Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Yasushi Sakai

Hiroyuki Uwazumi

Shunji Takenoiri

Sadayuki Watanabe

Tadaaki Oikawa

Miyabi Nakamura

Toyoji Ataka

Kazuo Enomoto

Akira Sato

Norihiko Nakajima

Sadayuki Watanbe

Mitsuo Masuda

A perpendicular magnetic recording medium includes a nonmagnetic substrate, and a soft magnetic layer, a first orientation control layer, a second orientation control layer, a nonmagnetic intermediate layer, a magnetic recording layer, and a protective layer layered sequentially on the nonmagnetic substrate. The first orientation control layer includes a thin film having a face-centered cubic (fcc) structure. The magnetic recording layer includes a thin film layer having ferromagnetic crystal grains and nonmagnetic grain boundaries surrounding the ferromagnetic crystal grains, the ferromagnetic crystal grains including a CoPt alloy having ferromagnetic properties, and the nonmagnetic grain boundaries including an oxide or a nitride. The nonmagnetic intermediate layer includes a thin film containing Ru. The second orientation control layer includes an alloy thin film having an element selected from among Ni and Fe and having the fcc structure, the second orientation control layer having a saturation magnetic flux density Bs of 1 T or lower.

Perpendicular magnetic recording medium

A perpendicular magnetic recording medium, which includes a first magnetic recording layer, a second magnetic recording layer, and a third magnetic recording layer disposed sequentially on a nonmagnetic substrate, and a coupling layer formed between the first and second magnetic recording layers. The first, second and third magnetic recording layers have an easy axis of magnetization in a direction perpendicular to a film plane of the nonmagnetic substrate. The first and second magnetic recording layers are ferromagnetically coupled via the coupling layer.

A perpendicular magnetic recording medium is disclosed that achieves improved recordability without deteriorating thermal stability by reducing the switching field. A perpendicular magnetic recording medium of the invention has a first magnetic recording layer and a second magnetic recording layer between with is interposed a coupling layer that ferromagnetically couples the two layers. The first and second magnetic recording layers satisfy an inequality KuT&#x3e;KuTin the case where Hk&#x3e;Hkand an inequality KuT&#x3c;KuTin the case where Hk&#x3c;Hk, where Hkand Hkare anisotropy magnetic fields, Kuand Kuare uniaxial anisotropy constants, and Tand Tare thicknesses of the first magnetic recording layer and the second recording layer, respectively. An exchange coupling energy between the magnetic recording layers is preferably at least 5&#xd7;10erg/cm. Advantageously, the coupling layer is mainly composed of a material selected from V, Cr, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Ta, W, Re, and Ir, and has a thickness of at most 2 nm. At least one of the magnetic recording layers preferably has a granular structure.

The quantity of oxide contained in a magnetic layer is controlled to control the crystal grains and the segregation structure for ensuring low noise characteristic in a granular magnetic layer of a perpendicular magnetic recording medium. The granular magnetic layer consists of ferromagnetic crystal grains and a nonmagnetic grain boundary region mainly of an oxide surrounding the ferromagnetic crystal grains. The perpendicular magnetic recording medium has a nonmagnetic underlayer composed of a metal or alloy having hexagonal closest-packed crystal structure. The ferromagnetic crystal grain is composed of an alloy containing at least cobalt and platinum. The volume proportion of the nonmagnetic grain boundary region mainly of the oxide falls within a range of 15% to 40% of the volume of the total magnetic layer.

Perpendicular magnetic recording medium and method of manufacturing the same and product thereof

A perpendicular magnetic recording medium is disclosed in which each magnetic crystal grain in the magnetic recording layer has a multilayer structure and has a configuration like a truncated cone shape, in which the crystal grain of the final layer deposited in the film surface side at the final stage is smaller than the diameter of the crystal grain in the initial layer deposited on the substrate side at the initial stage. The invention improves S/N (signal output to noise ratio) by enhancing signal output and reducing noises. The medium is produced by a simple manufacturing method suitable for mass production, and provides a medium of high recording density by improving recording resolution.

Perpendicular magnetic recording medium and method for manufacturing same

A perpendicular magnetic recording medium, which includes a nonmagnetic substrate, and a soft magnetic layer, a first orientation control layer, a nonmagnetic intermediate layer, and a perpendicular magnetic recording layer formed sequentially on the nonmagnetic substrate. The perpendicular magnetic recording medium further includes a second orientation control layer provided between the first orientation control layer and the nonmagnetic intermediate layer. The nonmagnetic intermediate layer has hexagonal close-packed (hcp) structure. The first orientation control layer has a face-centered cubic (fcc) structure. The second orientation control layer includes Co and Cr, and has the hcp structure.

A perpendicular magnetic recording medium includes a soft magnetic backing layer, an underlayer, a nonmagnetic intermediate layer, and a magnetic recording layer sequentially deposited on a nonmagnetic substrate. The underlayer can contain cobalt, nickel, and iron and have an fcc structure and exhibit soft magnetic property. The underlayer preferably contains nickel in a range of 30 to 88 at % and iron in a range of 0.1 to 22 at %. The underlayer can further contain Si, B, Nb, N, Ta, Al, Pd, Cr, or Mo. The nonmagnetic intermediate layer preferably contains at least one element selected from Ru, Re, Pd, Ir, Pt, and Rh. The magnetic recording layer preferably has a granular structure. A seed layer can be further provided between the soft magnetic backing layer and the underlayer.

Perpendicular magnetic recording medium and the method of manufacturing the same

A perpendicular magnetic recording medium composed of a nonmagnetic substrate having a surface onto which are provided a plurality of layers including, in the order recited, a soft underlayer; a nonmagnetic coupling layer; a hard magnetic pinning layer which is antiferromagnetically coupled to the soft underlayer at ambient temperature via the nonmagnetic coupling layer and which has an axis of easy magnetization which extends in a direction which is perpendicular to that of the surface of the nonmagnetic substrate; a nonmagnetic intermediate layer; and a magnetic recording layer. Such a perpendicular magnetic recording medium has an improved medium performance, with reduced noise originating from the presence of the soft underlayer, and no erasure of recorded magnetization when influenced by an external magnetic field.

A perpendicular magnetic recording medium has a granular magnetic layer and a nonmagnetic underlayer of a metal or an alloy having a hexagonal close packed (hcp) crystal structure. A seed layer of a metal or an alloy of a face-centered cubic (fcc) crystal structure is provided under the nonmagnetic underlayer. Such a perpendicular magnetic recording medium exhibits excellent magnetic characteristics even when the thickness of the underlayer or the total thickness of the underlayer and the seed layer is very thin. Excellent magnetic characteristics can be obtained even when of the substrate is not preheated. Accordingly, a nonmagnetic substrate, such as a plastic resin can be employed to reduce the manufacturing cost.

Perpendicular magnetic recording medium and a method of manufacturing the same

A perpendicular magnetic recording medium and method thereof, includes a nonmagnetic substrate; a soft magnetic under layer; an intermediate layer; a bilayer magnetic recording layer; a protective layer; and a liquid lubricant layer. According to a following order, the soft magnetic under layer, the intermediate layer, the bilayer magnetic recording layer, the protective layer, and the liquid lubricant layer are sequentially stacked on the nonmagnetic substrate. The bilayer magnetic recording layer includes a first magnetic layer including a CoCr alloy crystalline film, and a second magnetic layer including a rare earth-transition metal alloy noncrystalline film.

Fabrication method for perpendicular magnetic recording media

A perpendicular magnetic recording medium includes a nonmagnetic substrate; a first underlayer provided on the nonmagnetic substrate; a first nonmagnetic intermediate layer provided on the first underlayer; a second underlayer provided on the first nonmagnetic intermediate layer; a second nonmagnetic intermediate layer provided on the second underlayer; and a magnetic recording layer provided on the second nonmagnetic intermediate layer, wherein the first underlayer comprises a soft magnetic material which has a face-centered cubic structure and which includes at least Ni and Fe, and wherein the second underlayer comprises a soft magnetic material which has a face-centered cubic structure and which includes at least Co. The orientation dispersion is reduced and crystal grain diameters are smaller in the magnetic recording layer, and the film thickness of nonmagnetic intermediate layers can be decreased so that performance improvements such as reduced noise, increased S/N ratio, and improved write-ability are achieved.

A perpendicular medium is disclosed in which an isolation structure of an underlayer is formed using a simple method as in a conventional manufacturing process for a medium of continuous films. The method suppresses dispersion of alignment and reduced magnetic cluster size in a magnetic recording layer. The perpendicular medium exhibits high recording density owing to thin film thickness of the underlayer. A perpendicular magnetic recording medium includes at least an underlayer and a magnetic recording layer sequentially laminated on a nonmagnetic substrate. The underlayer consists of crystal grains and an amorphous grain boundary, and the crystal grain has a shape holding a relation (an area of a bottom region at an initial stage of growth)&#x3e;(an area of a top region).

Perpendicular magnetic recording medium, method of manufacturing same, and magnetic recording device

A method of manufacturing a magnetic recording media includes a magnetic recording layer of a granular magnetic layer that has ferromagnetic crystal grains and an oxide nonmagnetic grain boundary or a nitride nonmagnetic grain boundary surrounding the ferromagnetic crystal grains. It further has an overcoating layer on the granular magnetic recording layer. The overcoating layer contains a nonmagnetic metal or a nonmagnetic alloy that can be diffused into the nonmagnetic grain boundary. The atoms coated on the granular magnetic recording layer diffuse into the nonmagnetic grain boundary even without being annealed, and promote to isolate the ferromagnetic crystal grains from each other. The overcoating can be removed after its formation to reduce the magnetic gap between the magnetic recording layer and the magnetic recording head.

Magnetic recording medium and the method of manufacturing the same

A substrate for a perpendicular magnetic recording medium has a soft magnetic underlayer that functions as a soft magnetic backing layer of a perpendicular magnetic recording medium. The substrate for a perpendicular magnetic recording medium has a nonmagnetic base made of Al&#x2014;Mg alloy or the like. The soft magnetic underlayer is formed of a Ni&#x2014;P alloy containing phosphorus in a range of 0.5 wt % to 6 wt % formed by electroless plating on the nonmagnetic base. The substrate can also include a nonmagnetic underlayer formed by electroless plating on the base before electroless plating the soft magnetic underlayer. To form the perpendicular magnetic recording medium, the surface of the soft magnetic is textured using free abrasive grains. Thereafter, a nonmagnetic seed layer, a magnetic recording layer, and a protective layer can be formed by sputtering. A soft magnetic supplemental layer also can be formed on the soft magnetic underlayer before forming the seed layer.

Substrate for a perpendicular magnetic recording medium, perpendicular magnetic recording medium, and manufacturing methods thereof

A perpendicular magnetic recording medium is disclosed that is characterized by a lowered noise component and improved thermal stability. The method for making the recording medium includes the serial steps of forming a soft magnetic back-lining layer on a non-magnetic substrate, forming an intermediate layer on the soft magnetic back-lining layer, forming a magnetic recording layer on the intermediate layer, and forming a protective film and then a liquid lubricating layer on the magnetic recording layer. Thermal treatment is executed after the formation of the magnetic recording layer and before the formation of the protective film, or after the formation of the protective film and before the formation of the liquid lubricating layer. The thermal-processing steps are is executed in a vacuum higher than about 0.1 Pa and in a thermal environment within a range from about 200&#xb0; C. to about 250&#xb0; C. for a period of less than about 60 seconds.

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Nagano, Japan

Yasushi Sakai