Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a write head and a first and a second read head, and a controller configured to generate a correction value based on placement information on the write head and the first and the second read head, a first distance between the first read head and the second read head in a case where the first read head is placed at a first position of the disk, and a second distance between the first read head and the second read head in a case where the first read head is placed at the first position, and to correct positions of the heads based on the correction value in a case where first data written with the first read head placed at the first position is read.

Abstract: 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.

Abstract: According to one embodiment, a magnetic disk device conforming to perpendicular magnetic recording includes a magnetic disk, a recording head, and a controller. The head includes a main magnetic pole, a return magnetic pole, a recording coil, and a conductive member in which end surfaces are connected to opposed surfaces of a write gap which is opposed to a distal portion of the main magnetic pole and a distal portion of the return magnetic pole, and a resistance value varies. The controller applies a current to the recording coil to excite the magnetic flux in the recording operation, and applies a current at a constant voltage to the magnetic circuit via the comductive member.

Abstract: A magnetic recording apparatus includes a disk-shaped recording medium with a magnetic recording layer, and a recording head that magnetically writes data onto the magnetic recording layer and includes a main magnetic pole, a write shield facing the main magnetic pole and positioned with a writing gap disposed between the main magnetic pole and the write shield, and a magnetic flux control layer disposed inside the write gap between the main magnetic pole and the writing shield. The magnetic flux control layer includes a first layer including a first metal and contacting one of the main magnetic pole and the writing shield, a second control layer, and a third layer including a second metal and contacting the other one of the main magnetic pole and the writing shield. The second control layer includes a magnetic metal and contacts the first layer and the third layer.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a write head and a first and a second read head, and a controller configured to generate a correction value based on placement information on the write head and the first and the second read head, a first distance between the first read head and the second read head in a case where the first read head is placed at a first position of the disk, and a second distance between the first read head and the second read head in a case where the first read head is placed at the first position, and to correct positions of the heads based on the correction value in a case where first data written with the first

Abstract: A magnetic recording apparatus includes a disk-shaped recording medium with a magnetic recording layer, and a recording head that magnetically writes data onto the magnetic recording layer and includes a main magnetic pole, a write shield facing the main magnetic pole and positioned with a writing gap disposed between the main magnetic pole and the write shield, and a magnetic flux control layer disposed inside the write gap between the main magnetic pole and the writing shield. The magnetic flux control layer includes a first layer including a first metal and contacting one of the main magnetic pole and the writing shield, a second control layer, and a third layer including a second metal and contacting the other one of the main magnetic pole and the writing shield. The second control layer includes a magnetic metal and contacts the first layer and the third layer.

Abstract: According to one embodiment, a magnetic head includes a magnetic pole having a first surface, a first shield separated from the magnetic pole along the first surface, and a stacked body provided between the magnetic pole and the first shield. The stacked body includes a magnetic layer, and first and second conductive layers. The magnetic layer includes at least one selected from the group consisting of Fe, Co, and Ni. The first conductive layer contacts the magnetic pole and the magnetic layer, and is provided between the magnetic pole and the magnetic layer. The second conductive layer contacts the magnetic layer and the first shield, is provided between the magnetic layer and the first shield. The first shield has a first shield surface contacting the second conductive layer. A ratio of a length of the magnetic layer to a length of the first shield surface is 0.1 or more.

Abstract: According to one embodiment, a magnetic head includes a magnetic pole having a first surface, a first shield separated from the magnetic pole along the first surface, and a stacked body provided between the magnetic pole and the first shield. The stacked body includes a magnetic layer, and first and second conductive layers. The magnetic layer includes at least one selected from the group consisting of Fe, Co, and Ni. The first conductive layer contacts the magnetic pole and the magnetic layer, and is provided between the magnetic pole and the magnetic layer. The second conductive layer contacts the magnetic layer and the first shield, is provided between the magnetic layer and the first shield. The first shield has a first shield surface contacting the second conductive layer. A ratio of a length of the magnetic layer to a length of the first shield surface is 0.1 or more.

Abstract: A magnetic head includes a main magnetic pole, a write shield separated from the main magnetic pole by a write gap, a first side shield that is separated from the main magnetic pole by a first side gap, a second side shield that is separated from the main magnetic pole by a second side gap, a first layer that has a first magnetic relative permeability and is disposed in the write gap between the main magnetic pole and the write shield, and a second layer that has a second magnetic relative permeability and is disposed in the first side gap and the second side gap, wherein the first magnetic relative permeability is smaller than the second magnetic relative permeability.

Abstract: According to one embodiment, a magnetic disk device conforming to perpendicular magnetic recording includes a magnetic disk, a recording head, and a controller. The head includes a main magnetic pole, a return magnetic pole, a recording coil, and a conductive member in which end surfaces are connected to opposed surfaces of a write gap which is opposed to a distal portion of the main magnetic pole and a distal portion of the return magnetic pole, and a resistance value varies. The controller applies a current to the recording coil to excite the magnetic flux in the recording operation, and applies a current at a constant voltage to the magnetic circuit via the comductive member.

Abstract: According to one embodiment, a magnetic disk drive records and reproduces referential data and measures a referential characteristic value in a state in which supply of a STO voltage is stopped, executes control of reducing a temperature set value of a heater at a recording operation, based on the referential characteristic value, records and reproduces corrected data and measuring a corrected characteristic value in a state of supplying the STO voltage with a polarity opposite to a polarity at a general operation, while varying the temperature set value at a recording operation, compares the referential characteristic value with the corrected characteristic value and obtaining a difference, and corrects the temperature set value based on the difference.

Abstract: According to one embodiment, a magnetic head includes an air bearing surface, a first surface on which contact pads connected to elements are provided, a pair of second surfaces provided respectively with a connection terminal connected to the contact pad, a main pole with a distal end portion extending to the air bearing surface, a write shield opposing the distal end portion of the main pole with a write gap therebetween, and a high-frequency oscillator provided between the main pole and the write shield within the write gap and electrically connected to the main pole and the write shield. The high-frequency oscillator includes a spin injection layer and an oscillation layer, and at least the oscillation layer is recessed in a direction away from the air bearing surface.

Abstract: According to one embodiment, a magnetic head includes an air bearing surface, a first surface on which contact pads connected to elements are provided, a pair of second surfaces provided respectively with a connection terminal connected to the contact pad, a main pole with a distal end portion extending to the air bearing surface, a write shield opposing the distal end portion of the main pole with a write gap therebetween, and a high-frequency oscillator provided between the main pole and the write shield within the write gap and electrically connected to the main pole and the write shield. The high-frequency oscillator includes a spin injection layer and an oscillation layer, and at least the oscillation layer is recessed in a direction away from the air bearing surface.

Abstract: A magnetic disk device according to an embodiment includes a magnetic head including a write head with a high-frequency oscillator and a read head, a recording medium, a driving unit configured to moves the magnetic head on the recording medium, a measuring unit configured to obtain a first read signal with no current or a smaller current and a second read signal with a normal current supplied in the normal writing operation, a comparison unit configured to calculate comparative data indicating a comparison result between the first and second read signals, and a determination unit configured to determine an oscillation characteristic from the comparative data.

Abstract: A magnetic disk device according to an embodiment includes a magnetic head including a write head with a high-frequency oscillator and a read head, a recording medium, a driving unit configured to moves the magnetic head on the recording medium, a measuring unit configured to obtain a first read signal with no current or a smaller current and a second read signal with a normal current supplied in the normal writing operation, a comparison unit configured to calculate comparative data indicating a comparison result between the first and second read signals, and a determination unit configured to determine an oscillation characteristic from the comparative data.

Abstract: According to one embodiment, a disk storage apparatus includes a magnetic head, a detector, a calculator, and a decision module. The magnetic head has a high-frequency assisted element disposed close to a main magnetic pole that generates a recording magnetic field for perpendicular magnetic recording, the high-frequency assisted element applying a high-frequency magnetic field onto a magnetic disk during data recording. The detector detects an electrical resistance of the high-frequency assisted element. The calculator calculates time axis data indicative of a variation, on a time axis, in the electrical resistance value detected by the detector. The decision module determines whether the high-frequency assisted elements is malfunctioning based on the time axis data.

Abstract: According to one embodiment, a magnetic head includes a magnetic core including a main pole, and a return pole opposed to the main pole with a magnetic gap therebetween, and configured to return magnetic flux from the main pole and form a magnetic circuit in conjunction with the main pole, a coil configured to excite magnetic flux in the magnetic circuit, and a nonmagnetic electrically conductive layer formed by disposing only a nonmagnetic material in the magnetic gap between the return pole and an end portion of the main pole on the recording medium side, and configured to electrically connect the main pole and the return pole. The main pole, the nonmagnetic electrically conductive layer, and the return pole are configured to constitute a series electrical circuit.

Abstract: According to one embodiment, a disk storage apparatus includes a magnetic head and a controller. The controller determines at regular intervals whether a recording density of a write signal belongs to a low-density region or a high-density region with reference to a reference density. In addition, the controller relatively reduces a current to energize a high-frequency-assisted element at a timing of the low-density region to be less than a current of the high-density region, in accordance with the low-density region or the high-density region in recording the data.

Abstract: According to one embodiment, a disk storage apparatus includes a magnetic head, a detector, a calculator, and a decision module. The magnetic head has a high-frequency assisted element disposed close to a main magnetic pole that generates a recording magnetic field for perpendicular magnetic recording, the high-frequency assisted element applying a high-frequency magnetic field onto a magnetic disk during data recording. The detector detects an electrical resistance of the high-frequency assisted element. The calculator calculates time axis data indicative of a variation, on a time axis, in the electrical resistance value detected by the detector. The decision module determines whether the high-frequency assisted elements is malfunctioning based on the time axis data.

Abstract: According to one embodiment, a magnetic disk drive includes a magnetic disk to be subjected to perpendicular recording, a first pole core including a main pole configured to record signals on the magnetic disk, a first coil wound around the first pole core, a second pole core magnetically independent of the first pole core, tip ends of which are arranged on both sides of the main pole, a second coil wound around the second pole core, a read unit including an element configured to read data recorded on the magnetic disk, and a correction unit configured to correct a current phase difference between the first and second coils.