Current disk drive products have an areal density of 6 Gbit/in2 and this denisty is increasing a rate of 60% per year, or doubling every 1.5 years. This increase in density is achieved partly by reducing the grain size in the current granular magentic media. Each bit is composed of several hundred grains and to keep the signal-to-noise constant as the density increases, the number of grains must remain approximately constant. Thus, the grain size must be reduced in order to increase the density. However, at some grain size, the grains will become so small so as to become "superparamagnetic." At this point, the magnetization direction is unstable to thermal fluctuations and the magnetization direction can spontaneously reverse. The information stored on such media will decay with time.

          Current Media

One solution to this problem is to make single grain magnetic bits. This eliminates the statistical noise associated with granular media and increases the domain size by a factor of several hundred. This can be done by patterning a thin magnetic into 50 nm or smaller sized islands, which corresponds to 64 Gbit/in2 or above. We are investigating two novel approaches to patterned media: stamping and ion beam patterning.
          
           Possible future media