High-speed switching in particulate magnetic recording media

The development of a fast pulsed field magnetometer which can produce pulsed magnetic fields of amplitude up to 450 Oe is described in detail. The pulse width can be adjusted from 0.8 ns upwards, with rise times of as little as 105 ps. The system has been used to examine switching speed limitations in materials commonly used in particulate recording media. Measurements of the remanence coercivity as a function of time down to 10(-9) s show that the analysis of magnetization reversal in terms of the high-energy-barrier approximation for the relaxation time is still valid. However, ii appears that the limiting factor for this analysis is when the product of the effective measurement time and the attempt frequency (t(eff)f(O)) approaches unity.