MAGNETIC SENSOR USING SPIN TRANSFER TORQUE DEVICES

• US 20140139214A1
• Filed: 11/16/2012
• Published: 05/22/2014
• Est. Priority Date: 11/16/2012
• Status: Abandoned Application

• Current Assignee: Korea Basic Science Institute
• Original Assignee: Korea Basic Science Institute
• Inventors: Park, Seung Young, Kim, Sang II
• Application Number:
  US14/000,913
• Publication Number:
  US 20140139214A1
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: G01R 33/0064 comprising means for performing simulations, e.g. of the magnetic variable to be measured
• CPC Class Codes: G01R 33/1284 Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices G01R33/093 takes precedence; semiconductor devices using spin polarized carriers H01L29/66984

Abstract

The present invention is directed to a magnetic sensor using a spin transfer torque device, including a spin transfer torque device configured such that the magnetization direction thereof is varied by current, a bipolar pulse source configured to apply bipolar pulses to the spin transfer torque device in order to control the coercive field and sensitivity of the spin transfer torque device, and a signal processing unit configured to calculate magnetic susceptibility or magnetic resistance by counting the parallel (P) or anti-parallel (AP) states of the spin transfer torque device in response to the applied bipolar pulses.

Claims

1. A magnetic sensor using a spin transfer torque device, comprising:

a spin transfer torque device configured such that a magnetization direction thereof is varied by applied direct current (DC) power;

a bipolar pulse source configured to apply bipolar pulses to the spin transfer torque device in order to control a coercive field and sensitivity of the spin transfer torque devices;

a control unit configured to control a coercive field and sensitivity of the spin transfer torque device; and

a signal processing unit configured to calculate magnetic susceptibility or magnetic resistance by counting parallel (P) or anti-parallel (AP) states of the spin transfer torque device in response to the applied bipolar pulses.

2. The magnetic sensor of claim 1, wherein the signal processing unit comprises:

a counter configured to count the P or AP states of the spin transfer torque device; and

a computation unit configured to perform computation on values counted by the counter.

3. The magnetic sensor of claim 1, wherein a low frequency band-pass filter is added upstream of the signal processing unit in order to eliminate high frequency components attributable to the bipolar pulses.

4. The magnetic sensor of claim 1, further comprising a bias unit configured to apply an offset bias to the spin transfer torque device in order to control a location of a dynamic range of the spin transfer torque device.

5. The magnetic sensor of claim 1, further comprising a resistor unit of a resistance characteristic connected in series to the spin transfer torque device, wherein an output level of the magnetic sensor is adjusted by controlling a resistance value of the resistor unit.

6. The magnetic sensor of claim 5, wherein the output level of the magnetic sensor is adjusted by a second spin transfer torque device connected in series to the spin transfer torque device.

7. A magnetic sensor using a spin transfer torque device, comprising:

a spin transfer torque device configured such that a magnetization direction thereof is varied by applied DC power;

a bipolar pulse source configured to apply bipolar pulses to the spin transfer torque device in order to control a coercive field and sensitivity of the spin transfer torque device; and

a low frequency band-pass filter configured to extract an average value of fluctuating magnetic resistance of the spin transfer torque device.

8. An integrated circuit chip of a spin transfer torque-type magnetic sensor, comprising:

a spin transfer torque device configured such that a magnetization direction thereof is varied by applied DC power;

an offset control unit configured to control an offset of output of the spin transfer torque device; and

electrode pads configured to receive and output signals from and to the spin transfer torque device;

wherein the spin transfer torque device, the offset control unit, and the electrode pads are integrated into a single substrate.

9. The integrated circuit chip of a spin transfer torque-type magnetic sensor of claim 8, further comprising:

a coercive field/dynamic range control unit configured to control a coercive field and sensitivity of the spin transfer torque device; and

a signal processing unit configured to calculate magnetic susceptibility or magnetic resistance by counting P or AP states of the spin transfer torque device in response to the applied bipolar pulses.

10. The integrated circuit chip of a spin transfer torque-type magnetic sensor of claim 9, comprising a low frequency band-pass filter configured to extract an average of the magnetic susceptibility of the spin transfer torque device, instead of the signal processing unit.

11. The integrated circuit chip of a spin transfer torque-type magnetic sensor of claim 8, further comprising an analog-to-digital converter (ADC) configured to convert analog signals of the sensor into digital signals.

12. A disposable magnetic sensor using a spin transfer torque device, wherein the disposable magnetic sensor uses the integrated circuit chip of claim 8.

13. A method, comprising connecting the disposable magnetic sensor of claim 12 to a port of a mobile communication terminal, running a magnetic field measurement application of the mobile communication terminal, and measuring a magnetic field applied to the magnetic sensor.

14. A nondestructive test sensor for detecting micro-cracks, wherein the nondestructive test sensor uses the integrated circuit chip of a spin transfer torque-type magnetic sensor of claim 8.

15. A medical nanoparticle sensor, wherein the medical nanoparticle sensor uses the integrated circuit chip of a spin transfer torque-type magnetic sensor of claim 8.