We predict and experimentally demonstrate that in a medium with externally induced anisotropy, a wave source of a sufficiently small size can excite practically nondiffractive wave beams with stable ...subwavelength transverse aperture. The direction of beam propagation is controlled by rotating the induced anisotropy axis. Nondiffractive wave beam propagation, reflection, and scattering, as well as beam steering have been directly observed by optically probing dipolar spin waves in yttrium iron garnet films, where the uniaxial anisotropy was created by an in-plane bias magnetic field.
Microwave magnetization dynamics on two-dimensional periodic arrays of nanoscale magnetic antidots with magnetic field applied perpendicular to the lattice plane have been studied using ferromagnetic ...resonance spectroscopy. Linear dependence of the resonant mode frequency on the applied field was observed experimentally. Theoretical calculations show that this linear dependence originates from the high symmetry imposed by applying the field perpendicular to the plane of the antidot lattice. The calculated mode profiles exhibit a fourfold symmetry in contrast to the twofold symmetry typical for the in-plane magnetization direction. From the calculated Bloch wave dispersion the group velocities along the 10 and 11 directions and close to the center of the first Brillouin zone are found to be the same, which demonstrates a very high degree of isotropy of magnonic modes for the center of this zone in this case. Perpendicular standing spin-wave modes due to microwave shielding were also observed on the antidot lattices.
We demonstrate theoretically and confirm experimentally that nonlinear spin waves excited in thin yttrium iron garnet films are good candidates for squeezing vacuum quantum noise. The experimental ...demonstration is in the form of a measurement of spin-wave induced modulation instability (IMI) conducted in the classical regime. The experiment evidences strong phase locking of an idler wave parametrically generated in the film with a deterministic small-signal wave launched into the film from an external source. The theory predicts that the same behavior will be observed for vacuum quantum noise, resulting in squeezing of the noise.
We show experimentally and by numerical simulations that spin waves propagating in a magnetic film can pass through a region of a magnetic field inhomogeneity or they can be reflected by the region ...depending on the sign of the inhomogeneity. If the reflecting region is narrow enough, spin-wave tunneling takes place. We investigate the tunneling mechanism and demonstrate that it has a magnetic dipole origin.
We show both theoretically and experimentally that a collapsing (2+1)-dimensional wave packet in a medium with cubic nonlinearity and a two-dimensional dispersion of an order higher than parabolic ...irradiates untrapped dispersive waves. The studies are performed for a spin-wave bullet propagating in an in-plane magnetized ferrimagnetic film. An induced uniaxial anisotropy in such a medium leads to the formation of narrow spin-wave caustic beams whose angles to the bullet's propagation direction are modified by the motion of the source.
This Letter reports the first experimental demonstration of progressive chaos development through four-wave mixing of spin wave amplified harmonics in magnonic active-ring oscillators. We find that ...the route to chaos represents a sequence of quasiperiodic regimes of oscillations and ultimately yields formation of a 3D torus in the phase space. The transition from the quasiperiodic oscillations to chaos proceeds through progressive spectrum stochastization during which the amplified harmonics gradually disappear.
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