Dynamic configurational anisotropy in Ni80Fe20 antidot lattice with complex geometry

Abstract

Efficient tunability of spin-wave dynamics has been demonstrated in Ni80Fe20 diamond-shaped antidot lattices (DADLs) arranged in square and hexagonal symmetry using all-optical time-resolved magneto-optical Kerr effect (TRMOKE) microscope. A stark variation in the spin-wave spectra is obtained with the strength and orientation of the in-plane bias magnetic field. The spin-wave modes in the square lattice exhibit four-fold rotational anisotropy, which is in contrast to a strong six-fold rotational anisotropy superposed with a weak four-fold anisotropy observed in the hexagonal lattice. Micromagnetic simulations qualitatively reproduce the experimentally observed spin-wave modes and the simulated mode profiles reveal the presence of diverse genres of extended, pseudo extended and quantized standing spin-wave modes in these lattices. Additionally, some lower frequency localized edge modes are obtained for some specific bias field orientations due to the presence of demagnetizing fields at the sharp corners of the diamond antidots. The strong modifications of the demagnetizing regions, as well as the internal field strengths around the diamond-shaped antidots, can explain the observed variation of the spin-wave dynamics. These findings are important for potential applications of the DADLs in future magnonic devices, leading towards the development of on-chip microwave logic and communication systems.