Switching period control of microwave assisted magnetic recording for pole erasure suppression

Patent metadata

Field	Value
Publication number	US-10283159-B2
Application number	US-201816003413-A
Country	US
Kind code	B2
Filing date	Jun 8, 2018
Priority date	Nov 24, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A magnetic recording system for preventing data loss resulting magnetic oscillator current. The magnetic recording system includes a magnetic write head with a magnetic write pole, a magnetic oscillator near the magnetic write pole, and a write coil for magnetizing the write pole. Circuitry is connected with the magnetic write coil to supply a current to the write coil and connected with the magnetic oscillator to supply a current to the magnetic oscillator. The circuitry is configured to ensure that the current to the magnetic oscillator does not inadvertently magnetize the write pole after the magnetic write pole has demagnetized.

First claim

What is claimed is:

1. A magnetic write head comprising:
a magnetic write pole;
a magnetic oscillator adjacent to the magnetic write pole to generate an oscillating magnetic field; and
circuitry connected to the magnetic oscillator, wherein the circuity is configured to flow current through the magnetic oscillator such that the magnetic write pole completes demagnetization upon termination of writing after the current through the magnetic oscillator has decayed.

2. The magnetic write head of claim 1 , wherein the circuitry is further configured to reduce a fall time of the current through the magnetic oscillator to fall to zero without changing a length of time for the magnetic write pole to complete demagnetization.

3. The magnetic write head of claim 1 , wherein the circuitry is further configured to increase a length of time for the demagnetization of the magnetic write pole to complete such that the demagnetization is completed after the current through the magnetic oscillator has decayed.

4. The magnetic write head of claim 3 , wherein the circuitry is further configured to apply a direct current to the magnetic write pole for a predetermined period to increase the length of time.

5. The magnetic write head of claim 1 , wherein the magnetic oscillator is a spin torque oscillator.

6. The magnetic write head of claim 1 , wherein the magnetic oscillator comprises a spin injection layer, a magnetic oscillation layer, and a non-magnetic spacer layer sandwiched between the spin injection layer and the magnetic oscillation layer.

7. The magnetic write head of claim 1 , wherein the magnetic oscillator is positioned between the magnetic write pole and a trailing magnetic shield of the write head.

8. A magnetic recording system comprising:
a magnetic write pole;
a magnetic oscillator adjacent to the magnetic write pole, wherein the magnetic oscillator is configured to generate an oscillating magnetic field; and
circuitry connected to the magnetic oscillator configured to induce a magnetic oscillator current through the magnetic oscillator, wherein the circuitry is further configured to reduce a fall time of the magnetic oscillator current to zero before the magnetic write pole has completely demagnetized upon termination of writing.

9. The magnetic recording system of claim 8 , wherein the circuitry comprises a capacitor and a first resistor connected in parallel between an input and an output.

10. The magnetic recording system of claim 9 , wherein the fall time of the magnetic oscillator current is adjusted by adjusting a resistance value of the first resistor.

11. The magnetic recording system of claim 10 , wherein the fall time of the magnetic oscillator current is reduced by decreasing the resistance value of the first resistor.

12. The magnetic recording system of claim 9 , further comprising a second resistor connected to the input and in series with the capacitor and the first resistor.

13. The magnetic recording system of claim 12 , wherein a first switch is connected in series with the first resistor to selectively control flow of current through the first resistor, and wherein a second switch is connected in series with the second resistor to control the flow of current through the second resistor.

14. The magnetic recording system of claim 8 , wherein the magnetic oscillator comprises a spin injection layer, a magnetic oscillation layer, and a non-magnetic spacer layer sandwiched between the spin injection layer and the magnetic oscillation layer, wherein the spin injection layer has a fixed magnetization, and wherein the magnetic oscillation layer has an oscillating magnetization.

15. The magnetic recording system of claim 8 , wherein the magnetic oscillator is positioned between the magnetic write pole and a trailing magnetic shield of a write head.

Assignees

• Western Digital Tech Inc

Inventors

• Tabata Satoshi
• Yamada Atsushi
• Kazusawa Michiya
• Shiimoto Masato

Classifications

• G11B2005/0024

  Microwave assisted recording · CPC title

• G11B5/3153

  including at least one magnetic thin film coupled by interfacing to the basic magnetic thin film structure · CPC title

• G11B5/40

  Protective measures on heads, e.g. against excessive temperature  (G11B5/31 takes precedence; protection against wear G11B5/255  {; protective structure of the head: see under structures, e.g. G11B5/3106}) · CPC title

• G11B5/02 Primary

  Recording, reproducing, or erasing methods; Read, write or erase circuits therefor · CPC title

• G11B20/10009 Primary

  Improvement or modification of read or write signals · CPC title