A method is disclosed for reducing disk expansion effects while writing spiral reference patterns on a disk. The disk drive comprises control circuitry and a head disk assembly (HDA). In the method, an external spiral servo writer is used to control a radial location of the head for writing a plurality of the spiral reference patterns in an order such that at least two of the spiral reference patterns are not written temporally sequential to an adjacent spiral reference pattern. The head internal to the disk drive is used to read the spiral reference patterns in order to write product servo bursts to the disk, thereby defining a plurality of radially spaced, concentric data tracks.

 
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< Magnetic head having a heater circuit for thermally-assisted writing

< Data recording medium, and data reproducing apparatus

> Method for reducing disk thermal expansion effects while writing reference spiral servo patterns to a disk of a disk drive

> Methods for limiting channel control values to thereby improve servo-demodulation robustness

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