Axial and azimuthal spin-wave eigenmodes in rolled-up permalloy stripes

We experimentally realized rolled-up permalloy stripes to form three-dimensional ring-like ferromagnetic structures. By means of microwave absorption spectroscopy, we find multiple resonances occurring above a demagnetization field threshold which depends on the ring's axial width. Our experimental data can be well modeled by assuming both axial and azimuthal spin-wave confinement. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3700809]