Samuele Fin

Magnetic microstructures in electrodeposited Fe1 − xGax thin films (15 ≤ x ≤ 22 at.%)

We have investigated the magnetic behavior of Fe1 − xGax (15 ≤ x ≤ 22 at.%) thin films grown by electrodeposition. The samples exhibit a texture although a rather small diffraction peak related to the (1 0 0) phase can also be observed. The layers do not present perpendicular magnetic anisotropy but magnetic hysteresis loops and magnetic force microscopy evidence a significant out-of-plane component for the magnetization. This component seems to increase for Ga contents around the 19 at.% value at which these alloys present a peak for the magnetostriction constant in the [1 0 0] direction. In this composition range, we have also observed an enhancement of the period of the magnetic structures. The experimental results indicate that the origin of the domain configuration is the presence of clusters with a (1 0 0) structural phase. The out-of-plane component of the magnetization seems to arise because of the compression of these nanoaggregates.

How finite sample dimensions affect the reversal process of magnetic dot arrays

We investigate the magnetization reversal of a magnetic dot array by means of magneto-optical Kerr effect and magnetic force microscopy measurements as well as micromagnetic simulations. We find that the finite dimensions of the dot array introduce a global configurational anisotropy that promotes state transitions first in dots near the sample boundaries. From there, the reversal process expands towards the sample body by means of collective magnetization processes originating in the magnetostatic coupling between the dots. These processes are characterized by transition avalanches and the formation of magnetization chains. These findings are important in the development of applications that rely on a robust control of dot magnetization states in dot arrays.

Magnetization reversal in magnetic dot arrays: Nearest-neighbor interactions and global configurational anisotropy

Various proposals for future magnetic memories, data processing devices, and sensors rely on a precise control of the magnetization ground state and magnetization reversal process in periodically patterned media. In finite dot arrays, such control is hampered by the magnetostatic interactions between the nanomagnets, leading to the non-uniform magnetization state distributions throughout the sample while reversing. In this paper, we evidence how during reversal typical geometric arrangements of dots in an identical magnetization state appear that originate in the dominance of either Global Configurational Anisotropy or Nearest-Neighbor Magnetostatic interactions, which depends on the fields at which the magnetization reversal sets in. Based on our findings, we propose design rules to obtain the uniform magnetization state distributions throughout the array, and also suggest future research directions to achieve non-uniform state distributions of interest, e.g., when aiming at guiding spin wave edge-modes ...