Investigation of novel overcoat for ultra-high density recording media

Abstract

In the field of head-disk interface in hard disk drives, reduction of magnetic spacing has been a topic of significant interest. For 2 Tb/in2, the budget for media overcoat, lubricant, flying height and the slider overcoat would be roughly 1 nm each, which makes the task difficult for every researcher. From the recording media perspective, reduction of the carbon overcoat from the current thickness of 3 nm to 1 nm is a big challenge. It is very difficult to come up with materials or process techniques to meet this requirement. A novel hybrid magnetic overcoat suitable for ultra-high density recording has been proposed and studied. The top layer is a thin layer of carbon (about 1 nm) for the purpose of lubrication affinity, corrosion protection and hardness. The bottom layer is a thin magnetic oxide/nitride layer (about 4 nm) (example: CoCrPt:SiO2 sputtered with nitrogen in order to form Si nitride / Si oxide at the grain boundary) which helps as an overcoat and in reducing the magnetic spacing. Media prepared with such an overcoat showed a lower pulse width at half pulse height and better thermal stability. Improved corrosion inhibition property was also observed. These results indicate that Hy-MOC provides a possible ultra-thin overcoat system for ultra-high density media.