Stress sensor and manufacturing method therefor
AssigneesMurata Manufacturing Co., Ltd., The University of Tokyo
InventorsAkira Ando, Daichi Chiba
Life of this patent
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Abstract
Disclosed herein is a stress sensor that includes a stress detection layer including a laminated body including a first ferromagnetic layer, a first non-magnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer stacked one on another. The antiferromagnetic layer includes Mn, and the magnetization direction of the second ferromagnetic layer is fixed by the exchange bias caused by the exchange coupling with the antiferromagnetic layer. The stress sensor detects a stress by an electric resistance depending upon a relative angle between magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, the relative angle changing depending upon an externally applied stress.
Claims19
A stress sensor comprising:
- a stress detection layer including a laminated body including a first ferromagnetic layer, a first non-magnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer stacked one on another, wherein:
- the antiferromagnetic layer includes Mn,
- a magnetization direction of the second ferromagnetic layer is fixed by an exchange bias caused by an exchange coupling with the antiferromagnetic layer, and
- the stress sensor detects a stress by an electric resistance depending upon a relative angle between magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, the relative angle changing depending upon an externally applied stress,
- wherein the electric resistance is detected by a magnitude of a detection current flowing into all layers of the stress detection layer.
A stress sensor comprising:
- a stress detection layer including a laminated body including a first ferromagnetic layer, a first non-magnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer stacked one on another, wherein:
- the antiferromagnetic layer includes Mn,
- a magnetization direction of the second ferromagnetic layer is fixed by an exchange bias caused by an exchange coupling with the antiferromagnetic layer, and
- the stress sensor detects a stress by an electric resistance depending upon a relative angle between magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, the relative angle changing depending upon an externally applied stress, wherein:
- the stress detection layer further includes a third ferromagnetic layer, a second non-magnetic layer, and a fourth ferromagnetic layer, in addition to the laminated body, and
- a magnetization direction of the third ferromagnetic layer is fixed by an exchange bias caused by an exchange coupling with the antiferromagnetic layer.
A method for manufacturing a stress sensor, the method comprising:
- performing annealing of at least a second ferromagnetic layer and an antiferromagnetic layer of the stress sensor in a magnetic field, wherein the performing of the annealing in the magnetic field comprises:
- heat treating the second ferromagnetic layer and the antiferromagnetic layer in the magnetic field,
- cooling the second ferromagnetic layer and the antiferromagnetic layer to room temperature in the magnetic field,
- forming an exchange coupling between the second ferromagnetic layer and the antiferromagnetic layer, and
- fixing a magnetization direction of the second ferromagnetic layer by an exchange bias caused by the exchange coupling, and
- wherein the stress sensor detects a stress by an electric resistance depending upon a relative angle between magnetization directions of a first ferromagnetic layer and the second ferromagnetic layer, the relative angle changing depending upon an externally applied stress.
Dependencies are inferred from the claim text.