MAGNETIC SENSOR

• US 20180252780A1
• Filed: 08/31/2017
• Published: 09/06/2018
• Est. Priority Date: 03/03/2017
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: IWASAKI, Hitoshi, KIKITSU, Akira, SHIROTORI, Satoshi, TAKAGISHI, Masayuki
• Application Number:
  US15/693,272
• Publication Number:
  US 20180252780A1
• Time in Patent Office: Days
• CPC Class Codes: G01R 33/091 Constructional adaptation of the sensor to specific applications
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00

Abstract

In one embodiment, a magnetic sensor has first and second electrode, a magneto-resistive effect element, an insulating layer between the first electrode and the element, a current source portion and a detecting portion. The element has a length in a first direction along a film surface of the element which is larger than that in a second direction along the film surface and perpendicular to the first direction. The element includes first, non-magnetic and second magnetic layers. The magnetization direction of the first magnetic layer is along the first direction. The element is connected to the first and second electrodes. The current source portion is connected to the first and second electrodes. The detecting portion can detect a second harmonic component in an output signal of the element. The first electrode and the element overlap each other in a third direction perpendicular to the first and the second directions.

Claims

1. a first electrode;

a second electrode which is provided apart from the first electrode;

a magneto-resistive effect element having a length in a first direction along a film surface of the magneto-resistive effect element which is larger than a length in a second direction along the film surface and perpendicular to the first direction, the magneto-resistive effect element including a first magnetic layer, a non-magnetic layer and a second magnetic layer, the magnetization direction of the first magnetic layer being along the first direction, further the magneto-resistive effect element being connected electrically to the first electrode and the second electrode;

an insulating layer provided between the first electrode and the magneto-resistive effect element;

a current source-portion which is connected to the first electrode and the second electrode and for supplying an alternating current to the magneto-resistive effect element;

a detecting portion which can detect a second harmonic component in an output signal of the magneto -resistive effect element, wherein

the first electrode and the magneto-resistive effect element overlap each other in a third direction perpendicular to the first and the second directions so as to extend along each other.

2. The magnetic sensor according to claim 1, wherein the first electrode and the second electrode are arranged to intersect each other.

3. The magnetic sensor according to claim 1, wherein the non-magnetic layer contains MgO.

4. The magnetic sensor according to claim 1, wherein the length the magneto-resistive effect element in the first direction is 10 or more times larger than that in the second direction.

5. The magnetic sensor according to claim 1, further comprising a bandpass filter, wherein the bandpass filter receives an output signal from the magneto-resistive effect element and restricts the output signal to a signal component in the vicinity of a frequency twice the frequency of the alternating current to output to the detecting portion.

6. The magnetic sensor according to claim 1, wherein the current source portion can further supply a direct current which has a current value smaller than that of the alternating current.

7. The magnetic sensor according to claim 1, further comprising a reference magneto-resistive effect element, wherein a difference between an output which is obtained by flowing current in the reference magneto-resistive effect element and another output which is obtained by flowing current in the magneto-resistive effect element which overlaps the first electrode is detected.

8. The magnetic sensor according to claim 1, further comprising a third electrode and another magneto-resistive effect element which has a length in the second direction larger than a length in the first direction, wherein

the second electrode and the other magneto-resistive effect element overlap each other in a third direction so as to extend along each other, and a current is flowed in the other magneto-resistive effect element with the third electrode and the second electrode.

9. The magnetic sensor according to claim 8, wherein the first electrode and the second electrode are arranged to intersect each other, and the third electrode and the second electrode are arranged to intersect each other.

10. The magnetic sensor according to claim 8, wherein the magnetic sensor includes a plurality of first electrodes, a plurality of second electrodes arranged to intersect the first electrodes, a plurality of magneto-resistive effect elements overlapping the first electrode and a plurality of other magneto-resistive effect elements overlapping the second electrode, and the magneto-resistive effect elements overlapping the first electrodes are arranged along the first electrodes and the other magneto-resistive effect elements overlapping the second electrodes are arranged along the second electrodes so that the magneto-resistive effect elements and the other magneto-resistive effect elements are disposed in a shape of lattice.

11. The magnetic sensor according to claim 1, further comprising another insulating layer provided on the magneto-resistive effect element, wherein a cell of a living body can be arranged on the other insulating layer.

12. The magnetic sensor according to claim 2, wherein the first electrode extends in the first direction, and the second electrode extends in the second direction.

13. The magnetic sensor according to claim 10 wherein the first electrode and the third electrode extend in the first direction, and the second electrode extends in the second direction.

14. The magnetic sensor according to claim 1, wherein one of the first magnetic layer and the second magnetic layer is divided into two portions across an insulation part on the non-magnetic layer

15. The magnetic sensor according to claim 10, wherein a plurality of third electrodes are alternately arranged among the first electrodes with a different distance between neighbored electrodes.

16. The magnetic sensor according to claim 14, wherein an underlayer with lower resistivity than the first and second magnetic layers is arranged under the first and second magnetic layers.