Dresden 2026 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 39: Poster Magnetism II

MA 39.8: Poster

Mittwoch, 11. März 2026, 18:00–21:00, P2

Mapping the Interaction Field in Artificial Spin Ices — •Brindaban Ojha, Matías P. Grassi, and Vassilios Kapaklis — Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden

Artificial spin ice (ASI) consists of lithographically patterned nanomagnet arrays that interact through dipolar coupling. Although these interactions can be tuned by adjusting nanomagnet dimensions, periodicity, and thickness, their detailed distribution and influence on magnetization reversal remain incompletely understood. We study square ASI structures with nanomagnet widths corresponding to aspect ratios (length/width) of 3 and 4.5, while keeping the length fixed at ~450 nm, and probe their interaction fields using First-Order Reversal Curve (FORC) analysis. ASI with an aspect ratio of 4.5 shows a single central peak in the FORC distribution, whereas the aspect-ratio-3 system displays both a central peak and an asymmetric `boomerang'-shaped feature. To understand these signatures, we perform micromagnetic simulations using MuMax. After relaxation from a random state, lower-aspect ratio ASI develops multidomain or vortex-like states, while higher-aspect-ratio ASI stabilizes in single-domain configurations due to enhanced shape anisotropy. The simulations confirm that the central FORC peak corresponds to single-domain switching in the higher-aspect ratio ASI, whereas the `boomerang' feature arises from an intermediate S-shaped reversal mode in the lower-aspect ratio system. These results demonstrate how geometry governs interaction-field distributions and reversal mechanisms in ASI.

Keywords: Magnetization Reversal; Dipolar Interactions; First-Order Reversal Curve (FORC); Micromagnetic Simulations; Artificial Spin Ice (ASI)