Estimation of submicron read-width in longitudinal magnetic recording

Low signal-to-noise ratios at submicron read-widths is a limiting factor in measurements of the magnetic read-width from a single microtrack. Instead, a number of adjacent microtracks, of decreasing widths were used to generate a series of microtrack profiles. There was a quadratic dependence of the full-width at half-maximum of the cross-track profile on the microtrack width. This result was also proved analytically for profiles with a Gaussian and Lorentzian shapes. The asymptotic limit of the quadratic fit yielded the magnetic width of the reader. A further improvement in the characterization method was possible by assuming that the microtracks had sharp edges. With a rectangular profile for the magnetization from the track, the area under the microtrack profile became proportional to the width of the track on the media. A least squares fit of profile width versus area was used to estimate read-width. The method was relatively insensitive to position errors on the spin-stand.