A sputtering target according to the present invention contains Co and one or more metals selected from the group consisting of Cr and Ru, as metal components, wherein a molar ratio of the content of the one or more metals to the content of Co is or more, and wherein the sputtering target contains Nb.sub.2O.sub.5 as a metal oxide component.

A non-magnetic substrate for a magnetic disk includes a substrate main body having two opposing main surfaces, and a metal film that is provided on the main surfaces and is made of a material having a loss factor of 0.01 or more. The non-magnetic substrate has a thickness (T+D) of 0.700 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body and a thickness D of the metal film, and a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body is 0.025 or more.

A substrate for a magnetic disk includes a substrate main body having two main surfaces, and a film that is provided on the main surfaces and is made of a material having a loss factor of 0.1 or more. The substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and a thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy a relationship D0.0082/T0.0015.

A method of encoding information in an object that may allow for enhanced tailorability of the encoding during the processing and/or also enhance the amount of information encoded in the object. More particularly, the method of encoding the object enables the magnetic characteristics at different spatial locations of the object to be modified to form a spatial array of the different magnetic characteristics for representing the encoded information. The method can be used to permanently embed a magnetic signature in a non-magnetic object, for example. More specifically, the method allows different portions of the object to exhibit different magnetic characteristics at each spatial location of the object in three dimensions, and more particularly configuring the magnetic vectors of those portions in many possible orientations with a 4n steradian solid angle and/or with different intensities.

Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium. A magnetic recording medium includes a substrate, a heat sink layer on the substrate, and an underlayer on the heat sink layer. The underlayer includes an amount of an electrically conductive material between about 20 mole percent (mol %) and about 100 mol %. The magnetic recording medium further includes the plurality of magnetic recording layers on the underlayer. The plurality of magnetic recording layers includes a first magnetic recording layer that comprises FePtAgX, wherein X is an oxide.

Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium that has a magnetic recording layer on a magnesium oxide-titanium oxide (MTO) underlayer, where the MTO underlayer includes an additive material that chemically bonds with titanium. In some examples, the additive material includes iron-oxide, iron, carbon, or various aluminum oxides. By providing the additive material to the MTO that chemically bonds with the titanium of the MTO, diffusion of titanium from the MTO underlayer into the magnetic recording layer is mitigated to provide an improved recording layer that achieves improved areal densities. In some embodiments, an additional magnesium oxide-nitrogen underlayer is also provided, which may include more of the additive material.

Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium that has a magnetic recording layer on a magnesium oxide-titanium oxide (MTO) underlayer, where the MTO underlayer includes an additive material that chemically bonds with titanium. In some examples, the additive material includes iron-oxide, iron, carbon, or various aluminum oxides. By providing the additive material to the MTO that chemically bonds with the titanium of the MTO, diffusion of titanium from the MTO underlayer into the magnetic recording layer is mitigated to provide an improved recording layer that achieves improved areal densities. In some embodiments, an additional magnesium oxide-nitrogen underlayer is also provided, which may include more of the additive material.

A substrate for a magnetic disk includes a substrate main body having a disk shape and an alloy film. The substrate has a thickness (T+D) of 0.520 mm or less, which is the sum of a thickness T of the substrate main body and a thickness D of the film formed on main surfaces of the substrate main body. The disk shape has an outer diameter of 90 mm or more. A ratio D/T of the thickness D to the thickness T is 0.025 or more. The thickness of the film formed on an outer circumferential edge surface of the substrate main body is greater than the thickness of the film formed on each of the main surfaces, and the thickness of the film formed on each of the main surfaces is 80% or more of the thickness of the film formed on the outer circumferential edge surface.

Disclosed is a perpendicularly magnetized film structure using a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow, comprising a substrate of a cubic single crystal substrate having a (001) plane or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer formed on the substrate from a thin film of a metal having an hcp structure in which the [0001] direction of the thin metal film forms an angle in the range of 42? to 54? with respect to the <001> direction or the (001) orientation of the substrate; and a perpendicularly magnetized layer located on the metal underlayer and formed from a cubic material selected from a Co-based Heusler alloy and a cobalt-iron (CoFe) alloy having a bcc structure a constituent material, and grown to have the (001) plane.

A substrate for a magnetic disk has a disk shape. The substrate has a diameter D of 85 mm or more and a thickness T of 0.6 mm or less. When an impact is applied to the substrate under conditions of 70 (G) and 2 (msec) in a normal direction of main surfaces of the substrate in a state in which an inner circumferential end portion of the substrate is fixed, the maximum amplitude of vibration in a thickness direction of an outer circumferential end portion of the substrate is 0.25 mm or less, the substrate is a non-magnetic metal substrate, and regarding the Young's modulus E and the thickness T of the substrate, a value of E.Math.T.sup.3 is 3 to 18 (GPa.Math.mm.sup.3).