The external field sweep-rate dependence of the intrinsic switching field distribution in perpendicular recording media is investigated. We derive a scaling relationship for switching field distributions at different sweep-rates, which we then validate by means of large-scale kinetic Monte Carlo simulations based on interacting Stoner–Wohlfarth particles. After demonstrating the possible occurrence of large differences between switching field distributions at slow time scales of conventional magnetometry and very fast processes relevant in magnetic recording, we propose a technique for extrapolating between these very different sweep-rates.

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Derivation assumes (1) [ln(tif0)]1/2[ln(tif0)]1/2=[ln(tf0)]1/2, with the notation ti=t, and that ti is only weakly correlated with HK,i. This is reasonable because βi is proportional to HK,i and because of the anticorrelation nature the ratio HC,i/HK,i, which results in a sharply peaked probability distribution for ti centered around the mean t. (2) That the coercive field characterizes switching of the most typical particles in the medium, which is the case for magnetic recording materials, to allow neglecting higher order covariance terms. We also note, that equivalent equation holds for mean values HC,i, βi, and HK,i as long as the differences HC,i-HC and HK,i-HK are not too large and follow similar trends as a function of R.
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Note that t does not appear in the case of the Sharrock equation, which applies to different experimental procedures based on measuring the remanent coercivity.3,18 Note also, that it is easier to fit the inverted Eq. (3), i.e., after expressing R as a function of HC.
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