Magnetic recording medium, method for producing the same, and magnetic recording apparatus

A magnetic recording medium comprising:

• a substrate;
• a first underlying layer which is formed on the substrate;
• a second underlying layer which is formed on the first underlying layer;
• and
• a magnetic layer which is formed on the second underlying layer and on which information is recorded, wherein:
• the second underlying layer is composed of crystal grains substantially formed of at least one oxide selected from the group consisting of cobalt oxide, chromium oxide, iron oxide, nickel oxide, and magnesium oxide, and a crystal grain boundary containing at least one oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide;
• and
• the first underlying layer serves as a layer to prevent the second underlying layer from initial growth.

A magnetic recording medium comprising:

• a substrate;
• an underlying layer which is formed on the substrate;
• a control layer which is formed on the underlying layer and which is formed of at least one selected from the group consisting of magnesium oxide, chromium alloy, and nickel alloy;
• and
• a magnetic layer which is formed on the control layer and on which information is recorded, wherein:
• the underlying layer is composed of crystal grains substantially formed of at least one oxide selected from the group consisting of cobalt oxide, chromium oxide, iron oxide, nickel oxide, and magnesium oxide, and a crystal grain boundary containing at least one oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide.

A magnetic recording medium comprising:

• a substrate;
• an underlying layer which is formed on the substrate;
• and
• a magnetic layer which is formed on the underlying layer and on which information is recorded, wherein:
• the underlying layer is composed of crystal grains and a crystal grain boundary which surrounds the respective crystal grains, the crystal grains being arranged in a honeycomb configuration;
• and
• the crystal grains protrude at a height of 3 to 20 nm from a surface of the underlying layer.

A magnetic recording medium comprising:

• a substrate;
• an underlying layer which is formed on the substrate;
• and
• a magnetic layer which is formed on the underlying layer, wherein:
• the underlying layer exhibits soft magnetization, and the underlying layer is composed of crystal grains substantially formed of at least one oxide selected from the group consisting of cobalt oxide, chromium oxide, iron oxide, nickel oxide, and magnesium oxide, and a crystal grain boundary containing at least one oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide.

A magnetic recording medium comprising:

• a substrate;
• an underlying layer which is formed on the substrate;
• and
• a magnetic layer which is formed on the underlying layer and which has an easily magnetized direction in a direction perpendicular to a substrate surface, wherein:
• the underlying layer is composed of crystal grains substantially formed of at least one oxide selected from the group consisting of cobalt oxide, chromium oxide, iron oxide, nickel oxide, and magnesium oxide, and a crystal grain boundary containing at least one oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide which surrounds the respective crystal grains.

A method for producing a magnetic recording medium comprising, on a substrate, a magnetic layer for recording information thereon and a protective layer, the method comprising:

• generating plasma by means of resonance absorption;
• allowing the generated plasma to collide with a target so that target particles are sputtered;
• and
• applying a bias voltage between the substrate and the target to introduce and deposit the sputtered target particles on the substrate, whereby forming at least one layer of the magnetic layer and the protective layer.

A method for producing a magnetic recording medium comprising, on a substrate, an underlying layer and a magnetic layer for recording information thereon, the method comprising:

• generating plasma by means of resonance absorption;
• allowing the generated plasma to collide with a target so that target particles are sputtered;
• and
• applying a bias voltage between the substrate and the target to introduce and deposit the sputtered target particles on the substrate, whereby forming the underlying layer.