Microwave-assisted magnetic recording head, method of manufacturing the same, magnetic head assembly using the same, and magnetic recording/reproduction apparatus

1. A magnetic recording head manufacturing method comprising:

forming a spin torque oscillator layer on a main magnetic pole layer;

forming a mask on the spin torque oscillator layer;

processing the spin torque oscillator layer by performing ion beam etching on the spin torque oscillator layer through the mask; and

decreasing a saturation flux density by partially modifying the main magnetic pole layer through the mask to form an unmodified main magnetic pole portion covered with the mask, and a modified portion around the main magnetic pole.

2. The method according to claim 1 , wherein the main magnetic pole layer in the modified portion has a saturation flux density of not more than 5 kG.

3. The method according to claim 1 , wherein the modifying the main magnetic pole layer is performed using at least one ion selected from the group consisting of fluorine, chlorine, bromine, oxygen, nitrogen, and boron.

4. The method according to claim 1 , further comprising forming a cap layer made of a nonmagnetic metal material on the spin torque oscillator layer, before the forming the mask on the spin torque oscillator layer.

5. The head according to claim 1 , wherein the modified portion has a saturation flux density of not more than 5 kG.

6. A magnetic recording head comprising:

a main magnetic pole portion;

a modified portion formed around the main magnetic pole portion by modifying the same material as that of the main magnetic pole portion by using at least one ion selected from the group consisting of fluorine, chlorine, bromine, oxygen, nitrogen, and boron such that a saturation flux density decreases; and

a spin torque oscillator layer formed on the main magnetic pole portion.

7. A magnetic head assembly comprising:

a magnetic recording head comprising

a main magnetic pole portion,

a modified portion formed around the main magnetic pole portion by modifying the same material as that of the main magnetic pole portion by using at least one ion selected from the group consisting of fluorine, chlorine, bromine, oxygen, nitrogen, and boron such that a saturation flux density decreases, and

a spin torque oscillator layer formed on the main magnetic pole portion;

a head slider on which the magnetic recording head is mounted;

a suspension having one end on which the head slider is mounted; and

an actuator arm connected to the other end of the suspension.

8. The assembly according to claim 7 , wherein the modified portion has a saturation flux density of not more than 5 kG.

9. A magnetic recording/reproduction apparatus comprising:

a magnetic recording medium; and

a magnetic head assembly comprising

a magnetic recording head comprising a main magnetic pole portion, a modified portion formed around the main magnetic pole portion by modifying the same material as that of the main magnetic pole portion by using at least one ion selected from the group consisting of fluorine, chlorine, bromine, oxygen, nitrogen, and boron such that a saturation flux density decreases, and a spin torque oscillator layer formed on the main magnetic pole portion,

a head slider on which the magnetic recording head is mounted,

a suspension having one end on which the head slider is mounted, and

an actuator arm connected to the other end of the suspension.

10. The apparatus according to claim 9 , wherein the modified portion has a saturation flux density of not more than 5 kG.