Packing factor and coercivity in tapes: A Monte Carlo treatment

To investigate the variation of coercivity with packing factor p, a computer model was set up which represented an assembly of a given p, of aligned randomly packed particles. A central particle was represented by a chain of six spheres; the outer particles were taken to be cylinders carrying + and - poles and arranged to achieve a desired magnetization. The mean interaction field componentsh_{x}, h_{y}, h_{z}acting on each sphere, due to the 500 outer particles, were evaluated. The process was then repeated for a different configuration of the outer particles, and a table was prepared givingh_{x}, h_{y}, h_{z}for each sphere of each central particle for each of 50 configurations. There was no significant contribution from the boundaries of the assembly. The magnetization in each sphere was free to adopt any orientation specified by\theta(i), \varphi(i); i = 1 ... 6. For a particular applied field H, the energy of each of the 50 central particles considered was minimized, so giving the six values of θ and, therefore, the axial component of the magnetization. Good agreement with experiment was found forH_{c}(p), for0 \leq p \leq 0.4. The effects of magnetocrystalline anisotropy were taken into account.