Two-Dimensional Magnetic Recording With a Novel Write Precompensation Scheme for 2-D Nonlinear Transition Shift

This paper proposes a novel write precompensation scheme that adjusts the current magnitude, not the timing, to mitigate the serious 2-D nonlinear transition shift (NLTS) during the shingled writing process in a two-dimensional magnetic recording (TDMR) system. This scheme calculates the needed optimum write field for the current transition being written by subtracting the demagnetizing field produced by the previous written bits from a fixed write field and determines the optimum writing current based on the minimum mean-squared-error criterion between the needed field and the available fields within an established field library. Such a write precompensation scheme is tested with a micromagnetic writer and exchange coupled composite media, and readback with a rotated reader array combined with a read channel. Simulation indicates that the proposed write precompensation technique can decrease bit error rate compared with the case without write precompensation and approach the performance of a system with negligible NLTS. Correspondingly, the maximum user areal density is increased from 3.2 to 4.1 Tbits/in
$^{\mathrm {\mathbf {2}}}$
for a TDMR system with 8 nm Voronoi grains due to the proposed write precompensation.