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

Patent metadata

Field	Value
Publication number	US-10020020-B2
Application number	US-201715788173-A
Country	US
Kind code	B2
Filing date	Oct 19, 2017
Priority date	Nov 24, 2015
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

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 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 to induce a direct current through the magnetic oscillator during operation of the magnetic oscillator and an alternating current through the magnetic oscillator for a predetermined period upon deactivation of the magnetic oscillator.

2. The magnetic recording system of claim 1 , wherein the circuitry comprises:
a first transistor and second transistor connected to a first input; and
a third transistor and fourth transistor connected to a second input;
wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are selectively activated and deactivated by a control signal to output either the direct current or the alternating current.

3. The magnetic recording system of claim 2 , wherein the control signal comprises a first control signal connected to the first transistor and the fourth transistor and a second control signal connected to the second transistor and the third transistor.

4. The magnetic recording system of claim 3 , wherein the first control signal is connected to a base terminal of the first transistor and a base terminal of the fourth transistor, and the second control signal is connected to a base terminal of the second transistor and a base terminal of the third transistor.

5. The magnetic recording system of claim 4 , wherein each of the first transistor, the second transistor, the third transistor, and the fourth transistor is an NPN transistor, wherein a collector terminal of the first transistor and a collector terminal of the second transistor are connected to the first input, wherein an emitter terminal of the third transistor and an emitter terminal of the fourth transistor are connected to the second input, and wherein an emitter terminal of the first transistor is connected to a collector terminal of the third transistor and an emitter terminal of the second transistor is connected to a collector terminal of the fourth transistor.

6. The magnetic recording system 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, wherein the spin injection layer has a fixed magnetization, and wherein the magnetic oscillation layer has an oscillating magnetization.

7. The magnetic recording system of claim 1 , further comprising a magnetic media adjacent to the magnetic write pole, wherein the magnetic media comprises a magnetic top layer, and wherein a magnetic anisotropy of the magnetic top layer is lowered upon excitation by the oscillating magnetic field to facilitate writing on the magnetic media.

8. The magnetic recording system of claim 1 , wherein the magnetic oscillator is between the magnetic write pole and a trailing shield of a magnetic write head.

9. The magnetic recording system of claim 1 , wherein the alternating current is a damping alternating current.

Assignees

• Western Digital Tech Inc

Inventors

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

Classifications

• G11B5/3153

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

• G11B5/235

  Selection of material for gap filler {(G11B5/232 takes precedence)} · CPC title

• G11B2005/0024

  Microwave assisted recording · CPC title

• G11B5/1278

  specially adapted for magnetisations perpendicular to the surface of the record carrier · CPC title

• G11B20/10009 Primary

  Improvement or modification of read or write signals · CPC title