Magnetic Sensor

• US 20110175605A1
• Filed: 10/27/2010
• Published: 07/21/2011
• Est. Priority Date: 01/21/2010
• Status: Active Grant

• Current Assignee: The Industry & Academic Cooperation In Chungnam National University
• Original Assignee: The Industry & Academic Cooperation In Chungnam National University
• Inventors: Kim, Dong Young, Tran, Quang Hung, Jeong, Jong-Ryul, Kim, CheolGi
• Granted Patent: US 9,519,036 B2
• Time in Patent Office: Days
• US Class Current: 324/251
• CPC Class Codes: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01R 33/09 Magnetoresistive devices

Abstract

Provided is a magnetic sensor for detecting a magnetic field. The magnetic sensor includes a magnetic layer of a closed loop shape; a pair of current terminals which face each other contacting with the closed loop and through which current is input/output; and a pair of voltage terminals which face each other contacting with the closed loop and from which output voltage is detected. Both an anisotropic magnetoresistance effect (AME) and a planar Hall effect (PHE) contribute to the output voltage and a hysteresis of the output voltage is eliminated by exchange coupling of a ferromagnetic layer by a ferromagnetic-antiferromagnetic layer structure and a ferromagnetic-metal-antiferromagnetic layer structure. Accordingly, it is possible to minimize a hysteresis due to a demagnetization factor of the closed loop, stabilize the output voltage of the magnetic sensor and enhance sensitivity.

Claims

1. A magnetic sensor, comprising:

a magnetic layer of a closed loop shape;

a pair of current terminals which face each other contacting with the closed loop and through which current is input/output; and

a pair of voltage terminals which face each other contacting with the closed loop and from which output voltage is detected.

2. The magnetic sensor of claim 1, wherein the output voltage from the pair of voltage terminals has a characteristic of anisotropic magnetoresistance effect (AME) and planar Hall effect (PHE) of the magnetic layer.

3. The magnetic sensor of claim 2, wherein the closed loop is a circular closed loop, an oval closed loop or a polygonal closed loop.

4. The magnetic sensor of claim 3, wherein the closed loop is a circular closed loop and a ratio of voltages generated by the anisotropic magnetoresistance effect and by the planar Hall effect which contribute to the output voltage is adjusted by a ratio (R/W ratio) of a radius (R) of the closed loop and a width (W) of the closed loop.

5. The magnetic sensor of claim 4, wherein the R/W ratio of radius of the closed loop and the width of the closed loop is 0.5 or larger.

6. The magnetic sensor of claim 1, wherein a terminal selected from the pair of current terminals and a terminal selected from the pair of voltage terminals have a symmetric structure of 90°

angle.

7. The magnetic sensor of claim 1, wherein input current through the terminal selected from the pair of current terminals is direct current (DC), alternating current (AC) or a pulse.

8. The magnetic sensor of claim 2, wherein the magnetic layer includes a ferromagnetic film combined with exchange coupling.

9. The magnetic sensor of claim 8, wherein the magnetic layer includes a ferromagnetic film and is more than one film selected from the group consisting of an antiferromagnetic film, an insulator film and a non-magnetic metal film for a multilayered structure with the ferromagnetic films.

10. The magnetic sensor of claim 9, wherein the magnetic layer is a multilayered structure including a ferromagnet antiferromagnet films;

a multilayered structure including a ferromagnet-metal-antiferromagnet films;

a multilayered structure including a ferromagnet I-insulator or metal-ferromagnet II-antiferromagnet films.

11. The magnetic sensor of claim 1, which further forms a second magnetic layer, which is made of the same material as the magnetic layer of the closed loop, is concentric with the closed loop and is separated to a predetermined distance from the closed loop inside the closed loop.

12. The magnetic sensor of claim 11, which further forms a third magnetic layer that is made of the same material as the magnetic layer of the closed loop and is separated to a predetermined distance from the closed loop, each of the current terminals and each of the voltage terminals outside the closed loop closed loop.

13. The magnetic sensor of claim 2, which is a magnetic field sensor, a bio-sensor, a permeability sensor, an eddy current sensor for non-destructive inspection, a magnetic field imaging sensor, a nuclear magnetic resonance (NMR) sensor, 3-axis magnetic field sensor or compass sensor.

14. The magnetic sensor of claim 1, wherein input current through the terminal selected from the pair of current terminals is controlled by current mode or voltage mode depending on the R/W ratio.

15. The magnetic sensor of claim 2, wherein more than two units selected from the group consisting of the magnetic layer;

the pair of current terminals; and

the pair of voltage terminals as one unit are arrayed.