Magnetization reversal in epitaxial Fe nanowires on GaAs(110)

The anisotropy constants of epitaxial Fe films prepared on GaAs(110) are determined using ferromagnetic resonance. The films are structured into wires by employing electron-beam lithography with subsequent Argon-ion etching. Magnetoresistance measurements for wires with widths ranging from 250--2000 nm show the increasing influence of the shape anisotropy with decreasing wire widths. The magnetocrystalline anisotropy constants determined from these measurements agree well with the values obtained for the continuous films. These results are additionally confirmed by magnetic force microscopy measurements and micromagnetic simulations using the object oriented micromagnetic framework (OOMMF). We show that we are able to prepare wires with a remanent magnetization oriented perpendicular to their long axis due to the interplay of cubic and uniaxial in-plane magnetic anisotropies. Moreover, we can tune the effective easy axis by adjusting the width of the wires.