Perpendicular magnetic recording system with helical write coil and auxiliary coil for fast switching of write pole magnetization

• US 8,116,031 B2
• Filed: 04/06/2009
• Issued: 02/14/2012
• Est. Priority Date: 04/06/2009
• Status: Expired due to Fees

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Inventors: Alex, Michael, Contreras, John Thomas, Schabes, Manfred Ernst, Xing, Xinzhi
• Primary Examiner(s): Bernatz, Kevin
• Application Number:
  US12/419,278
• Publication Number:
  US 20100254041A1
• Time in Patent Office: 1,044 Days
• Field of Search: None
• US Class Current: 360/123.02
• CPC Class Codes: G11B 2005/001 Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
• CPC Class Codes: G11B 5/1278 specially adapted for magnetisations perpendicular to the surface of the record carrier
• CPC Class Codes: G11B 5/3123 by using special coil configurations or conductors

Abstract

A perpendicular magnetic recording system has a write head having a main helical coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The auxiliary coil is preferably a helical coil wrapped around the auxiliary pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Claims

1. A perpendicular magnetic recording write system for magnetizing regions in a perpendicular magnetic recording layer comprising:

a write head comprising

a main pole;

a main electrically conductive helical coil wrapped around the main pole for generating magnetic flux in the main pole;

an auxiliary pole oriented at an angle to the main pole greater than 15 degrees and less than or equal to 90 degrees; and

an auxiliary electrically conductive helical coil wrapped around the auxiliary pole;

a write driver capable of supplying write current in two directions to the main coil; and

circuitry coupled to the auxiliary coil for energizing the auxiliary coil when the write driver switches the direction of write current to the main coil.

2. The system of claim 1 wherein the auxiliary pole is oriented substantially orthogonal to the main pole.

3. The system of claim 1 wherein the auxiliary helical coil is a single-turn coil.

4. The system of claim 1 further comprising a flux guide connected to the auxiliary pole for directing magnetic flux from the auxiliary pole to the main pole.

5. The system of claim 1 wherein the main pole has a ferromagnetic resonance frequency and the circuitry coupled to the auxiliary coil energizes the auxiliary coil to generate an auxiliary magnetic field at said ferromagnetic resonance frequency.

6. The system of claim 1 wherein the write driver generates a primary signal at the write frequency, and wherein the circuitry coupled to the auxiliary coil comprises an oscillator for applying an auxiliary signal at a frequency greater than the write frequency.

7. The system of claim 6 wherein the write driver is coupled to the oscillator, and wherein the phase of the auxiliary signal from the oscillator is matched to the phase of the primary signal from the write driver.

8. The system of claim 1 wherein the write driver generates a primary signal, and wherein the circuitry coupled to the auxiliary coil comprises a high-pass filter for filtering from said primary signal a high-frequency component corresponding to the current-direction switching of the write current.

9. The system of claim 8 wherein the high-pass filter comprises two matched capacitors in series with the auxiliary coil, the auxiliary coil being located between the two capacitors.

10. The system of claim 1 wherein the write current from the write driver has a magnitude I_w and wherein the circuitry coupled to the auxiliary coil generates auxiliary current (I_a) having a magnitude greater than about 0.2I_w.

11. A magnetic recording disk drive perpendicular recording write head for magnetizing regions in data tracks of a perpendicular magnetic recording layer on the disk, the head being formed on a slider having an air-bearing surface (ABS) facing the recording layer and comprising:

a substrate;

a main pole on the substrate;

first and second return poles on the substrate and substantially coplanar with the main pole, the first and second return poles being spaced on opposite sides of the main pole in the cross-track direction and having ends substantially at the ABS, the first and second return poles being connected to the main pole at a region recessed from the ABS;

a write pole on and non-coplanar with the main pole and having an end substantially at the ABS;

a main electrically conductive helical coil wrapped around the main pole for generating magnetic flux in the main pole and its connected write pole;

an auxiliary pole oriented substantially orthogonal to the main pole; and

an auxiliary electrically conductive helical coil wrapped around the auxiliary pole.

12. The write head of claim 11 further comprising a flux guide connected to the auxiliary pole for directing magnetic flux from the auxiliary pole to the main pole.

13. The write head of claim 11 wherein the main helical coil comprises a first set of electrically conductive generally coplanar coil segments on the substrate and a second set of electrically conductive generally coplanar coil segments spaced from the first set of coil segments in the along-the-track direction, and wherein the main pole is located between the planes of said first and second sets of coil segments.

14. A magnetic recording disk drive perpendicular recording write system comprising:

the write head of claim 11;

a write driver capable of supplying write current in two directions to the main coil; and

circuitry coupled to the auxiliary coil for energizing the auxiliary coil when the write driver switches the direction of write current to the main coil.

15. The system of claim 14 wherein the write driver generates a primary signal at the write frequency, and wherein the circuitry coupled to the auxiliary coil comprises an oscillator for applying an auxiliary signal at a frequency greater than the write frequency.

16. The system of claim 15 wherein the write driver is coupled to the oscillator, and wherein the phase of the auxiliary signal from the oscillator is matched to the phase of the primary signal from the write driver.

17. The system of claim 14 wherein the write driver generates a primary signal, and wherein the circuitry coupled to the auxiliary coil comprises a high-pass filter for filtering from said primary signal a high-frequency component corresponding to the current-direction switching of the write current.

18. The system of claim 17 wherein the high-pass filter comprises two matched capacitors in series with the auxiliary coil, the auxiliary coil being located between the two capacitors.

19. The system of claim 14 wherein the write current from the write driver has a magnitude I_w and wherein the circuitry coupled to the auxiliary coil generates auxiliary current (I_a) having a magnitude greater than about 0.2I_w.

20. The system of claim 14 wherein the main pole has a ferromagnetic resonance frequency and wherein the circuitry coupled to the auxiliary coil energizes the auxiliary coil to generate an auxiliary magnetic field at said ferromagnetic resonance frequency.