Rotated Read Head for High Density Heat-Assisted Shingled Magnetic Recording

Abstract

Heat-assisted magnetic recording (HAMR) is the most promising candidate for next generation data storage. Previous study suggests that user areal density in HAMR with composite media can reach up to 4.7 Tb/in2 [1]. On the other hand, shingled magnetic recording has been adopted to keep the growth in user areal density for current state-of-art perpendicular magnetic recording. In this work, Heat-assisted Shingled Magnetic Recording (HSMR) is studied. It is known that adjacent track erasure can degrade signal-to-noise ratio (SNR) in conventional HAMR especially when the number of adjacent track write increases [2]. In HSMR, since there will be only one adjacent track write due to the shingled-style writing, HSMR should have better performance than conventional HAMR under the same cross-track density. As a consequence of transition curvature in HAMR [3], the shape of the remaining track after shingled writing is a half arc (Fig. 1). Thus, the read head should also be rotated by a certain angle (θ) to capture the effect from the arc shape of the transition. Table 1 shows the SNR for different track pitch and rotation angle of the read head for a heat spot with peak temperature of 850 K and full width at half maximum (FWHM) of 30 nm. It can be seen that SNR is enhanced by around 1 dB if the read head is rotated an optimal amount. Bit error rate is then calculated with a 1-D equalizer and an improved Viterbi detector [4]. It is shown that for a three-read head arrays, the user areal density can approach up to 5 Tb/in2.