Current drive type magnetic head and disk drive with the same

1. A magnetic head comprising:

a magnetic core comprising a main pole configured to apply a recording magnetic field perpendicular to a recording layer of a recording medium, and a return pole opposed to the main pole with a magnetic gap therebetween, the return pole configured to return magnetic flux from the main pole and form a magnetic circuit in conjunction with the main pole;

a coil configured to generate, by a first current, the magnetic flux in the magnetic circuit;

a nonmagnetic electrically conductive layer formed by disposing a nonmagnetic material in the magnetic gap between the return pole and an end portion of the main pole on a side of the recording medium, and configured to electrically connect the main pole and the return pole; and

a wiring configured to supply a second current in series through the main pole, the nonmagnetic electrically conductive layer, and the return pole.

2. The magnetic head of claim 1 , wherein the magnetic core comprises a junction configured to magnetically connect the main pole and the return pole, and an insulating layer arranged within the junction to electrically insulate the main pole and the return pole from each other.

3. The magnetic head of claim 2 , further comprising second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium and magnetically separated from the main pole, the second return poles being connected to the first return pole, wherein the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the return poles.

4. The magnetic head of claim 3 , further comprising a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the return pole.

5. The magnetic head of claim 1 , further comprising second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium, magnetically separated from the main pole and connected to the return pole, and a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the return pole, wherein the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the third return pole, and the current source is connected to the main pole and the third return pole.

6. The magnetic head of claim 1 , wherein the return pole comprises second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium, and magnetically separated from the main pole, the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the second return poles, and the current source is connected to the main pole and the second return poles.

7. The magnetic head of claim 6 , wherein the return pole comprises a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the second return poles, and the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the second and third return poles.

8. A disk drive comprising:

a disk recording medium comprising a magnetic recording layer having a magnetic anisotropy perpendicular to a surface of the medium;

a mechanical unit configured to rotate the recording medium;

a current source; and

a magnetic head configured to process data on the medium,

the magnetic head comprising:

a magnetic core comprising a main pole configured to apply a recording magnetic field perpendicular to a recording layer of a recording medium, and a return pole opposed to the main pole with a magnetic gap therebetween, the return pole configured to return magnetic flux from the main pole and form a magnetic circuit in conjunction with the main pole,

a coil configured to generate, by a first current, the magnetic flux in the magnetic circuit formed of the main pole and the return pole,

a nonmagnetic electrically conductive layer formed by disposing a nonmagnetic material in the magnetic gap between the return pole and an end portion of the main pole on the recording medium side, and configured to electrically connect the main pole and the return pole, and

a wiring configured to supply a second current from the current source in series through the main pole, the nonmagnetic electrically conductive layer, and the return pole.

9. The disk drive of claim 8 , wherein the magnetic core comprises a junction configured to magnetically connect the main pole and the return pole, and an insulating layer arranged within the junction to electrically insulate the main pole and the return pole from each other.

10. The disk drive of claim 9 , further comprising second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium and magnetically separated from the main pole, the second return poles being connected to the first return pole, wherein the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the return poles.

11. The disk drive of claim 10 , further comprising a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the return pole.

12. The disk drive of claim 8 , further comprising second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium, magnetically separated from the main pole and connected to the return pole, and a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the return pole, wherein the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the third return pole, and the current source is connected to the main pole and the third return pole.

13. The disk drive of claim 8 , further comprising a control unit which controls a time period for current supply in which the main pole, the nonmagnetic electrically conductive layer, and the return pole are electrically connected in series and which controls a time period for energizing the coil.

14. The disk drive of claim 13 , wherein the control unit comprises a computation unit configured to detect a bit-error rate of a signal recorded on the recording medium and to compare the detected rate with a threshold rate, and a current control unit and a current generation unit each configured to adjust a current to be supplied to the main pole and the time period for the current supply when the bit-error rate is higher than the threshold rate.

15. The disk drive of claim 13 , wherein the return pole comprises second return poles disposed individually on the opposite sides of the main pole transversely relative to a track of the recording medium, and magnetically separated from the main pole, the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the second return poles, and the current source is connected to the main pole and the second return poles.

16. The disk drive of claim 15 , wherein the return pole comprises a third return pole arranged on the leading side of the main pole and magnetically separated from the main pole and the second return poles, and the nonmagnetic electrically conductive layer is arranged between an end portion of the main pole on the recording medium side and the second and third return poles.