Magnetization control for magnetic shield in magnetic recording head
A hard disk drive (HDD) is described which includes a magnetic field-generating device in the vicinity of a load/unload ramp such that the write head moves into a magnetic field generated by the device while the head is being unloaded from disk, whereby the magnetic field pins in a predominant direction the direction of magnetization of a magnetic shield associated with the write head, and away from the direction toward the disk. Recording magnetic field leakage associated with the shield is thereby suppressed and corresponding far track interference is inhibited.
1. A hard disk drive comprising:
a magnetic-recording disk rotatably mounted on a spindle;
a magnetic recording head comprising:
a magnetic write pole extending to an air bearing surface,
a write head magnetic shield disposed in the vicinity of said magnetic write pole, said magnetic shield having a predominant direction of magnetization;
at least one magnetic return pole, magnetically connected with said write pole in a region removed from said air bearing surface;
a load/unload ramp positioned for unloading said magnetic recording head from said magnetic recording disk; and
a magnetic field-generating device positioned in the vicinity of said load/unload ramp such that said magnetic recording head moves into a magnetic field generated by said magnetic field-generating device while said magnetic recording head is unloaded, said magnetic field pinning the direction of magnetization of said magnetic shield in said predominant direction of magnetization.
2. The hard disk drive of claim 1 , wherein said magnetic field-generating device is a permanent magnet.
3. The hard disk drive of claim 1 , wherein said magnetic field-generating device is an electromagnet.
4. The hard disk drive of claim 1 , wherein said magnetic field-generating device is an alternating-current-based magnetic field-generating device.
5. The hard disk drive of claim 1 , wherein said magnetic shield is positioned on a trailing side of said magnetic write pole.
6. The hard disk drive of claim 1 , wherein said predominant direction of magnetization of said magnetic shield is in a cross-track direction relative to said magnetic recording disk.
7. The hard disk drive of claim 1 , wherein said load/unload ramp comprises said magnetic field-generating device.
8. The hard disk drive of claim 1 , wherein said magnetic field-generating device is positioned adjacent to said load/unload ramp.
9. A method for managing far track interference (FTI), the method comprising:
unloading a magnetic recording head from a magnetic recording medium to an unloaded position;
while unloading to said unloaded position, moving said magnetic recording head into a magnetic field generated by a magnetic field-generating device, said magnetic field pinning in a predominant direction the direction of magnetization of a write head magnetic shield associated with said magnetic recording head.
10. The method of claim 9 , further comprising:
said magnetic recording head recording data to a desired track of said magnetic recording medium, such that data recorded on recording tracks more than one track away from said desired recording track are not affected by recording magnetic field leakage associated with said magnetic shield had said direction of magnetization of said magnetic shield not been pinned by said magnetic field generated by said magnetic field-generating device.
11. The method of claim 9 , further comprising:
tracking a count of a number of write operations performed by said magnetic recording head on a particular unit of storage; and
wherein unloading said magnetic recording head includes unloading said magnetic recording head in response to said count exceeding a certain number.
12. The method of claim 11 , wherein said particular unit of storage is a track sector.
13. The method of claim 9 , wherein said magnetic recording head is a heat-assisted magnetic recording (HAMR) head, the method further comprising:
tracking a count of a number of heat interactions with said magnetic recording medium performed by said HAMR head; and
wherein unloading said magnetic recording head includes unloading said HAMR head in response to said count exceeding a certain number.
14. The method of claim 9 , wherein moving said magnetic recording head includes moving said magnetic recording head into said magnetic field generated by a permanent magnet.
15. The method of claim 9 , wherein moving said magnetic recording head includes moving said magnetic recording head into said magnetic field generated by an electromagnet.
16. The method of claim 9 , wherein moving said magnetic recording head includes moving said magnetic recording head into said magnetic field generated by an alternating current-based magnetic field-generating device.
17. The method of claim 9 , wherein pinning includes pinning in said predominant direction said direction of magnetization of said magnetic shield positioned on a trailing side of a magnetic write pole of said magnetic recording head.
18. The method of claim 9 , wherein pinning includes pinning said direction of magnetization of said magnetic shield in a cross-track direction relative to said magnetic recording medium.
19. The method of claim 9 , wherein moving said magnetic recording head includes moving said magnetic recording head into said magnetic field generated by said magnetic field-generating device that is constituent to a load/unload ramp.