Magnetic head and magnetic recording device

Abstract

It is made possible to restrict the variation of the oscillation frequency of a spin torque oscillator placed in the vicinity of the recording magnetic pole. A magnetic head includes: a recording magnetic pole to generate a recording magnetic field; a spin torque oscillator formed in the vicinity of the recording magnetic pole; and a magnetic field applying unit configured to apply a magnetic field to the spin torque oscillator. The magnetic field applied to the spin torque oscillator by the magnetic field applying unit is perpendicular to a recording magnetic field generated from the recording magnetic pole.

1 . A magnetic head comprising:
 a recording magnetic pole to generate a recording magnetic field;   a spin torque oscillator formed in the vicinity of the recording magnetic pole; and   a magnetic field applying unit configured to apply a magnetic field to the spin torque oscillator,   the magnetic field applied to the spin torque oscillator by the magnetic field applying unit being perpendicular to a recording magnetic field generated from the recording magnetic pole.   
   
   
       2 . The head according to  claim 1 , wherein the magnetic field applying unit is formed with an electromagnet that includes a magnetic core having a void, and an electromagnetic coil that is designed to surround the magnetic core and excite the magnetic core, and applies a magnetic field generated from the magnetic core to the spin torque oscillator. 
   
   
       3 . The head according to  claim 1 , wherein the magnetic field applying unit is formed with hard bias film. 
   
   
       4 . The head according to  claim 1 , wherein the magnetic applying unit is further away from the magnetic recording medium than an air bearing surface of the spin torque oscillator facing the magnetic recording medium. 
   
   
       5 . The head according to  claim 1 , further comprising
 a shield magnetically connected to the recording magnetic pole, and having a portion extending in a direction parallel to an air bearing surface of the recording magnetic pole.   
   
   
       6 . The head according to  claim 5 , wherein the spin torque oscillator is placed between the shield and the recording magnetic pole. 
   
   
       7 . A magnetic head comprising:
 a recording magnetic pole to generate a recording magnetic field;   a spin torque oscillator formed in the vicinity of the recording magnetic pole; and   a magnetic field applying unit provided at either end portion of the spin torque oscillator in a direction perpendicular to a direction parallel to a line connecting the recording magnetic pole and the spin torque oscillator in a plane parallel to an air bearing surface, the magnetic field applying unit configured to apply a magnetic field to the spin torque oscillator,   the spin torque oscillator including:   a first magnetic layer comprising at least one layer of magnetic film;   a second magnetic layer comprising at least one layer of magnetic film;   an intermediate layer provided between the first magnetic layer and the second magnetic layer; and   an electrode comprising a first electrode layer placed on a face of the first magnetic layer on the opposite side from the intermediate layer, and a second electrode layer placed on a face of the second magnetic layer on the opposite side from the intermediate layer, the electrode being capable of applying a current flowing in a direction perpendicular to film planes of the first magnetic layer, the intermediate layer, and the second magnetic layer,   the first electrode layer, the first magnetic layer, the intermediate layer, the second magnetic layer, and the second electrode layer being stacked in a direction parallel to a direction connecting the two end portions of the spin torque oscillator.   
   
   
       8 . The head according to  claim 7 , wherein the magnetic field applying unit is formed with an electromagnet that includes a magnetic core having a void, and an electromagnetic coil that is designed to surround the magnetic core and excite the magnetic core, and applies a magnetic field generated from the magnetic core to the spin torque oscillator. 
   
   
       9 . The head according to  claim 7 , wherein the magnetic field applying unit is formed with hard bias film. 
   
   
       10 . The head according to  claim 7 , wherein the magnetic applying unit is further away from the magnetic recording medium than an air bearing surface of the spin torque oscillator facing the magnetic recording medium. 
   
   
       11 . The head according to  claim 7 , further comprising
 a shield magnetically connected to the recording magnetic pole, and having a portion extending in a direction parallel to an air bearing surface of the recording magnetic pole.   
   
   
       12 . The head according to  claim 11 , wherein the spin torque oscillator is placed between the shield and the recording magnetic pole. 
   
   
       13 . A magnetic head comprising:
 a recording magnetic pole to generate a recording magnetic field;   a spin torque oscillator formed in the vicinity of the recording magnetic pole; and   a magnetic field applying unit provided at either end portion of the spin torque oscillator in a direction perpendicular to a direction parallel to a line connecting the recording magnetic pole and the spin torque oscillator in a plane parallel to an air bearing surface, the magnetic field applying unit configured to apply a magnetic field to the spin torque oscillator,   the spin torque oscillator including:   a first magnetic layer comprising at least one layer of magnetic film;   a second magnetic layer comprising at least one layer of magnetic film;   an intermediate layer provided between the first magnetic layer and the second magnetic layer; and   an electrode comprising a first electrode layer placed on a face of the first magnetic layer on the opposite side from the intermediate layer, and a second electrode layer placed on a face of the second magnetic layer on the opposite side from the intermediate layer, the electrode being capable of applying a current flowing in a direction perpendicular to film planes of the first magnetic layer, the intermediate layer, and the second magnetic layer,   the first electrode layer, the first magnetic layer, the intermediate layer, the second magnetic layer, and the second electrode layer being stacked in a direction perpendicular to a direction connecting the two end portions of the spin torque oscillator.   
   
   
       14 . The head according to  claim 13 , wherein the magnetic field applying unit is formed with an electromagnet that includes a magnetic core having a void, and an electromagnetic coil that is designed to surround the magnetic core and excite the magnetic core, and applies a magnetic field generated from the magnetic core to the spin torque oscillator. 
   
   
       15 . The head according to  claim 13 , wherein the magnetic field applying unit is formed with hard bias film. 
   
   
       16 . The head according to  claim 13 , wherein the magnetic applying unit is further away from the magnetic recording medium than an air bearing surface of the spin torque oscillator facing the magnetic recording medium. 
   
   
       17 . The head according to  claim 13 , further comprising
 a shield magnetically connected to the recording magnetic pole, and having a portion extending in a direction parallel to an air bearing surface of the recording magnetic pole.   
   
   
       18 . The head according to  claim 17 , wherein the spin torque oscillator is placed between the shield and the recording magnetic pole. 
   
   
       19 . A magnetic recording device comprising:
 a magnetic recording medium; and   the magnetic head according to  claim 1 ,   wherein writing on the magnetic recording medium is performed with the use of the magnetic recording head.   
   
   
       20 . The device according to  claim 19 , wherein the spin torque oscillator is placed on a trailing side of the recording magnetic pole. 
   
   
       21 . The device according to  claim 19 , wherein the spin torque oscillator is placed on a leading side of the recording magnetic pole. 
   
   
       22 . The device according to  claim 19 , wherein the magnetic recording medium is a discrete track medium that has a plurality of tracks arranged in parallel with one another, and a nonmagnetic portion provided between the adjacent tracks. 
   
   
       23 . The device according to  claim 19 , wherein the magnetic recording medium is a discrete bit medium that has a plurality of magnetic dots, and a nonmagnetic portion provided between the magnetic dots.