The magnetocrystalline anisotropy of epitaxially grown bcc-Fe(001) films on GaAs(001) shows a transition from a fourfold intrinsic anisotropy in thick films to an uniaxial one in ultrathin films (<3 nm) and hence can be tuned by varying the film thickness. Here we investigate the consequence of such an anisotropy tuning for the magnetization configurations of nanomagnets. The thickness was varied between 2.5 and 30 nm in steps of 2.5 nm. Disks with diameters between 200 nm and 2 μm were patterned with electron beam lithography and ion beam etching. The remanent and ac-demagnetized states as well as the switching behavior were examined by magnetic force microscopy. In addition, we employed micromagnetic simulations to compare with the measured results.
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