Magnetic disk device having first and second assist elements and write operation method

A magnetic disk device comprising:

• a disk;
• a head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a gap, a first assist element that is disposed in the gap, and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction;
• and
• a controller configured to:
• cause a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk;
• and
• cause a second assist energy from the second assist element to be applied to the disk and affect the coercive force of the disk,
• wherein the first assist energy is different from the second assist energy, and
• wherein the first assist element comprises a high-frequency assist element that generates and applies a first high-frequency magnetic field to the disk as the first assist energy and the second assist element comprises a high-frequency assist element that generates and applies a second high-frequency magnetic field to the disk as the second assist energy.

A magnetic disk device comprising:

• a disk;
• a head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a pap, a first assist element that is disposed in the gap, and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction;
• and
• a controller configured to:
• cause a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk;
• and
• cause a second assist energy from the second assist element to be applied to the disk and affect the coercive force of the disk,
• wherein the first assist energy is different from the second assist energy, and
• wherein the first assist element comprises a thermal assist element that irradiates the disk with first near-field light as the first assist energy and the second assist element comprises a thermal assist element that irradiates the disk with second near-field light as the second assist energy.

A write operation method that is applied to a magnetic disk device,

• the magnetic disk device including a disk and a head,
• the head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a gap, a first assist element that is disposed in the gap, and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction, and
• the write operation method comprising:
• causing a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk;
• causing a second assist energy from the second assist element to be applied to the disk and affect the coercive force of the disk;
• and
• determining the first assist energy and the second assist energy based on an overwrite direction in which second data overwrites a portion of first data in a radial direction of the disk,
• wherein the first assist energy is different from the second assist energy, and
• wherein the second direction corresponds to the radial direction of the disk.