Magnetic-recording head with touch-down detector incorporating a carbon nano-tube
A magnetic-recording head with touch-down detector incorporating a carbon nano-tube (CNT). The magnetic-recording head includes a write element, a read element and a touch-down detector. The write element is configured to write data to a magnetic-recording disk. The read element is configured to read data from the magnetic-recording disk. The touch-down detector includes a thermal sensor, and a CNT portion. The thermal sensor is configured to convert heat to a voltage signal. The CNT portion is configured to touch down on the magnetic-recording disk. The CNT portion is also coupled to the thermal sensor, and is configured to transfer heat generated by contact between the CNT portion and the magnetic-recording disk to the thermal sensor. A hard-disk drive (HDD) including the magnetic-recording head with touch-down detector incorporating a CNT, and a method for detecting contact between the magnetic-recording head and a recording surface of a magnetic-recording disk are also provided.
1. A magnetic-recording head with touch-down detector incorporating a carbon nano-tube, said magnetic-recording head comprising: a write element configured to write data to a magnetic-recording disk; a read element configured to read data from said magnetic-recording disk; an overcoat layer disposed on a disk-facing side of said magnetic-recording head, a disk-facing side of said overcoat layer defining a portion of an air-bearing surface, and said overcoat layer having an aperture through which a carbon-nano-tube portion is configured to extend towards a surface of a magnetic-recording disk, and a touch-down detector comprising: a thermal sensor configured to convert heat to a voltage signal; and said carbon-nano-tube portion configured to touch down on said magnetic-recording disk, said carbon-nano-tube portion coupled to said thermal sensor, and configured to transfer heat generated by contact between said carbon-nano-tube portion and said magnetic-recording disk to said thermal sensor.
2. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion is disposed at an air-bearing surface of said magnetic-recording head.
3. The magnetic-recording head of claim 2 , wherein said thermal sensor is disposed on a side of said magnetic-recording head opposite to a side of said magnetic-recording head where said air-bearing surface is disposed.
4. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion comprises at least one carbon nano-tube, said carbon nano-tube having a diameter less than about one nanometer (nm).
5. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion comprises a single-wall carbon nano-tube, said single-wall carbon nano-tube oriented with its tube axis about perpendicular to an air-bearing surface of said magnetic-recording head.
6. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion comprises a plurality of single-wall carbon nano-tubes, said plurality of single-wall carbon nano-tubes arranged in a bundle and oriented with their tube axes about parallel to one another and perpendicular to an air-bearing surface of said magnetic-recording head.
7. The magnetic-recording head of claim 6 , wherein said bundle of said plurality of single-wall carbon nano-tubes subtends a total area at said air-bearing surface less than about ten square nanometers (nm 2 ).
8. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion is aligned along a vertical direction to an air-bearing surface.
9. The magnetic-recording head of claim 1 , wherein said thermal sensor comprises a thermocouple.
10. The magnetic-recording head of claim 9 , wherein said thermocouple comprises a bimetallic structure, said bimetallic structure sufficiently sensitive to generate a voltage in response to heat transferred from said carbon-nano-tube portion to said thermal sensor.
11. The magnetic-recording head of claim 1 , wherein said thermal sensor comprises a resistor.
12. The magnetic-recording head of claim 11 , wherein said resistor comprises a single layer of resistive material, said resistive material having a thermal coefficient of resistance sufficiently sensitive to change the resistance of said resistor in response to heat transferred from said carbon-nano-tube portion to said thermal sensor.
13. The magnetic-recording head of claim 1 , wherein said carbon-nano-tube portion has a vertical dimension greater than or equal to an overcoat layer disposed on an air-bearing-surface side of said magnetic-recording head.
14. A hard-disk drive having a magnetic-recording head with touch-down detector incorporating a carbon nano-tube, said hard-disk drive comprising:
a disk enclosure;
a spindle motor mounted in a disk-enclosure base of said disk enclosure;
a spindle coupled to said spindle motor;
at least one magnetic-recording disk rotatably mounted on said spindle; and
at least one a magnetic-recording head comprising:
a write element configured to write data to a magnetic-recording disk;
a read element configured to read data from said magnetic-recording disk; and
a touch-down detector comprising:
a thermal sensor configured to convert heat to a voltage signal; and
a carbon-nano-tube portion configured to touch down on said magnetic-recording disk, said carbon-nano-tube portion coupled to said thermal sensor, and configured to transfer heat generated by contact between said carbon-nano-tube portion and said magnetic-recording disk to said thermal sensor, wherein said carbon-nano-tube portion as a vertical dimension greater than or equal to an overcoat layer disposed on an air-bearing-surface side of said magnetic-recording head.
15. The hard-disk drive of claim 14 , wherein said carbon-nano-tube portion is disposed at an air-bearing surface of said magnetic-recording head.
16. The hard-disk drive of claim 15 , wherein said thermal sensor is disposed on a side of said magnetic-recording head opposite to a side of said magnetic-recording head where said air-bearing surface is disposed.
17. The hard-disk drive of claim 14 , wherein said carbon-nano-tube portion comprises at least one carbon nano-tube.
18. The hard-disk drive of claim 14 , wherein said carbon-nano-tube portion is aligned along a vertical direction to an air-bearing surface.
19. The hard-disk drive of claim 14 , wherein said thermal sensor comprises a thermocouple.
20. The hard-disk drive of claim 19 , wherein said thermocouple comprises a bimetallic structure, said bimetallic structure sufficiently sensitive to generate a voltage in response to heat transferred from said carbon-nano-tube portion to said thermal sensor.
21. The hard-disk drive of claim 14 , wherein thermal sensor comprises a resistor.
22. The hard-disk drive of claim 21 , wherein said resistor comprises a single layer of resistive material, said resistive material having a thermal coefficient of resistance sufficiently sensitive to change the resistance of said resistor in response to heat transferred from said carbon-nano-tube portion to said thermal sensor.