Magnetic sensor

Patent metadata

Field	Value
Publication number	US-2020132786-A1
Application number	US-201916407234-A
Country	US
Kind code	A1
Filing date	May 9, 2019
Priority date	Oct 24, 2018
Publication date	Apr 30, 2020
Grant date	—

Abstract

17

First claim

What is claimed is:

1 . A magnetic sensor comprising:
a free layer whose magnetization direction changes in response to an external magnetic field; a pinned layer whose magnetization direction is fixed with respect to the external magnetic field; a spacer layer that is located between the pinned layer and the free layer and that exhibits a magnetoresistance effect; and at least one magnet film that is disposed on a lateral side of the free layer and that applies a bias magnetic field to the free layer, wherein a relationship of 0.7≤T C_HM /T C_FL ≤1.05 is satisfied, where T C_HM is Curie temperature of the magnet film, and T C_FL is Curie temperature of the free layer.

2 . The magnetic sensor according to claim 1 ,
wherein a relationship of 0.7≤T C_HM /T C_FL ≤0.9 is satisfied.

3 . A magnetic sensor comprising:
a free layer whose magnetization direction changes in response to an external magnetic field; a pinned layer whose magnetization direction is fixed with respect to the external magnetic field; a spacer layer that is located between the pinned layer and the free layer and that exhibits a magnetoresistance effect; and at least one magnet film that is disposed on a lateral side of the free layer and that applies a bias magnetic field to the free layer, wherein a relationship of 0.7≤T HK=0_HM /T C_FL ≤1.05 is satisfied, where T HK=0_HM is a temperature of the magnet film at which an anisotropic magnetic field thereof becomes zero, and T C_FL is Curie temperature of the free layer.

4 . A magnetic sensor comprising:
a free layer whose magnetization direction changes in response to an external magnetic field; a pinned layer whose magnetization direction is fixed with respect to the external magnetic field; a spacer layer that is located between the pinned layer and the free layer and that exhibits a magnetoresistance effect; and at least one magnet film that is disposed on a lateral side of the free layer and that applies a bias magnetic field to the free layer, wherein a relationship of 0.7≤T HC=0_HM /T C_FL ≤1.05 is satisfied, where T HC=0_HM is a temperature of the magnet film at which a coercive force thereof becomes zero, and T C_FL is a Curie temperature of the free layer.

5 . The magnetic sensor according to claim 1 , wherein the magnet film is mainly formed of CoPt, FePt or SmCo.

6 . The magnetic sensor according to claim 5 , wherein the magnet film further contains one or more elements selected from the group consisting of Cr, Ta, B, Ni, Ti, W, V, Mo, Mn, Zr, Nb, Hf, Si, Cu, Ag, Al, Ru and Rh.

7 . The magnetic sensor according to claim 3 , wherein the magnet film is mainly formed of CoPt, FePt or SmCo.

8 . The magnetic sensor according to claim 7 , wherein the magnet film further contains one or more elements selected from the group consisting of Cr, Ta, B, Ni, Ti, W, V, Mo, Mn, Zr, Nb, Hf, Si, Cu, Ag, Al, Ru and Rh.

9 . The magnetic sensor according to claim 4 , wherein the magnet film is mainly formed of CoPt, FePt or SmCo.

10 . The magnetic sensor according to claim 9 , wherein the magnet film further contains one or more elements selected from the group consisting of Cr, Ta, B, Ni, Ti, W, V, Mo, Mn, Zr, Nb, Hf, Si, Cu, Ag, Al, Ru and Rh.

11 . The magnetic sensor according to claim 1 , wherein an average grain diameter of magnetic grains that forms the magnetic film is 10 nm or more and 50 nm or less, as seen from a direction in which the free layer, the spacer layer and the outer pinned layer are stacked.

12 . The magnetic sensor according to claim 3 , wherein an average grain diameter of magnetic grains that forms the magnetic film is 10 nm or more and 50 nm or less, as seen from a direction in which the free layer, the spacer layer and the outer pinned layer are stacked.

13 . The magnetic sensor according to claim 4 , wherein an average grain diameter of magnetic grains that forms the magnetic film is 10 nm or more and 50 nm or less, as seen from a direction in which the free layer, the spacer layer and the outer pinned layer are stacked.

14 . The magnetic sensor according to claim 1 , wherein the at least one magnet film is a pair of magnet films that are located on both lateral sides of the free layer, and the free layer has a rectangular shape having short sides that face the pair of magnet films, as seen from a direction in which the free layer, the spacer layer and the pinned layer are stacked.

15 . The magnetic sensor according to claim 3 , wherein the at least one magnet film is a pair of magnet films that are located on both lateral sides of the free layer, and the free layer has a rectangular shape having short sides that face the pair of magnet films, as seen from a direction in which the free layer, the spacer layer and the pinned layer are stacked.

16 . The magnetic sensor according to claim 4 , wherein the at least one magnet film is a pair of magnet films that are located on both lateral sides of the free layer, and the free layer has a rectangular shape having short sides that face the pair of magnet films, as seen from a direction in which the free layer, the spacer layer and the pinned layer are stacked.

17 . The magnetic sensor according to claim 1 , wherein a ratio of a product of saturated magnetization and a film thickness of the magnet film to a product of saturated magnetization and a film thickness of the free layer is two or more and four or less.

18 . The magnetic sensor according to claim 3 , wherein a ratio of a product of saturated magnetization and a film thickness of the magnet film to a product of saturated magnetization and a film thickness of the free layer is two or more and four or less.

19 . The magnetic sensor according to claim 4 , wherein a ratio of a product of saturated magnetization and a film thickness of the magnet film to a product of saturated magnetization and a film thickness of the free layer is two or more and four or less.

Assignees

• Tdk Corp

Inventors

• Takano Kenichi
• Saito Yuta
• Hirabayashi Hiraku

Classifications

• H01F10/3272

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• B82Y25/00

  Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance · CPC title

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• H01F10/3295

  Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers · CPC title