Spectrum of the Ferromagnetic Resonance of a Lattice of Orthogonal Permalloy Microwaveguides

The ferromagnetic resonance spectrum at a frequency of ~9.85 GHz for an in-plane magnetized 2D square lattice with the unit cell parameter а ≈ 15 μm consisting of orthogonal microwaveguides with a width of w ≈ 5 μm on the basis of a permalloy film with thickness of d ≈ 90 nm has been experimentally and numerically investigated. It is shown that upon variation in the angle θ between the magnetic field direction and the unit cell axis, the total spectrum of spin-wave excitations of the lattice can be presented as a superposition of the spectra of separate permalloy microstrips magnetized at angles θ and π/2–θ and regions corresponding to the lattice nodes. It has been found that, in the case of magnetization along the lattice diagonal (θ ≈ 45о), excitations localized at the lattice nodes dominate in the spectrum, whereas, at θ ≈ 0 and 90°, the main contribution is made by excitations localized mainly on the microwaveguide segments between the lattice nodes; at θ ≈ 10°–13° and 18–20°, “repulsion” of absorption lines in the spectrum is observed.