Optimisation of bit patterned media for 1 Tb/in²

Micromagnetic simulations were used to investigate the influence of patterned media geometry on the signal to noise ratio (SNR), adjacent track erasure and write margin for a target recording density of 1 Tb/in². For an ideal patterned medium the readback noise was a maximum when the read head was directly over the dots and a minimum at the transitions. The SNR improved for smaller dots due to the larger dot separation. However, the ideal media with the highest SNR were also the most susceptible to dispersions of dot size and position. Low temperature simulations suggest that large write margins are available; however, at room temperature the write margin can be much reduced. Increasing the rise time of the write head had a deleterious effect on the write margin and the write margin was zero for rise times of more than 0.45 ns. Nevertheless, error-free writing at 1 Tb/in² could be achieved using appropriate head geometries and material parameters.