Fringing fields from step transitions of longitudinal and perpendicular magnetization on finite tracks

Analytical expressions for fringing fields are derived and evaluated for several examples. It is shown that fields from perpendicular (H_x) and longitudinal (H_y) transitions exhibit similar behavior at track center but differ significantly at the track edges and off-track. Fourier analysis is used to obtain an effective spacing as a function of z for the conventional exponential spacing loss, exp(-kd ). For the longitudinal transition at all wavelengths, the effective spacing is approximately the distance from the track edge. For the perpendicular transition at short wavelengths, the effective spacing is approximately 1.5 times the distance from the track edge. This result indicates a more rapid decay of the field from the perpendicular transition at short wavelengths. The off-track H_y fields are found to have more long-wavelength components