A magnetic recording medium includes a substrate; a lower base layer formed on the substrate; and a (001) oriented L1.sub.0 magnetic layer formed on the lower base layer and including a first magnetic layer formed on the lower base layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing C, and a second magnetic layer formed on the first magnetic layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing oxide or nitride, the second magnetic layer further containing one or more elements selected from a group consisting of Mg, Ni, Zn, Ge, Pd, Sn, Ag, Re, Au and Pb as an additive.

A magnetic-disk substrate has an average value of squares of inclinations that is 0.0025 or less, and a frequency at which squares of inclinations are 0.004 or more is 15% or less, in a case where samples of inclinations on a main surface are obtained at intervals of 10 nm. The main surface is configured to receive at least a magnetic recording layer thereon. The magnetic-disk substrate includes an outer circumferential end portion and an inner circumferential end portion, and the outer circumferential end portion and the inner circumferential end portion have chamfered portions.

A magnetic-disk substrate has an average value of squares of inclinations that is 0.0025 or less, and a frequency at which squares of inclinations are 0.004 or more is 15% or less, in a case where samples of inclinations on a main surface are obtained at intervals of 10 nm. The main surface is configured to receive at least a magnetic recording layer thereon. The magnetic-disk substrate includes an outer circumferential end portion and an inner circumferential end portion, and the outer circumferential end portion and the inner circumferential end portion have chamfered portions.

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.

A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or aluminum alloy.

A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or aluminum alloy.

According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, and a magnetic head including a first reproducing unit. The first reproducing unit includes a first magnetic field generator separated from the magnetic recording medium in a first direction, and a first stacked body. At least a portion of the first stacked body is provided between the magnetic recording medium and the first magnetic field generator in the first direction. The first stacked body includes a first magnetic layer, a second magnetic layer separated from the first magnetic layer in a second direction crossing the first direction, and a first intermediate layer provided between the first magnetic layer and the second magnetic layer. The first stacked body performs an operation of generating a first alternating magnetic field. The first magnetic field generator generates a first magnetic field.

A hard disk drive includes a base deck with a floor portion and a side wall portion. The floor portion extends between an upper surface and a bottom surface, and the side wall portion extends from the floor portion. A top cover is coupled to the base deck and includes a ceiling portion and a wall portion. The hard disk drive includes a weld that directly couples the wall portion of the top cover to the floor portion of the base deck.

A hard disk drive includes a base deck with a floor portion and a side wall portion. The floor portion extends between an upper surface and a bottom surface, and the side wall portion extends from the floor portion. A top cover is coupled to the base deck and includes a ceiling portion and a wall portion. The hard disk drive includes a weld that directly couples the wall portion of the top cover to the floor portion of the base deck.

A dummy substrate is formed with a disk-shaped glass substrate having a center hole, and a magnetic recording film on an outer circumferential surface along a thickness direction of the glass substrate and an inner circumferential surface of the center hole, and a surface roughness (Ra) of one surface and the other surface of the glass substrate is in a range of 0.2 nm or more and 100 nm or less.