Influence of Periodic Patterning on the Magnetization Response of Micromagnetic Structures

The magnetization response of single, patterned, thin-film Permalloy (Ni_80Fe_20, Py) elements embedded in a coplanar waveguide (CPW) is investigated. The anisotropic magnetoresistance (AMR) effect serves as the detection mechanism in current-modulated differential resistance (dV/ dI) and rectification effect measurements, which reveal magnetization dynamics over a broad frequency range. Differently shaped Py elements had distinctly different magnetization responses. In rectangular Py elements, the dynamic low frequency response shows two resonant excitations, whereas multimode ferromagnetic resonance (FMR) occurs in the high frequency range. Disk-shaped patterning significantly increases the magnetic loss in comparison to simple rectangular elements.