MICROMAGNETIC TRANSVERSE CORRELATION LENGTH IN THIN-FILM MAGNETIC RECORDING MEDIA, MEDIUM NOISE, AND TRACKING

We compare the cross correlation coefficient of signal and noise volta ges read on magnetic thin film rigid disks by a magnetic recording hea d at accurately controlled different lateral positions, and deduce fro m the results a transverse correlation length lambda which is a measur e of the characteristic lateral dimension of the magnetic microfeature s of the medium. By analyzing correlation data from uniformly magnetiz ed media and from media with saturated and unsaturated written transit ions we can determine lambda as a function of the medium's state of ma gnetization. Values of lambda inferred from our measurements on typica l media are less than 0.5 mu m, ranging down to several hundred angstr oms in some instances. We have applied the short correlation length as the basis for detecting and controlling lateral head displacements.