Excitation and tailoring of diffractive spin-wave beams in NiFe using nonuniform microwave antennas

We experimentally demonstrate by time-resolved scanning magneto-optical Kerr microscopy the possibility to locally excite multiple spin-wave beams in the dipolar-dominated regime in metallic NiFe films. For this purpose we employ differently shaped nonuniform microwave antennas consisting of several coplanar waveguide sections different in size, thereby adapting an approach for the generation of spin-wave beams in the exchange-dominated regime suggested by Gruszecki et al. [Sci. Rep. 6, 22367 (2016)2045-232210.1038/srep22367]. The occurring spin-wave beams are diffractive and we show that the width of the beam and its widening as it propagates can be tailored by the shape and the length of the nonuniformity. Moreover, the propagation direction of the diffractive beams can be manipulated by changing the bias field direction.