Jitter Analysis and Cross-Track Correlation Length Extraction Through Nonlinear Noise Scaling With Reader Width

Understanding and further reduction of transition jitter are extremely critical to future areal density increase in a magnetic recording system. From the μ-track model, jitter power σ_j² is directly proportional to the inverse of reader width W_r as long as W_r is much greater than the cross-track correlation length sc. A narrower reader may exhibit a nonlinear behavior in the σ_j² versus 1/W_r plot, and this nonlinearity reveals the essential information needed for developing a novel s_c extraction scheme. The concept is first verified with the μ-magnetics model and then validated with experimental data. Recording measurement of jitter dependence on W_r is greatly simplified by performing subtraction of two off-track waveforms using a nominal width reader. This analysis has been applied to media series with different grain exchange couplings and grain sizes (GSs) to understand the jitter impact from s_c, GS, switching field distribution, and head field gradient. Fundamental media parametrics can be experimentally characterized and related to transition jitter through the revised μ-track model.