Nanostructures Physics Division

We investigate dispersion relation of spin waves in a thin homogeneous permalloy film decorated with a periodic array of elliptically shaped permalloy dots and separated by a nonmagnetic Pt spacer. We demonstrate formation of the magnonic band structure for Damon-Eshbach waves propagating in a permalloy film with the band gaps opened at the Brillouin zone border and at smaller wave numbers, due to the Bragg interference and interaction of propagating waves of the continuous film with a standing resonant mode of the nanoellipses, respectively. We show that the predominant role in the formation of the magnonic band structure and opening band gaps is played by a vertical dynamic coupling between propagating waves and magnetization oscillations in the nanodots. The shape anisotropy of the permalloy nanodots allows us to control the spin wave dynamics through the switch between two states of the magnetization with respect to the underneath film magnetization.