초록 ▼

A cap layer structure includes first and second cap layers wherein the first cap layer is composed of a nonmagnetic metal and the second cap layer is composed of iron oxide. Both cap layers are specular reflectors which reflect conduction electrons back into a spin scattering region of a spin valve

A cap layer structure includes first and second cap layers wherein the first cap layer is composed of a nonmagnetic metal and the second cap layer is composed of iron oxide. Both cap layers are specular reflectors which reflect conduction electrons back into a spin scattering region of a spin valve sensor without increasing the uniaxial anisotropy HKof a free layer structure within the spin valve sensor.

대표청구항 ▼

A cap layer structure includes first and second cap layers wherein the first cap layer is composed of a nonmagnetic metal and the second cap layer is composed of iron oxide. Both cap layers are specular reflectors which reflect conduction electrons back into a spin scattering region of a spin valve

A cap layer structure includes first and second cap layers wherein the first cap layer is composed of a nonmagnetic metal and the second cap layer is composed of iron oxide. Both cap layers are specular reflectors which reflect conduction electrons back into a spin scattering region of a spin valve sensor without increasing the uniaxial anisotropy HKof a free layer structure within the spin valve sensor. rack of determining step (a) is one of a plurality of adjacent data tracks supported by the rotatable disc surface and in which the determining step (a) comprising steps of: (a1) selecting the data track from among the plurality of adjacent data tracks of the rotatable disc surface; (a2) measuring and storing a plurality of position error signals measurements for each of the plurality of servo sectors of the selected data track for use in calculating the total written-in repeatable run-out error value for each of the plurality of servo sectors of the selected data track; (a3) manipulating the plurality of stored position error signal measurements for each of the plurality of servo sectors to determine the total written-in repeatable run-out error value for each of the plurality of servo sectors; and (a4) storing the total written-in repeatable run-out error value for each of the plurality of servo sectors for use in isolating the repeatable error value component of the total written-in repeatable run-out error value for each of the plurality of servo sectors. 3. The method of claim 2 in which each of the plurality of servo sectors of the selected data track is adjacent one of the plurality of servo sectors of a data track adjacent the selected data track, wherein a plurality of adjacent servo sectors form a servo wedge across the rotatable disc surface and in which isolating step (b) of claim 1 comprises steps of: (b1) repeating the determining steps (a1) through (a4) of claim 2 for the plurality of adjacent data tracks of the rotatable disc surface; and (b2) processing the stored total written-in repeatable run-out error value components of each of the plurality of servo sectors of the servo wedge to isolate the repeatable error value component of the total written-in repeatable run-out error value for the selected servo sector. 4. The method of claim 1 in which the disc drive comprises a servo loop having servo control electronics, the data track of determining step (a) is one of a plurality of adjacent data tracks supported by the rotatable disc surface, the repeatable error value component of isolating step (b) is a time domain repeatable error value component, wherein each of the plurality of data tracks support a plurality of servo sectors, and in which the compensating step (e) comprises steps of: (e1) determining a transfer function value for each selected frequency of the servo loop of the disc drive; (e2) deriving the time domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e3) transforming each of the time domain repeatable error value components for each of the plurality of servo sectors into a frequency domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e4) factoring each of the frequency domain repeatable error value components of each of the plurality of servo sectors by the transfer function for a selected one of the selected frequencies to produce a frequency domain repeatable error compensation value for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e5) applying an inverse transform to each of the frequency domain repeatable error compensation values to produce a time domain repeatable error compensation value for each of the servo sectors of each of the plurality of adjacent data tracks; (e6) storing each of the time domain repeatable error compensation values for use in generating and applying a cross track repeatable compensation signal to the servo control electronics of the servo loop to compensate for each of the time domain repeatable error value components of each of the servo sectors of each of the plurality of adjacent data tracks; and (e7) generating and applying the cross track repeatable compensation signal to the servo loop, compensating for each of the time domain re peatable error value components for each of the servo sectors of each of the plurality of adjacent data tracks. 5. The method of claim 4 in which the non-repeatable error value component of separating step (c) of claim 1 is a time domain non-repeatable error value component, and in which the compensating step (e) further comprising steps of: (e8) determining the non-repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e9) transforming each of the time domain non-repeatable error value components for each of the plurality of servo sectors into a frequency domain non-repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e10) factoring each of the frequency domain non-repeatable error value components of each of the plurality of servo sectors by the transfer function for a selected one of the selected frequencies to produce a frequency domain non-repeatable error compensation value for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e11) applying an inverse transform to each of the frequency domain non-repeatable error compensation values to produce a time domain non-repeatable error compensation value for each of the servo sectors of each of the plurality of adjacent data tracks; (e12) storing each of the time domain non-repeatable error compensation values for use in generating and applying a cross track non-repeatable compensation signal to the servo loop to compensate for each of the time domain non-repeatable error value components for each of the servo sectors of each of the plurality of adjacent data tracks; and (e13) generating and applying the cross track non-repeatable compensation signal to the servo loop compensating for each of the time domain non-repeatable error value components for each of the servo sectors of each of the plurality of adjacent data tracks. 6. The method of claim 1 in which the compensation signals of providing step (d) are a combined compromised error compensation signal having a predetermined cross track repeatable compensation signal portion and a cross track non-repeatable compensation signal portion. 7. The method of claim 6 in which the cross track non-repeatable compensation signal portion of the combined compromised error compensation signal is greater than the cross track repeatable compensation signal portion of the combined compromised error compensation signal of providing step (d). 8. The method of claim 6 in which the cross track non-repeatable compensation signal portion of the combined compromised error compensation signal is less than the cross track repeatable compensation signal portion of the combined compromised error compensation signal of providing step (d). 9. A disc drive having a rotatable disc surface, a read/write head positionably adjacent the rotatable disc surface and a servo loop for positioning the read/write head relative to a rotatable disc surface, the servo loop comprising: a servo track with a plurality of servo sectors supported by the rotatable disc surface for providing servo control information; a read element of the read/write head for reading the servo control information from the plurality of servo sectors of the servo track and producing a head measurement signal; a reference signal for combining with the head measurement signal to produce the position error signal; a servo control circuit for generating a position control signal in response to the servo position error signal; a positioning mechanism communicating with the servo control circuit for moving the read/write head relative to the rotatable disc surface in response to the position control signal; a repeatable run-out error compensation circuit for generating and applying an initial cross track repeatable compensation signal to the head measurement signal; and a non-repeatable run-out err or compensation circuit for generating and applying an initial cross track non-repeatable compensation signal to the head measurement signal. 10. The disc drive of claim 9 in which the positioning mechanism comprises: a head stack assembly having a bearing assembly communicating with at least one actuator arm supporting a load arm that supports at least one read/write head; and a voice coil motor having an actuator coil immersed in a magnetic field generated by a magnet assembly having a permanent magnet secured between a bottom pole piece and a top pole piece forming a magnetically permeable flux path communicating with the servo control circuit, the actuator coil responsive to the position control signal for positioning the read/write head relative to the rotatable disc surface. 11. The disc drive of claim 9 in which the rotatable disc surface has a plurality of generally concentric portions supporting a plurality of adjacent servo tracks each with a plurality of servo sectors, the plurality of adjacent servo tracks adjacent the servo track and in which the initial cross track repeatable compensation signal is provided by steps comprising: (a) determining transfer function values for the servo loop of the disc drive at select frequencies; (b) deriving a time domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (c) transforming each of the time domain repeatable error value components for each of the plurality of servo sectors into a frequency domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (d) factoring each of the frequency domain repeatable error value components of each of the plurality of servo sectors by the transfer function for a selected one of the select frequencies to produce a frequency domain repeatable error compensation value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (e) applying an inverse transform to each of the frequency domain repeatable error compensation values to produce a time domain repeatable error compensation value for each of the servo sectors of each of the plurality of adjacent servo tracks; (f) storing each of the time domain repeatable error compensation values for use in generating the initial cross track repeatable compensation signal for application to the servo control circuit of the servo loop to compensate for each of the time domain repeatable error value components of each of the servo sectors of each of the plurality of adjacent servo tracks; and (g) generating the initial cross track repeatable compensation signal to compensate for each of the time domain repeatable error value components for each of the servo sectors of each of the plurality of adjacent servo tracks. 12. The disc drive of claim 9 in which the rotatable disc surface has a plurality of generally concentric portions supporting a plurality of adjacent servo tracks each with a plurality of servo sectors, the plurality of adjacent servo tracks adjacent the servo track and in which the initial cross track non-repeatable compensation signal is provided by steps comprising: (a) determining transfer function values for the servo loop of the disc drive at select frequencies; (b) obtaining a total time domain written-in repeatable run-out error value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (c) deriving a time domain repeatable run-out error value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (d) factoring the total time domain written-in repeatable run-out error value by the time domain repeatable run-out error value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks to isolate a time domain non-repeatable error value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (e) transforming each of the time domain non-repeatable error value components for each of the plurality of servo sectors into a frequency domain non-repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (f) factoring each of the frequency domain non-repeatable error value components of each of the plurality of servo sectors by the transfer function for a selected one of the select frequencies to produce a frequency domain non-repeatable error compensation value for each of the plurality of servo sectors of each of the plurality of adjacent servo tracks; (g) applying an inverse transform to each of the frequency domain non-repeatable error compensation values to produce a time domain non-repeatable error compensation value for each of the servo sectors of each of the plurality of adjacent servo tracks; (h) storing each of the time domain non-repeatable error compensation values for use in generating the initial cross track non-repeatable compensation signal for application to the servo control circuit of the servo loop to compensate for each of the time domain non-repeatable error value components of each of the servo sectors of each of the plurality of adjacent servo tracks; and (i) generating the initial cross track non-repeatable compensation signal to compensate for each of the time domain non-repeatable error value components for each of the servo sectors of each of the plurality of adjacent servo tracks. 13. A disc drive having a rotatable disc surface supporting a plurality of adjacent data tracks, a read/write head positionably adjacent the plurality of adjacent data tracks, a servo loop comprising a repeatable run-out error compensation circuit, a non-repeatable run-out error compensation circuit and servo control electronics for positioning the read/write head relative to the plurality of adjacent data tracks, each data track built by steps comprising: steps for isolating a repeatable error value component and a non-repeatable error value component of a total repeatable written-in repeatable run-out error value written into the rotatable disc surface of the disc drive; steps for applying an initial cross track repeatable compensation signal to the servo control electronics to correct for the repeatable error value component of a total repeatable written-in repeatable run-out error value; and steps for applying an initial cross track non-repeatable compensation signal to the servo control electronics to correct for the non-repeatable error value component of a total repeatable written-in repeatable run-out error value. 14. The disc drive of claim 13 in which each of the plurality of adjacent data tracks provide a plurality of servo sectors each adjacent a respective servo sector of the adjacent data tracks, a plurality of adjacent servo sectors forming a servo wedge, the total repeatable written-in repeatable run-out error value is written into each of the plurality of servo sectors and in which the step for isolating the repeatable and the non-repeatable error value components of the total repeatable written-in repeatable run-out error value written into the rotatable disc surface of the disc drive comprises steps of: (a) selecting a data track from among the plurality of adjacent data tracks of the rotatable disc surface; (b) measuring and storing a plurality of position error signals measurements for each servo sector of the plurality of servo sectors for use in calculating the total repeatable written-in repeatable run-out error value written into each servo sector of the selected data track; (c) normalizing the plurality of stored position error signal measurements for each servo sector of the plurality of servo sectors to determine the total repeatable written-in repeatable run-out error value for each servo sector of the selected data track; (d) storing th e total repeatable written-in repeatable run-out error value for each servo sector for use in isolating the repeatable error value component of the total repeatable written-in repeatable run-out error value for each servo sector of the selected data track; (e) repeating the above steps (a) through (d) for the plurality of adjacent data tracks selected from the rotatable disc surface; (f) standardizing the stored total repeatable written-in repeatable run-out error value for each servo sector of each of the plurality of adjacent data tracks to isolate the repeatable error value component of the total repeatable written-in repeatable run-out error value for each servo sector of each of the plurality of adjacent data tracks; and (g) removing the isolated repeatable error value component from the total repeatable written-in repeatable run-out error value for each servo sector of each of the plurality of adjacent data tracks, to provide a non-repeatable run-out error value component from the total repeatable written-in repeatable run-out error value for each servo sector of each of the plurality of adjacent data tracks. 15. The disc drive of claim 13 in which the repeatable error value component is a time domain repeatable run-out error value component, each of the plurality of adjacent data tracks support a plurality of servo sectors, and in which the steps for applying an initial cross track repeatable compensation signal to the servo control electronics comprising steps of: (a) determining transfer function values for the servo loop of the disc drive at select frequencies; (b) deriving a time domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (c) transforming each of the time domain repeatable error value components for each of the plurality of servo sectors into a frequency domain repeatable error value component for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (d) factoring each of the frequency domain repeatable error value components of each of the plurality of servo sectors by the transfer function for a selected one of the select frequencies to produce a frequency domain repeatable error compensation value for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (e) applying an inverse transform to each of the frequency domain repeatable error compensation values to produce a time domain repeatable error compensation value for each of the servo sectors of each of the plurality of adjacent data tracks; (f) storing each of the time domain repeatable error compensation values for use in generating the initial cross track repeatable compensation signal for application to the servo control circuit of the servo loop to compensate for each of the time domain repeatable error value components of each of the servo sectors of each of the plurality of adjacent data tracks; and (g) generating and applying the initial cross track repeatable compensation signal to compensate for each of the time domain repeatable error value components for each of the servo sectors of each of the plurality of adjacent data tracks. 16. The disc drive of claim 13 in which the non-repeatable error value component is a time domain non-repeatable run-out error value component, each of the plurality of adjacent data tracks support a plurality of servo sectors, and in which the steps for applying an initial cross track non-repeatable compensation signal to the servo control electronics comprising steps of: (a) determining transfer function values for the servo loop of the disc drive at select frequencies; (b) obtaining a total time domain written-in repeatable run-out error value for each of the plurality of servo sectors of each of the plurality of adjacent data tracks; (c) deriving a time domain repeatable run-out error value for each of the plurality of servo sectors of each of