Unexpected Width of Minor Magnetic Hysteresis Loops in Nanostructures

We study the coercive fields and phase stability of magnetic nanostructures in hard axis loops and periodic rotational external magnetic fields over wide ranges of field amplitudes depending on the particle size and shape. For this purpose, we use a finite difference code with a gradient descent energy minimization algorithm. Our numerical simulations show that magnetic nanostructures can, in certain field amplitude regions, exhibit minor magnetic hysteresis loops with higher width than their major counterpart as well as variations in the coercive field for consecutive external field periods. The origin of the variations is chaotic behavior of the underlying magnetization processes leading to different residual domains after each field cycle.