Patent ID: 8693127

Claim:
A method, comprising: applying a varying current to a servo write head having first and second write gaps to alternately AC-erase and write sets of servo marks to regions of a servo track of a magnetic recording medium proximate to said first and second write gaps, each servo mark of said sets of servo marks comprising first and second abutting magnetic domains of opposite magnetization directions, said magnetic recording medium moving with respect to said first and second write gaps in a recording direction, said magnetic recording medium being either (i) a perpendicular magnetic storage medium having magnetic particles with their easy axes oriented perpendicular to a top surface of said perpendicular storage medium or (ii) a non-oriented magnetic storage medium having magnetic particles with their easy axes randomly oriented relative to a top surface of said non-orientated magnetic storage medium; and wherein applying said varying current includes, in the following order: (a) for a length of time T 1 , applying a first oscillating current of high frequency to AC-erase regions of the servo track across from said first and second write gaps, said first oscillating current oscillating between a negative current and a positive current; (b) for a length of time T 2 , applying N current steps where the current holds at a first polarity for a first period of time, steps to a second polarity and holds at the second polarity for a second period of time, to write a set of N servo marks to the servo track from each of said first and second write gaps; and between each of said N current steps applying second oscillating currents of high frequency to AC-erase regions of the servo track across from said first and second write gaps, said second oscillating currents oscillating between a negative current and a positive current, where N is a positive integer equal to or greater than one; (c) for a length of time T 3 , applying a third oscillating current of high frequency to AC-erase regions of the servo track across from said first and second write gaps, said third oscillating current oscillating with decreasing amplitude between a negative current and a positive current; (d) for a length of time T 4 , applying zero current or a current close to zero, so that the magnetic state of said magnetic recording medium does not change, thereby avoiding overwriting servo marks; and repeating (a) through (d) multiple times.