Dependence of Bit Error Rates on HAMR Transition Curvatures

Transition curvature limits the performance of heat-assisted magnetic recording (HAMR), especially when bit length (BL) is reduced below 10 nm. In this article, in order to quantify this issue, the dependence of signal-to-noise ratios (SNRs) and bit error rates (BERs) on HAMR transition curvatures is investigated utilizing previously obtained curvature values. An artificial recording method is used and a Viterbi algorithm is applied to decode the readback signals and calculate BERs. A pseudorandom binary sequence (PRBS) is used. Two BLs are tested: 7.5 and 8.5 nm. Different reader widths (RWs), shield-to-shield distances, and magnetic fly heights are studied in order to seek optimized reader configurations. Generally, transition curvatures have a negative effect on SNR and BER performance, but this effect can be mitigated by the reduction of certain reader dimensions.