Angular dependence of switching field of magnetic recording particles

In a magnetic recording media, anisotropic particles are placed with different directions in the head field. The switching field, H(s) of a particle at a certain direction is defined as the minimum field, which reverses its easy axis magnetization. To determine the position of magnetization transition in recording media, one needs the angular dependence of the switching field. To find this for a texture of anisotropic single domain particles, the acicular iron particles with 0.3 mum length have been grown in a magnetic field. Then, the textures of the particles have been oriented by another magnetic field. We have measured the remanent magnetization of samples m(r)(theta) and m(r)(H), respectively, as functions of angle and field by a VSM system. The easy axis distribution is obtained from m(r)(theta), then the distribution and m(r)(H) is used for determining the angular dependence of the switching field. Results show that H(s) for small angles is <20% of the anisotropy field of the particles H(k). This difference from the Stoner-Wohlfarth model is explained by using particles interaction. (C) 2002 Elsevier Science B.V. All rights reserved.