A microwave-assisted magnetic recording (MAMR) write head has a spin-torque oscillator (STO) and a ferromagnetic compensation layer between the write pole and trailing shield. The compensation layer is separated from the free layer by a nonmagnetic barrier layer that prevents spin-polarized electrons from the free layer from reaching the compensation layer. The compensation layer may be located between the write pole and the free layer. Electrons become spin-polarized by the compensation layer and are reflected back from the write pole across a nonmagnetic spacer layer. This causes the magnetization of the compensation layer to flip and become antiparallel to the magnetization of the free layer. The compensation layer thus generates a DC offset field that compensates for the negative effect of the DC shunting field from the free layer.

A microwave-assisted magnetic recording (MAMR) write head has a spin-torque oscillator (STO) and a ferromagnetic compensation layer between the write pole and trailing shield. The compensation layer is separated from the free layer by a nonmagnetic barrier layer that prevents spin-polarized electrons from the free layer from reaching the compensation layer. The compensation layer may be located between the write pole and the free layer. Electrons become spin-polarized by the compensation layer and are reflected back from the write pole across a nonmagnetic spacer layer. This causes the magnetization of the compensation layer to flip and become antiparallel to the magnetization of the free layer. The compensation layer thus generates a DC offset field that compensates for the negative effect of the DC shunting field from the free layer.

According to one embodiment, a magnetic disk device comprises a magnetic head including a main pole, an auxiliary magnetic pole, side shields disposed on both sides of the main pole in a track width direction with a side gap therebetween, a high frequency oscillation element disposed in the write gap between the main pole and the auxiliary magnetic pole, and a magnetic flux control element disposed in the side gap between the main pole and the side shield to control oscillation frequency of the high frequency oscillation element, an oscillation element controller configured to control bias current supplied to the high frequency oscillation element, and a magnetic flux control element controller configured to control bias current supplied to the magnetic flux control element.

According to one embodiment, a magnetic disk device comprises a magnetic head including a main pole, an auxiliary magnetic pole, side shields disposed on both sides of the main pole in a track width direction with a side gap therebetween, a high frequency oscillation element disposed in the write gap between the main pole and the auxiliary magnetic pole, and a magnetic flux control element disposed in the side gap between the main pole and the side shield to control oscillation frequency of the high frequency oscillation element, an oscillation element controller configured to control bias current supplied to the high frequency oscillation element, and a magnetic flux control element controller configured to control bias current supplied to the magnetic flux control element.

An apparatus includes a polarizer of a spin-torque oscillator (STO). The polarizer has a perpendicular magnetic anisotropy (PMA) and is configured to receive a first signal having a current density of between 0.5110.sup.6 amps per square centimeter (amps/cm.sup.2) and 15.310.sup.6 amps/cm.sup.2. The apparatus also includes a magnetically soft oscillating region including an antiferromagnetic (AF) coupling layer coupling a first free layer to a second free layer and located between the polarizer and a reference region. The reference region is configured to output a second signal responsive to the first signal, the second signal having a frequency less than 8 gigahertz (GHz).

An apparatus includes a polarizer, a first free layer, a second free layer, and an antiferromagnetic (AF) coupling layer. The polarizer has a perpendicular magnetic anisotropy (PMA). The polarizer, the first free layer, the second free layer, and the AF coupling layer are included in a spin-torque oscillator (STO). The AF coupling layer is positioned between the first free layer and the second free layer.

An apparatus includes a polarizer, a first free layer, a second free layer, and an antiferromagnetic (AF) coupling layer. The polarizer has a perpendicular magnetic anisotropy (PMA). The polarizer, the first free layer, the second free layer, and the AF coupling layer are included in a spin-torque oscillator (STO). The AF coupling layer is positioned between the first free layer and the second free layer.

According to one embodiment, a method of manufacturing a magnetic recording head includes forming a microwave oscillator to cover a main pole and a side shield and also to cross at least a part of a side gap between the main pole and the side shield, and lapping the main pole, the side shield and the microwave oscillator in a height direction while monitoring an electric resistance between the main pole and the side shield.

An apparatus includes a polarizer, a first free layer, a second free layer, and an antiferromagnetic (AF) coupling layer. The polarizer has a perpendicular magnetic anisotropy (PMA). The polarizer, the first free layer, the second free layer, and the AF coupling layer are included in a spin-torque oscillator (STO). The AF coupling layer is positioned between the first free layer and the second free layer.