The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which an AlFeSil abrasion value measured on a surface of the magnetic layer is 20 ?m or more and 50 ?m or less, and standard deviation a of the AlFeSil abrasion value obtained in a width direction of the surface of the magnetic layer is 5.0 ?m or less.

According to one embodiment, a magnetic recording medium includes a first magnetic region, a second magnetic region, and a third magnetic region. The second magnetic region is provided between the third magnetic region and the first magnetic region in a first direction from the third magnetic region to the first magnetic region. A first composition ratio of a first Pt atomic concentration in the first magnetic region to a first Co atomic concentration in the first magnetic region is higher than a second composition ratio of a second Pt atomic concentration in the second magnetic region to a second Co atomic concentration in the second magnetic region. A third composition ratio of a third Pt atom concentration in the third magnetic region to a third Co atom concentration in the third magnetic region is higher than the second composition ratio.

According to one embodiment, a magnetic recording medium includes a first magnetic region, a second magnetic region, and a third magnetic region. The second magnetic region is provided between the third magnetic region and the first magnetic region in a first direction from the third magnetic region to the first magnetic region. A first composition ratio of a first Pt atomic concentration in the first magnetic region to a first Co atomic concentration in the first magnetic region is higher than a second composition ratio of a second Pt atomic concentration in the second magnetic region to a second Co atomic concentration in the second magnetic region. A third composition ratio of a third Pt atom concentration in the third magnetic region to a third Co atom concentration in the third magnetic region is higher than the second composition ratio.

Embodiments described herein provide methods and apparatus for treating a magnetic substrate having an imprinted, oxygen-reactive mask formed thereon by implanting ions into a magnetically active surface of the magnetic substrate through the imprinted oxygen-reactive mask, wherein the ions do not reduce the oxygen reactivity of the mask, and removing the mask by exposing the substrate to an oxygen-containing plasma. The mask may be amorphous carbon, through which carbon-containing ions are implanted into the magnetically active surface. The carbon-containing ions, which may also contain hydrogen, may be formed by activating a mixture of hydrocarbon gas and hydrogen. A ratio of the hydrogen and the hydrocarbon gas may be selected or adjusted to control the ion implantation.

Embodiments described herein provide methods and apparatus for treating a magnetic substrate having an imprinted, oxygen-reactive mask formed thereon by implanting ions into a magnetically active surface of the magnetic substrate through the imprinted oxygen-reactive mask, wherein the ions do not reduce the oxygen reactivity of the mask, and removing the mask by exposing the substrate to an oxygen-containing plasma. The mask may be amorphous carbon, through which carbon-containing ions are implanted into the magnetically active surface. The carbon-containing ions, which may also contain hydrogen, may be formed by activating a mixture of hydrocarbon gas and hydrogen. A ratio of the hydrogen and the hydrocarbon gas may be selected or adjusted to control the ion implantation.

The present invention provides a method for manufacturing a glass substrate for a magnetic disk or the like according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods. In the present invention, by mirror-polishing (final finishing-polishing) the main surfaces of the glass substrate used in a magnetic disk, for example, using a polishing liquid containing organic-based particles made of a styrene-based resin, an acrylic resin, or a urethane-based resin, as polishing abrasive particles, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.

The present invention provides a method for manufacturing a glass substrate for a magnetic disk or the like according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods. In the present invention, by mirror-polishing (final finishing-polishing) the main surfaces of the glass substrate used in a magnetic disk, for example, using a polishing liquid containing organic-based particles made of a styrene-based resin, an acrylic resin, or a urethane-based resin, as polishing abrasive particles, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.

A magnetic device including: a magnetic reader; a magnetic writer; and a variable overcoat, the variable overcoat positioned over at least the magnetic reader and writer, the variable overcoat having an overcoat layer, the overcoat layer having a substantially constant thickness and material; and at least one disparate overcoat portion, the disparate overcoat portion having a different thickness, a different material, or both, than the overcoat layer.

A magnetic device including: a magnetic reader; a magnetic writer; and a variable overcoat, the variable overcoat positioned over at least the magnetic reader and writer, the variable overcoat having an overcoat layer, the overcoat layer having a substantially constant thickness and material; and at least one disparate overcoat portion, the disparate overcoat portion having a different thickness, a different material, or both, than the overcoat layer.

The magnetic tape includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which an AlFeSil abrasion value measured on a surface of the magnetic layer is 20 m or more and 50 m or less, and standard deviation a of the AlFeSil abrasion value obtained in a width direction of the surface of the magnetic layer is 5.0 m or less.