A base for a magnetic recording medium, includes an aluminum alloy substrate, and a nickel alloy film provided on at least one principal surface of the aluminum alloy substrate. The nickel alloy film includes Mo in a range of 0.5 wt % to 3 wt %, P in a range of 11 wt % to 15 wt %, and Al in a range of 0.001 wt % to 0.1 wt %.

A base for a magnetic recording medium, includes an aluminum alloy substrate, and a nickel alloy film provided on at least one principal surface of the aluminum alloy substrate. The nickel alloy film includes Mo in a range of 0.5 wt % to 3 wt %, P in a range of 11 wt % to 15 wt %, and Fe in a range of 0.0001 wt % to 0.001 wt %.

Provided are a thin hard disk substrate that is scratch-resistant on the disk surface and wobbles less during rotation and a hard disk device including such a hard disk substrate. The hard disk substrate 1 includes an aluminum alloy substrate 2 having NiP plating films 3 on the surfaces. The aluminum alloy substrate 2 has the Vickers hardness of 60 Hv or more, the ratio between the thickness of the NiP plating films 3 and the thickness of the Al alloy substrate 2 is 3.8% or more, the Young's modulus of the hard disk substrate 1 is 74.6 GPa or more, and the Vickers hardness of the hard disk substrate 1 is 293 Hv or more.

A magnetic recording medium includes: a substrate; a recording layer; and a layer being provided between the substrate and the recording layer, the layer containing a superelastic body.

An object is to provide a magnetic recording medium having favorable crystal orientation characteristics and exhibiting a high SNR.

The present technology provides a magnetic recording medium having a layer structure including a recording layer, a ground layer, and a base layer in this order, in which the ground layer includes a first ground layer on the recording layer side and a second ground layer on the base layer side, the first ground layer contains a nonmagnetic oxide, the first ground layer has a thickness of 2 nm or more and 10 nm or less, and the second ground layer has a thickness of 40 nm or more. Furthermore, the present technology also provides a magnetic recording cartridge including the magnetic recording medium.

A base for a magnetic recording medium, includes an aluminum alloy substrate, and a nickel alloy film provided on at least one principal surface of the aluminum alloy substrate. The nickel alloy film includes Mo in a range of 0.5 wt % to 3 wt %, P in a range of 11 wt % to 15 wt %, and Al in a range of 0.001 wt % to 0.1 wt %.

A base for a magnetic recording medium, includes an aluminum alloy substrate, and a nickel alloy film provided on at least one principal surface of the aluminum alloy substrate. The nickel alloy film includes Mo in a range of 0.5 wt % to 3 wt %, P in a range of 11 wt % to 15 wt %, and Fe in a range of 0.0001 wt % to 0.001 wt %.

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.

The present invention provides a substrate for a magnetic recording medium in which bulges are hardly formed on a surface thereof by a physical impact in a size for a 3.5-inch type HDD, and a width of displacement caused by fluttering is small. The substrate for a magnetic recording medium includes an Al alloy substrate and a Ni alloy plating film formed on a surface of the Al alloy substrate, and has a diameter of 95 to 98 mm, a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof, a thickness of 0.48 to 0.64 mm, and a mass of 9.0 to 15.0 g. The Al alloy substrate has a Young's modulus (E) of 74 GPa or more, a density () of 2.75 g/cm.sup.3 or less, and a ratio (E/) of 27 or more between the Young's modulus (E) and the density (). The Ni alloy plating film has a thickness of 4 to 7 m, and when an indentation is formed by pressing a diamond indentor whose tip has a square pyramid shape against a surfaces of the Ni alloy plating film with a test force of 0.49 N for 10 seconds in a vertical direction, an average height of bulges generated around the indentation ranges from 10 to 50 nm.

What is provided is an aluminum alloy substrate for a magnetic recording medium which has high rigidity and an excellent plating properties. The aluminum alloy substrate for a magnetic recording medium has a constitution in which coarse grains whose average grain size is within a range that exceeds 2 m and is less than or equal to 20 m are dispersed, the average number of coarse grains per area of 0.042 mm.sup.2 is 100 or more, and a surface roughness Ra is less than or equal to 0.2 m.