A microwave assisted magnetic recording (MAMR) write head includes a main pole and a trailing shield. A spin torque oscillator device is disposed between the main pole and the trailing shield. The spin torque oscillator device includes a free layer. A trailing shield hot seed layer is disposed between the spin torque oscillator device and the trailing shield. The trailing shield hot seed layer includes a magnetic material doped with a rare earth element. In certain embodiments, the trailing shield hot seed layer includes the rare earth element in an atomic percent content from about 2% to about 10% atomic percent. In certain embodiments, the trailing shield hot seed layer has an intrinsic damping from about 0.02 to about 0.2.

A microwave assisted magnetic recording (MAMR) write head includes a main pole and a trailing shield. A spin torque oscillator device is disposed between the main pole and the trailing shield. The spin torque oscillator device includes a free layer. A trailing shield hot seed layer is disposed between the spin torque oscillator device and the trailing shield. The trailing shield hot seed layer includes a magnetic material doped with a rare earth element. In certain embodiments, the trailing shield hot seed layer includes the rare earth element in an atomic percent content from about 2% to about 10% atomic percent. In certain embodiments, the trailing shield hot seed layer has an intrinsic damping from about 0.02 to about 0.2.

According to one embodiment, a magnetic recording device includes a magnetic head, a first circuit, and a second circuit. The magnetic head includes a magnetic pole, a first shield, a stacked body provided between the magnetic pole and the first shield, a first terminal electrically connected to the magnetic pole, a second terminal electrically connected to the first shield, and a coil. The first circuit is electrically connected to the first terminal and the second terminal. The second circuit is electrically connected to the coil. The first circuit performs at least a first operation. In the first operation, the first circuit supplies a first current to a current path between the first and second terminals when the second circuit supplies a recording current to the coil. The first current is smaller than a second current. The second current causes an electrical resistance of the current path to oscillate.

According to one embodiment, a magnetic disk device applies a bias voltage for measurement to a high frequency assist element according to a setting instruction of the bias voltage to measure a conduction current by in a recording head, calculates the resistance value in the supply path of the bias voltage from a relationship between the measured current and the bias voltage for measurement, and changes the bias voltage applied at the time of data recording based on the calculated resistance value.

According to one embodiment, a magnetic disk device applies a bias voltage for measurement to a high frequency assist element according to a setting instruction of the bias voltage to measure a conduction current by in a recording head, calculates the resistance value in the supply path of the bias voltage from a relationship between the measured current and the bias voltage for measurement, and changes the bias voltage applied at the time of data recording based on the calculated resistance value.

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.

A microwave assisted magnetic recording writer has a main pole (MP) with a write gap formed between the MP trailing side and a trailing shield, a side gap between each MP side and a side shield, and a leading gap between the MP leading side and a leading shield. A spin torque oscillator (STO) is formed in at least each side gap and recessed from the air bearing surface to reduce wear. Each STO has a flux guiding layer (FGL) with a magnetization that flips to a direction substantially opposite to the gap field when a current of sufficient density is applied from the adjacent shield towards the MP thereby forcing additional flux out of the MP at the ABS to enhance writability on a magnetic recording medium. Accordingly, the gap between the recessed STO and ABS is reduced to provide enhanced area density capability without sacrificing overwrite.

A microwave assisted magnetic recording writer has a main pole (MP) with a write gap formed between the MP trailing side and a trailing shield, a side gap between each MP side and a side shield, and a leading gap between the MP leading side and a leading shield. A spin torque oscillator (STO) is formed in at least each side gap and recessed from the air bearing surface to reduce wear. Each STO has a flux guiding layer (FGL) with a magnetization that flips to a direction substantially opposite to the gap field when a current of sufficient density is applied from the adjacent shield towards the MP thereby forcing additional flux out of the MP at the ABS to enhance writability on a magnetic recording medium. Accordingly, the gap between the recessed STO and ABS is reduced to provide enhanced area density capability without sacrificing overwrite.

According to one embodiment, a magnetic disk device applies a bias voltage for measurement to a high frequency assist element according to a setting instruction of the bias voltage to measure a conduction current by in a recording head, calculates the resistance value in the supply path of the bias voltage from a relationship between the measured current and the bias voltage for measurement, and changes the bias voltage applied at the time of data recording based on the calculated resistance value.