Magnetic Coercivity of Infinite Hexagonal Array of Ellipsoids Chains

In the present work is present an alternative to calculate, by analytical considerations, the angular dependence of coercivity for an extensive (infinite) array of ellipsoid chains. Ellipsoids of Ni with semi-axis a = 15 nm and c = ea, were the basis of the present study with e = 1, 2, 4, 8, 16, and 32. The center to center ellipsoid’s distance (into the chain) was r = 2c, and the coercivity was calculated for different values of e and d as a function of the angle of application of external field, measured from the chain axis. The energetic contributions, for calculations, were the dipolar and Zeeman. Combinations of the chain’s packing factor with different ellipsoid’s aspect ratios were used for the calculation of anisotropy field, HA. A direct calculation of inter-ellipsoid interaction was performed assuming uniform reversion by using the Stoner-Wohlfarth model. The dipolar contribution corresponding to the inter-chain interaction was estimated according to experimental results obtained for Ni nanowires arrays with hexagonal spatial distribution. In order to evaluate the inter-chain interaction the distance (d) was set at 55, 60, and 65 nm. The combination of these geometric parameters results in great modifications of coercivity values. With some limitations, the work here is important for comparative studies with experimental results. The model results reproduce those obtained by micromagnetic simulation reported in previous works.