Transformation of propagating spin-wave modes in microscopic waveguides with variable width

We have studied experimentally the propagation of spin waves in microscopic transversally magnetized permalloy stripe waveguides with variable width. Spatially resolved measurement based on the microfocus Brillouin light-scattering spectroscopy allowed a direct observation of transformations of propagating transverse spin-wave modes in the region of the width transition. Our experiments show that due to the variation in the internal demagnetizing fields caused by the width variation, an effective control of the spin-wave propagation can be achieved. In particular, a splitting of a spin-wave beam into two independent beams or preferred excitation of certain transverse spin-wave modes can be realized.