Servo write head for writing servo patterns having opposite- polarity bars

A servo write bar, comprising:

• one or more servo write heads, each of the one or more servo write heads comprising:
• a first end pole;
• a second end pole;
• a center pole disposed between the first and second end poles, the center pole being spaced from the first end pole by a first gap and spaced from the second end pole by a second gap;
• a coil disposed around the center pole and within the first and second gaps;
• a top pole disposed in contact with the first end pole, the second end pole, and the center pole, the top pole comprising a first channel aligned with the first gap and a second channel aligned with the second gap, wherein the first gap has a greater width than the first channel and the second gap has a greater width than the second channel;
• and
• a thin plate disposed over the top pole, the thin plate comprising a servo pattern disposed over the coil, the servo pattern comprising a first servo line disposed over the first channel and a second servo line disposed over the second channel, wherein the first channel has a greater width than the first servo line and the second channel has a greater width than the second servo line.

A servo write bar, comprising:

• one or more servo write heads, each of the one or more servo write heads comprising:
• a first end pole;
• a second end pole;
• a center pole disposed between the first and second end poles, the center pole being spaced from the first end pole by a first gap and spaced from the second end pole by a second gap;
• a coil disposed around the center pole and within the first and second gaps;
• a current source coupled to the coil;
• a top pole disposed over the coil, the first end pole, the second end pole, and the center pole, the top pole comprising a first channel aligned with the first gap and a second channel aligned with the second gap, wherein the first gap has a greater width than the first channel and the second gap has a greater width than the second channel;
• and
• a thin plate disposed over the top pole, the thin plate comprising a servo pattern, the servo pattern comprising a first servo line disposed over the first channel and a second servo line disposed over the second channel, wherein the first channel has a greater width than the first servo line and the second channel has a greater width than the second servo line.