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 mu-track model, jitter power sigma(2)(j) 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 s(c). A narrower reader may exhibit a nonlinear behavior in the sigma(2)(j) 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 mu-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 mu-track model.