Efficiently reducing transition curvature in heat-assisted magnetic recording with state-of-the-art write heads

摘要

The curvature of bit transitions on granular media is a serious problem forthe read-back process. We address this fundamental issue and propose apossibility to efficiently reduce transition curvatures with state-of-the-artheat-assisted magnetic recording (HAMR) heads. We compare footprints ofconventional with those of the proposed head design on different media,consisting of exchange coupled and single phase grains. Additionally, weinvestigate the impact of various recording parameters, like the full width athalf maximum (FWHM) of the applied heat pulse and the coercivity gradient nearthe write temperature of the recording grains. The footprints are calculatedwith a coarse grained model, based on the Landau-Lifshitz-Bloch (LLB) equation.The presented simulations show a transition curvature reduction of up to 40 %,in the case of a medium with exchange coupled grains and a heat pulse with aFWHM of 40 nm. We further give the reason for the straightening of the bittransitions, by means of basic considerations with regard to the effectiverecording time window (ERTW) of the write process. Besides the transitioncurvature reduction the proposed head design yields an improvement of thetransition jitter in both down-track and off-track direction.