Caustics are intricate and challenging to control near-field interference patterns that exist in a wide range of physical systems, and which usually exhibit a reciprocal wave propagation. Here, we utilize the highly anisotropic dispersion and inherent nonreciprocity of a magnonic system to shape nonreciprocal emission of causticlike spin wave beams in an extended yttrium iron garnet (YIG) film from a nanoconstricted waveguide. We introduce a near-field diffraction model to study spin-wave beam forming in homogeneous in-plane magnetized thin films, and reveal the propagation of nonreciprocal spin-wave beams directly emitted from the nanoconstriction by spatially resolved microfocused Brillouin light spectroscopy. The experimental results agree well with both micromagnetic simulation, and the near-field diffraction model. The proposed method can be readily implemented to study spin-wave interference at the sub-µm scale, which is central to the development of wave-based computing applications and magnonic devices.

Close

PrevNext

View figure in article

• Beam control
• Micromagnetism
• Nanoantennas
• Spin dynamics
• Spin waves
• Brillouin scattering & spectroscopy
• Linear spin wave theory