comprises a first magnetic layer 11, a second magnetic layer 12, and a third magnetic layer 13 whose magnetization direction changes in response to an external magnetic field, a first non-magnetic layer 31 located between the first magnetic layer 11 and the third magnetic layer 13, and a dielectric layer 20 located between the first magnetic layer 11 and the second magnetic layer 12. The first magnetic layer 11 is located between the second magnetic layer 12 and the third magnetic layer 13. The first magnetic layer 11 and the third magnetic layer 13 are antiferromagnetically exchanged-coupled via the first non-magnetic layer 31. The magnetization direction D1 of the first magnetic layer 11 and the magnetization direction D2 of the second magnetic layer 12 are stabilized in an antiparallel state when no external magnetic field is applied. [Selection Diagram] Figure 1

Inventors

西谷雄
中谷友也

Assignees

国立研究開発法人物質・材料研究機構
パナソニックホールディングス株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (15)

A first magnetic layer, a second magnetic layer, and a third magnetic layer whose magnetization direction changes in response to an external magnetic field, wherein the first magnetic layer is laminated so as to be located between the second magnetic layer and the third magnetic layer, A first non-magnetic layer located between the first magnetic layer and the third magnetic layer, A dielectric layer located between the first magnetic layer and the second magnetic layer, The first magnetic layer and the third magnetic layer are antiferromagnetically exchanged and coupled through the first nonmagnetic layer. The magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer stabilize in an antiparallel state when no external magnetic field is applied. Magnetoresistive element.
The dielectric layer mainly comprises magnesium oxide, aluminum oxide, or magnesium-aluminum oxide. The magnetoresistive element according to claim 1.
Each of the first magnetic layer and the second magnetic layer has an alloy layer mainly composed of an alloy of cobalt, iron, and boron. The magnetoresistive element according to claim 1.
The first non-magnetic layer contains ruthenium as its main component, The thickness of the first non-magnetic layer is 0.6 mm or more and 0.9 mm or less. The magnetoresistive element according to claim 1.
The present invention further comprises a fourth magnetic layer and a fifth magnetic layer whose magnetization direction is fixed in one direction, The fourth magnetic layer faces the first non-magnetic layer via the third magnetic layer, The fifth magnetic layer faces the dielectric layer via the second magnetic layer, The magnetoresistive element according to claim 1.
The third magnetic layer and the fourth magnetic layer are antiferromagnetically exchanged and coupled. The second magnetic layer and the fifth magnetic layer are antiferromagnetically exchanged and coupled. The magnetoresistive element according to claim 5.
A first antiferromagnetic layer facing the third magnetic layer via the fourth magnetic layer, The present invention further comprises a second antiferromagnetic layer facing the second magnetic layer via the fifth magnetic layer, The magnetoresistive element according to claim 5.
Each of the first antiferromagnetic layer and the second antiferromagnetic layer mainly contains a manganese-iridium alloy, a manganese-platinum alloy, or a manganese-nickel alloy. The magnetoresistive element according to claim 7.
The first antiferromagnetic layer, The fourth magnetic layer, The second non-magnetic layer, The third magnetic layer, The first non-magnetic layer, The first magnetic layer and Dielectric layer and The second magnetic layer and The third non-magnetic layer, The fifth magnetic layer, It has a stacked structure in which a second antiferromagnetic layer and a second antiferromagnetic layer are stacked in this order. The first non-magnetic layer is formed such that the first magnetic layer and the third magnetic layer exhibit a first-order antiferromagnetic RKKY (Rudeman, Kittel, Kasuya, Yoshida) interaction. Magnetoresistive element.
A magnetoresistive element according to any one of claims 1 to 9, A first electrode electrically connected to one end of the magnetoresistive element, A second electrode electrically connected to the other end of the magnetoresistive element, Magnetic sensor.
The system detects magnetic field components in directions different from the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer when no external magnetic field is applied. The magnetic sensor according to claim 10.
The system comprises a plurality of the aforementioned magnetoresistive elements, The plurality of magnetoresistive elements are electrically connected to each other in at least one form, such as in series and in parallel. The magnetic sensor according to claim 10.
The magnetic sensor according to claim 10, It comprises a magnetic scale with at least one north pole and one south pole aligned, The positional change between the magnetic sensor and the magnetic scale is detected. Detector.
The magnetic sensor according to claim 10, It comprises a magnetic scale with at least one north pole and one south pole aligned, The speed of the positional change between the magnetic sensor and the magnetic scale is detected. Detector.
The magnetic sensor according to claim 10, It comprises a magnetic scale with at least one north pole and one south pole aligned, The acceleration of the change in position between the magnetic sensor and the magnetic scale is detected. Detector.

Description

This disclosure relates to magnetoresistive elements, magnetic sensors, and detectors. Magnetic sensors utilizing a TMR (Tunnel MagnetoResistance) structure are known. Patent Document 1 describes a magnetic sensor having two free layers made of magnetic material and a tunnel barrier layer as a TMR structure. In the TMR structure described in Patent Document 1, the magnetization directions of the two free layers are stably antiparallel to each other when no external magnetic field is applied. As the external magnetic field strength increases, the magnetization directions of the two free layers approach the direction of the external magnetic field. International Publication No. 2024/034206 Figure 1 is a cross-sectional view showing a magnetoresistive element according to Embodiment 1.Figure 2 is a top view showing a magnetoresistive element according to Embodiment 1.Figure 3 shows an example of the magnetization direction in a magnetic tunnel junction structure.Figure 4 is a diagram illustrating the change in resistance of a magnetoresistive element due to an external magnetic field.Figure 5 is a conceptual diagram showing the dependence of the strength of the exchange coupling energy due to the RKKY interaction on the thickness of the non-magnetic layer.Figure 6 is a cross-sectional view showing a modified magnetoresistive element according to Embodiment 1.Figure 7 is a perspective view showing a magnetic sensor according to Embodiment 2.Figure 8 is a perspective view showing a first example of a magnetic sensor according to a modified embodiment of the second embodiment.Figure 9 is a perspective view showing a second example of a magnetic sensor according to a modified embodiment of the second embodiment.Figure 10 is a perspective view showing a third example of a magnetic sensor according to a modification of Embodiment 2.Figure 11 is a perspective view showing a detector according to Embodiment 3.Figure 12 is a schematic diagram showing the stacked structure of the magnetic sensors in Examples 1 to 4.Figure 13 is a schematic diagram showing the stacked structure of the magnetic sensor in Comparative Example 1.Figure 14 shows the relationship between the exchange coupling energy due to the RKKY interaction and the thickness of the non-magnetic layer.Figure 15 shows the magnetoresistance characteristics of the magnetic sensors in Example 2 and Comparative Example 1.Figure 16 shows the maximum value of the resistance change rate of the magnetic sensor and the magnetic field strength representing the degree of the responsive magnetic field in Examples 1 to 4 and Comparative Example 1. (Summary of this disclosure) As an overview of this disclosure, examples of magnetoresistive elements, magnetic sensors, and detectors relating to this disclosure are shown below. For example, a magnetoresistive element according to a first aspect of this disclosure comprises a first magnetic layer, a second magnetic layer, and a third magnetic layer whose magnetization direction changes in response to an external magnetic field. The first magnetic layer comprises a first magnetic layer, a second magnetic layer, and a third magnetic layer stacked so as to be located between the second magnetic layer and the third magnetic layer; a first non-magnetic layer located between the first magnetic layer and the third magnetic layer; and a dielectric layer located between the first magnetic layer and the second magnetic layer. The first magnetic layer and the third magnetic layer are antiferromagnetically exchange-coupled via the first non-magnetic layer, and the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are stabilized in an antiparallel state when no external magnetic field is applied. As a result, the first magnetic layer and the third magnetic layer are antiferromagnetically coupled, causing the magnetization directions of the first magnetic layer and the third magnetic layer to rotate in a way that maintains this antiferromagnetic coupling. Consequently, the rotation of the magnetization direction of the first magnetic layer becomes gradual when the external magnetic field is increased. Therefore, in the magnetoresistive element according to this embodiment, a change in resistance can be obtained even when the magnitude of the external magnetic field changes in the region where the external magnetic field is large. Thus, the magnetoresistive element according to this embodiment can respond to a wide range of magnetic fields. Furthermore, for example, the magnetoresistive element according to the second aspect of this disclosure is the magnetoresistive element according to the first aspect, wherein the dielectric layer mainly comprises magnesium oxide, aluminum oxide, or magnesium-aluminum oxide. This allows for an improvement in the TMR characteristics of the magnetoresistive element. Furthermore, for example, a magnetoresistive element according to a third aspect