Geometric effects in the magnetic recording process

A simplified view of magnetic recording is presented in which the effect of head-medium geometry is clearly exhibited. The model is applied to contact recording with a ring head on thick particulate media. Demagnetization fields are neglected and identical particles with angularly invariant switching fields are considered with various orientation distributions in the recording plane. For all orientation distributions symmetric about the longitudinal direction the longitudinal magnetization component vanishes at the head surface and increases with depth into the medium. Conversely, the vertical component is maximum at the head surface and decreases with depth. The resulting recording spectra therefore have greater magnitudes for vertically well-oriented particles and isotropic distributions of particles with biaxial symmetry. At short wavelengths these distributions give approximately 5 dB more output than longitudinally well-oriented media. The depth variation of longitudinal magnetization also provides one explanation for the peak in the short wavelength input-output curve measured on longitudinal media. These conclusions are expected to be dependent on the assumed angular variation of the particle nucleation field.