Magnetic recording medium and a method of manufacturing the same

A magnetic recording system comprising:

• a flying magnetic head, and
• a medium comprising a nonmagnetic substrate, and at least an underlayer, magnetic recording layer, and a protective layer sequentially laminated on the nonmagnetic substrate, wherein
• the underlayer is composed of ruthenium or an alloy of mainly ruthenium and has an undulating structure formed on the surface of the underlayer with ridge lines of concentric circles which have a pitch in the range of 5 to 50 nm, the undulating structure being a sinusoidal waveform in which an angle between a plane of the nonmagnetic substrate and a line connecting a top and a bottom of the undulating structure in a cross sectional plane perpendicular to the ridge line is in a range of 10 to 60 degrees;
• the magnetic recording layer contains at least ferromagnetic crystal grains and a nonmagnetic component;
• magnetic dots composed of the crystal grains with a grain size not smaller than 4 nm in the magnetic recording layer are aligned on the ridge lines of the underlayer, each magnetic dot bearing one bit of record and each of the magnetic dots being separated from each other by the nonmagnetic component;
• with the proviso that superparamagnetic crystal grains on a bottom line of the undulating structure, if present, have a grain size less than 4 nm and do not exhibit magnetization.

A magnetic recording medium comprising a nonmagnetic substrate, and at least an underlayer, magnetic recording layer, and a protective layer sequentially laminated on the nonmagnetic substrate, wherein

• the underlayer is composed of ruthenium or an alloy of mainly ruthenium and has an undulating structure which has a sinusoidal waveform with ridge lines which have a pitch in the range of 5 to 50 nm, in which an angle between a plane of the nonmagnetic substrate and a line connecting a top and a bottom of the undulating structure in a cross sectional plane perpendicular to the ridge line is in a range of 10 to 60 degrees,
• the magnetic recording layer contains at least ferromagnetic crystal grains and a nonmagnetic component,
• magnetic dots composed of the crystal grains with a grain size not smaller than 4 nm in the magnetic recording layer are aligned on a surface of the underlayer along the ridge lines, and
• each of the magnetic dots is separated by the nonmagnetic component from each other.

A magnetic recording system comprising:

• a flying magnetic head, and
• a medium comprising a nonmagnetic substrate, and at least an underlayer, magnetic recording layer, and a protective layer sequentially laminated on the nonmagnetic substrate, wherein
• the underlayer is composed of ruthenium or an alloy of mainly ruthenium and has an undulating structure formed on the surface of the underlayer with ridge lines of concentric circles which have a pitch in the range of 5 to 50 nm, the undulating structure being a sinusoidal waveform in which an angle between a plane of the nonmagnetic substrate and a line connecting a top and a bottom of the undulating structure in a cross sectional plane perpendicular to the ridge line is in a range of 10 to 60 degrees;
• the magnetic recording layer contains at least ferromagnetic crystal grains and a nonmagnetic component;
• and
• magnetic dots composed of the crystal grains with a grain size not smaller than 4 nm in the magnetic recording layer are aligned on the ridge lines of the underlayer, each magnetic dot bearing one bit of record and each of the magnetic dots being separated from each other by the nonmagnetic component.