Magnetization Reversal in Hexagonal Nanomagnets

Magnetic nanostructures often exhibit interesting shape anisotropies, which may provide new possible applications, depending on the geometry and the magnetic material with its magnetocrystalline anisotropy. Comparing the pure magnetic materials iron, cobalt, and nickel, their anisotropy constants vary by approximately two orders of magnitude, allowing for testing the effect of superposing shape anisotropies with different magnetocrystalline anisotropies. Here we report on angle-dependent micromagnetic simulations of three different hexagonal-shaped nanomagnets, prepared from iron, cobalt, and nickel. While usual hysteresis loops, mostly without steps, are visible for nickel nanomagnets, cobalt results in a broad range of magnetization reversal processes with several steps which vary during repeated simulations due to variations of the anisotropy axes in different grains of the nanoparticles. Iron provides the best compromise between steps along the hysteresis loops which were proven to be correlated with stable intermediate states, usable for quaternary or higher-order storage devices, and reliable magnetization reversal processes even for sputtered samples with arbitrary anisotropy orientations in the single grains. Our examinations reveal that for nanomagnets on dimensions of a few hundred nanometers, iron is the ideal material not only for new magnetic data storage applications, but also for basic investigations of new and possibly technologically usable magnetization reversal processes.