Determination of average demagnetizing fields in longitudinal magnetic recording using nanosecond field pulses

Abstract

The demagnetizing field across bit transitions in longitudinal recording media is measured quantitatively as a function of linear density using a quasi static write/read tester. Bit transitions with varying linear densities in the range 500-600 flux changes per mm are recorded on CoCr10Ta4 media films. The media are deposited onto a coplanar waveguide structure, which is used to generate reversal field pulses of well-defined amplitude and 10 ns width to minimize thermally activated processes. The demagnetizing field is extracted from the measured reversal field, which is the sum of the external waveguide field and the internal, density-dependent demagnetizing field. The experimental results are qualitatively consistent with those predicted by a simple magnetostatic model that assumes finite transition widths. © 2000 American Institute of Physics.