Abstract: According to one embodiment, a disk device includes a housing, a temperature sensor in the housing, a magnetic disk in the housing, a magnetic head disposed in the housing to be movable in a radial direction of the magnetic disk, the magnetic head including a write head, a read head, a first thermal actuator, and a second thermal actuator, a power supply circuit which supplies first power to the first thermal actuator and supplies second power to the second thermal actuator, and a controller configured to adjust a power ratio between the first power and the second power, based on at least one of a change in temperature inside the housing and a change in a radial position of the magnetic head in the radial direction.

Abstract: According to one embodiment, a disk device includes a housing, a plurality of magnetic recording media disposed in the housing in a multi-layered manner with intervals therebetween and a plurality of spacer rings, one of the spacer rings being disposed between each adjacent pair of the magnetic recording media. At least one of an uppermost magnetic recording medium and a lowermost magnetic recording medium includes a substrate having a rigidity higher than that of substrates of the other magnetic recording media, and one or more of the plurality of spacer rings is in contact with the magnetic recording media including the substrate having the higher rigidity, and has a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings.

Abstract: According to one embodiment, a disk device includes a housing, a plurality of magnetic recording media disposed in the housing in a multi-layered manner with intervals therebetween and a plurality of spacer rings each disposed between each adjacent pair of the magnetic recording media. At least one of an uppermost magnetic recording medium and a lowermost magnetic recording medium includes a substrate having a rigidity higher than that of substrates of the other magnetic recording media, and spacer rings brought into contact with the magnetic recording media with the substrate having the higher rigidity have a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head including an assist part to assist recording of data into the magnetic disk, a controller configured to control the recording of data by the magnetic head based on a recording condition, and a memory configured to record a first threshold value used to define that an assist element included in the assist part is in a deterioration condition. Furthermore, the controller detects the condition of the assist element, determines whether or not the recording condition is changed based on the detected condition and the first threshold value stored in the memory, and changes the recording condition based on the result of the determination.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head including an assist part to assist recording of data into the magnetic disk, a controller configured to control the recording of data by the magnetic head based on a recording condition, and a memory configured to record a first threshold value used to define that an assist element included in the assist part is in a deterioration condition. Furthermore, the controller detects the condition of the assist element, determines whether or not the recording condition is changed based on the detected condition and the first threshold value stored in the memory, and changes the recording condition based on the result of the determination.

Abstract: According to one embodiment, a magnetic recording medium includes a surface area including a pair of main surfaces and a side provided between the main surfaces, a recording area formed to carry out magnetic recording, a non-recording area other than the recording area and a contaminant collecting portion provided in at least a part of the surface area within the non-recording area and having a surface free energy higher than a surface free energy of the surface area within the recording area.