Angular dependence of magnetization reversal process in patterned Co thin films

We measured longitudinal and transverse magnetooptic Kerr effect loops to understand the angular dependence of magnetization reversal in an array of 5 μm × 25 μm rectangular thin Co bars with uniaxial anisotropy. When the magnetic field is applied close to the hard axis, the reversal is dominated by coherent rotation; when the field is applied close to the easy axis, the reversal is caused by domain-wall unpinning and the coercive fields observe the relation H_c = H₀/cos θ₀. For the other orientations, the magnetization first rotates smoothly at larger fields and then switches irreversibly by domain-wall unpinning.