Absolute track width measurement on magnetic recording heads
AssigneeInternational Business Machines Corporation
InventorMichael Diederich
Life of this patent
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Abstract
A method for magnetically measuring the magnetic read width (MRW) of magnetic recording heads having a track width that is equal or smaller than the wavelength of visible light is provided. The heads comprise a magnetic read head spin valve sensor and the magnetic read head sensor signal is used to derive an unknown track width from comparing to the sensor response of a known track width. Using this method, track widths in the regions at the wavelength of light and below (<500 nm) can be directly measured without destroying the respective sensor material.
Claims8
An apparatus for magnetically measuring a magnetic read width of magnetic recording heads having a track width that is equal to or smaller than a wavelength of visible light, the heads having a magnetic read head spin valve sensor, the apparatus comprising:
- means for measuring a resistance change of a sensor film for a known track width by sweeping a magnetic field in an axis of a spin valve pinning;
- means for measuring the resistance change of the sensor film for an unknown track width by sweeping a magnetic field in the axis of the spin valve pinning;
- and
- means for calculating the unknown track width by comparing the resistance changes.
A method of magnetically measuring the magnetic read width of magnetic recording heads having a track width that is equal to or smaller than a wavelength of visible light, the heads comprising a magnetic read head spin valve sensor, the method comprising the steps of:
- a) measuring a resistance change of a sensor film for a known track width by sweeping a magnetic field in an axis of the spin valve pinning;
- b) measuring the resistance change of the sensor film for an unknown track width by sweeping a magnetic field in the axis of the spin valve pinning;
- and
- c) calculating the unknown track width by comparing the resistance changes.
A computer program product stored on a computer usable medium having computer readable program code means, the program comprising:
- means for measuring a resistance change of a sensor film for a known track width by sweeping a magnetic field in an axis of the spin valve pinning;
- means for measuring the resistance change of the sensor film for an unknown track width by sweeping a magnetic field in the axis of the spin valve pinning;
- and
- means for calculating the unknown track width by comparing the resistance changes.
Dependencies are inferred from the claim text.