According to one embodiment, a disk device includes a disk-shaped recording medium, a base accommodating the recording medium, the base including a bottom wall, a sidewall on a peripheral portion of the bottom wall, and a rib on a part of an upper surface of the sidewall, a first cover on a part of the upper surface of the sidewall, and a second cover on a first surface of the rib and above the first cover. The rib includes a first region with a first width, a second region with a second width less than the first width, and the first surface with a fixed width around an entire circumference of the rib. The first region and the second region are located corresponding to a side portion of the recording medium.

A Spin Hall Effect (SHE) assisted magnetic recording device is disclosed wherein a SHE layer comprising a giant Spin Hall Angle material is formed between a main pole (MP) trailing side and trailing shield (TS) bottom surface. The SHE layer may contact one or both of the MP and TS, has a front side at the air bearing surface (ABS) or recessed therefrom, and a backside up to 80 nm from the ABS. Current (I.sub.SHE) is applied in a cross-track direction and synchronized with the write current. Depending on SHE layer placement, a transverse spin transfer torque is applied to one or both of a local MP magnetization at the MP trailing side and a local TS magnetization at the TS bottom surface thereby tilting the former to a direction that enhances the MP write field and tilting the latter to a direction that increases the TS return field.

According to one embodiment, a magnetic recording head includes a main magnetic pole which applies a recording magnetic field to a magnetic recording medium, an auxiliary magnetic pole which faces the main magnetic pole across a recording gap, a first magnetic bypass layer which is provided in a recording gap in a track direction, and a second magnetic bypass layer which is provided in the recording gap in the track direction and is arranged at a distance from the first magnetic bypass layer in a track width direction.

According to one embodiment, a magnetic disk device includes a magnetic disk, a recording head and a controller configured to control the recording head. The recording head includes a high-frequency oscillator disposed in a write gap formed between a main magnetic pole and a return magnetic pole, and a bias voltage application circuit configured to apply a bias voltage to the high-frequency oscillator. The controller includes a bias voltage controller configured to change a bias voltage to be applied to the high-frequency oscillator in accordance with a sampling frequency of data before the data is recorded on the magnetic disk by the recording head.

According to one embodiment, a magnetic head includes first and second magnetic poles, a conductive part, an element part, and first to fourth terminals. The conductive part is electrically insulated from the first and second magnetic poles. The first and second terminals are electrically connected to the conductive part. The element part is provided between the first and second magnetic poles and electrically connected to the first and second magnetic poles. The element part is conductive. The third terminal is electrically connected to the first magnetic pole. The fourth terminal is electrically connected to the second magnetic pole. A first magnetic pole temperature in a first state is higher than a second magnetic pole temperature of the second magnetic pole in the first state. A first current is supplied between the first and second terminals in the first state.

According to one embodiment, a magnetic head includes first and second magnetic poles, a conductive part, an element part, and first to fourth terminals. The conductive part is electrically insulated from the first and second magnetic poles. The first and second terminals are electrically connected to the conductive part. The element part is provided between the first and second magnetic poles and electrically connected to the first and second magnetic poles. The element part is conductive. The third terminal is electrically connected to the first magnetic pole. The fourth terminal is electrically connected to the second magnetic pole. A first magnetic pole temperature in a first state is higher than a second magnetic pole temperature of the second magnetic pole in the first state. A first current is supplied between the first and second terminals in the first state.

According to one embodiment, a magnetic head includes first and second magnetic poles, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer provided between the second magnetic pole and the first magnetic layer, a third magnetic layer provided between the second magnetic pole and the second magnetic layer, a fourth magnetic layer provided between the second magnetic pole and the third magnetic layer, a first non-magnetic layer provided between the first magnetic layer and the first magnetic pole, a second non-magnetic layer provided between the second and first magnetic layers, a third non-magnetic layer provided between the third and second magnetic layers, a fourth non-magnetic layer provided between the fourth magnetic layer and the third magnetic layer, and a fifth non-magnetic layer provided between the second magnetic pole and the fourth magnetic layer.

A thermally-assisted magnetic recording head includes a main pole, a plasmon generator and a heat sink. The main pole includes a first narrow portion and a first wide portion. The plasmon generator includes a second narrow portion and a second wide portion. The first narrow portion has a first side surface and a second side surface. The second narrow portion has a third side surface and a fourth side surface. The heat sink includes a first portion adjacent to the first side surface and the third side surface, and a second portion adjacent to the second side surface and the fourth side surface.

The presently disclosed technology teaches integrating disc drive electronics into a transducer head. Decreased electrical transit times and data processing times can be achieved by placing the electronics on or within the transducer head because electrical connections may be made physically shorter than in conventional systems. The electronics may include one or more of a control system circuit, a write driver, and/or a data buffer. The control system circuit generates a modified clock signal that has a fixed relation to phase and frequency of a bit-detected reference signal that corresponds to positions of patterned bits on the disc. The write driver writes outgoing data bits received from an external connection to off-head electronics directly to the writer synchronized with the modified clock signal. The data buffer stores and converts digital data bits sent from the off-head electronics to an analog signal that is synchronized with the modified clock signal.

According to one embodiment, a magnetic disk device including a disk, a head which reads data from the disk, a memory which records data, and a controller which includes a table, and records, at a first time point at which a read gate is open, a first area number of a first area of the table in which first information related to first data is recorded, a first serial number of the first data added when the read gate is open, and a first count value of the first data, in the first area.