Magnetic disk comprising a first carbon overcoat having a high SP3 content and a second carbon overcoat having a low SP3 content

A magnetic recording medium comprising:

• a substrate;
• a magnetic layer formed on said substrate;
• a first carbon layer formed on said magnetic layer, said first carbon layer comprising predominantly SP3 carbon;
• a second carbon layer formed on said first carbon layer, said second carbon layer comprising about 60% or less SP3 carbon, the SP3 content of said second carbon layer being less than the SP3 content of the first carbon layer;
• and
• a lubricant layer on said second carbon layer.

A magnetic recording medium comprising:

• a substrate;
• a magnetic layer formed on said substrate;
• a first carbon layer formed on said magnetic layer, said first carbon layer being formed by sputtering during which a voltage is applied to a sputtering target, said sputtering target comprising carbon, said voltage being applied by a power supply in the form of pulses, said pulses comprising at least a first portion and a second portion, the voltage applied during the second portion being more negative than that applied during the first portion, wherein a first sub-portion of said second portion is more negative than a second subportion of said second portion;
• a second carbon layer formed on said first carbon layer, said second carbon layer comprising about 600% or less SP3 carbon, the SP3 content of said second carbon layer being less than the SP3 content of the first carbon layer;
• and
• a lubricant layer on said second carbon layer.