The present invention provides a substrate for a magnetic recording medium in which bulges are not easily formed on a surface thereof by a physical impact in a size for a 2.5-inch type hard disk drive, 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, has a diameter of 54 to 70 mm, and a disk shape having a hole whose inner diameter ranges from 19 to 26 mm in the center thereof. 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 surface 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.

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 stack includes a substrate, a magnetic recording layer having a columnar structure, and an interlayer disposed between the substrate and the magnetic recording layer. The columnar structure includes magnetic grains separated by a crystalline segregant or a combination of crystalline and amorphous segregants.

A magnetic recording medium is described that includes a substrate and an amorphous soft underlayer (SUL). An NiPt seed layer is formed on the SUL where the Pt atoms have substitutionally replaced at least some of the Ni atoms within an Ni lattice structure of the NiPt to form a solid solution of NiPt. In some examples, the NiPt seed layer is formed of Ni.sub.40Pt.sub.60. An Ru interlayer is formed on the seed layer. In some examples, the NiPt seed layer has a lattice mismatch with the Ru interlayer of 0.4% or less. A magnetic recording layer is formed on the Ru interlayer. Additional layers or films may be provided. The medium may be configured for use with perpendicular magnetic recording (PMR). A data storage device that includes the magnetic recording medium is described. Methods for fabricating the magnetic recording medium are set forth herein as well.