Optimization of Layer Thicknesses for Dual-Layer Bit-Patterned Media Recording (BPMR) Systems

To increase the areal recording density of magnetic recording, we have investigated the effect of the thicknesses of the individual layers in dual-layer bit-patterned magnetic recording (BPMR) systems. The recording media consisted of two, discrete recording layers, separated by a non-magnetic spacer layer. The bottom recording layer thickness and head-medium spacing (HMS) were fixed, while the top recording layer thickness was varied to adjust the spacing between the reader and the bottom layer. By varying the layer thicknesses, the readback signal strengths from the top and bottom layers can be adjusted and balanced. To determine the bit-errorrate improvement needed to reach a target areal density of 4.0 Tbits/in2, i.e. 2.0 Tbits/in2 per layer, the readback signal was processed using an iterative method. The results showed that the proposed design could outperform a single-layer BPMR system.