Disk-like magnetic recording medium and magnetic recording and reproducing device

A disk-like magnetic recording medium comprising:

• a disk-like substrate;
• a first soft magnetic layer provided on the disk-like substrate;
• a nonmagnetic spacer layer provided on the first soft magnetic layer;
• a second soft magnetic layer provided on the nonmagnetic spacer layer and antiferromagnetically exchange-coupled with the first soft magnetic layer via the nonmagnetic spacer layer;
• and
• a magnetic recording layer provided, on the second soft magnetic layer, wherein
• a value of an exchange coupling magnetic field Hbias periodically changes with respect to a thickness of the nonmagnetic spacer layer, and
• a thickness x of the nonmagnetic spacer layer increases from an inner circumferential area toward an outer circumferential area of the disk-like magnetic recording medium and satisfies a relationship expressed as a≤x<b where a is a thickness of the nonmagnetic spacer layer at a first peak at which the exchange coupling magnetic field Hbias has a maximum value, c is a thickness of the nonmagnetic spacer layer at a second peak at which the exchange coupling magnetic field Hbias has a maximum value after the first peak, and b is a thickness of the nonmagnetic spacer layer when the exchange coupling magnetic field Hbias has a minimum value between the first peak and the second peak.

A magnetic recording and reproducing device comprising:

• a disk-like magnetic recording medium comprising:
• a disk-like substrate;
• a first soft magnetic layer provided on the disk-like substrate;
• a nonmagnetic spacer layer provided on the first soft magnetic layer;
• a second soft magnetic layer provided on the nonmagnetic spacer layer and antiferromagnetically exchange-coupled with the first soft magnetic layer via the nonmagnetic spacer layer;
• and
• a magnetic recording layer provided on the second soft magnetic layer, wherein
• strength of an exchange coupling magnetic field Hbias decreases from an inner circumferential area toward an outer circumferential area of the disk-like magnetic recording medium;
• a driver which rotates the recording medium;
• and
• a magnetic head which includes a recording head which performs information processing with respect to the recording medium.

A magnetic recording and reproducing device comprising:

• a disk-like magnetic recording medium comprising:
• a disk-like substrate;
• a first soft magnetic layer provided on the disk-like substrate;
• a nonmagnetic spacer layer provided on the first soft magnetic layer;
• a second soft magnetic layer provided on the nonmagnetic spacer layer and antiferromagnetically exchange-coupled with the first soft magnetic layer via the nonmagnetic spacer layer;
• and
• a magnetic recording layer provided on the second soft magnetic layer, wherein
• a value of an exchange coupling magnetic field Hbias periodically changes with respect to a thickness of the nonmagnetic spacer layer, and
• a thickness x of the nonmagnetic spacer layer increases from the inner circumferential area toward the outer circumferential area and satisfies a relationship expressed as a≤x<b where a is a thickness of the nonmagnetic spacer layer at a first peak at which the exchange coupling magnetic field Hbias has a maximum value, c is a thickness of the nonmagnetic spacer layer at a second peak at which the exchange coupling magnetic field Hbias has a maximum value after the first peak, and b is a thickness of the nonmagnetic spacer layer when the exchange coupling magnetic field Hbias has a minimum value between the first peak and the second peak;
• a driver which rotates the recording medium;
• and
• a magnetic head which includes a recording head which performs information processing with respect to the recording medium.