Magnetic Reversal by Mixed Modes in Two-Dimensional Hexagonal Array of Hollow Cobalt Nanospheres

Magnetization reversal in two-dimensional hexagonal arrays of cobalt hollow spheres occurs by mixed coherent and curling-vortex modes. Micromagnetic analysis was based on values of exchange, demagnetizing, and anisotropy energy. Arrays of 20 nm and 30 nm radius spheres were modeled, with sphere separations of 0, 2, and 4 nm, which controlled the dipolar interactions. The results demonstrate that solutions for magnetization reversal of single hollow spheres cannot be applied to arrays of hollow spheres.