A SIMPLIFIED MODEL OF HIGH-DENSITY TAPE-RECORDING

A simplified vector field model is used to analyze isolated pulse asym metry, input/output curves, nonlinearities in dibit recording, and ove rwrite for thick longitudinal tape. The recording layer of a well orie nted medium is discretized into laminae, and the magnetization transit ion parameter and phase in each lamina are determined by both the vect or head field and vector demagnetizing field. Typical head-medium spac ing is considered as well as imaging of the demagnetizing fields by th e record head. A significant magnetization transition phase shift and an increasing transition length with depth into the media are produced by the demagnetizing field, which plays a central role in explaining the phenomena of high density tape recording. Both pulse asymmetry and nonlinearities increase with demagnetizing ratio 4piM(r)/H(c). The si gnal voltage increases with bit length and decreases with the demagnet izing field in agreement with experiment. Overwrite for fixed frequenc y improves for larger deep gap field until the head field to coercivit y ratio H(g)/H(c) reaches 3.5 and then subsequently decreases, for typ ical head-medium spacing d/g = 0.25 and 4piM(r)/H(c) = 2. 2F/1F overwr ite maximizes when the bit length of the 2 F signal equals the gap len gth in agreement with measurement.