68 research outputs found
Wannier-Stark ladder spectrum of Bloch oscillations of magneto-dipole spin waves in graded 1D magnonic crystals
This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this recordWe have used the method of Wannier functions to calculate the frequencies and profiles of spin
waves localised in one-dimensional (1D) magnonic crystals due to a gradient in the bias magnetic
field. This localisation of spin waves is analogous to the phenomenon of Bloch oscillations of
quantum-mechanical electrons in crystals in a uniform electric field. As a convenient yet realistic
model, we consider backward volume magnetostatic spin waves (BVMSWs) in a film of yttriumiron garnet (YIG) in a bias magnetic field comprising spatially uniform, cosine and gradient
contributions. The spin-wave spectrum is shown to have the characteristic form of a WannierStark ladder. The analytical results are verified using those obtained using numerical
micromagnetic simulations. The physics of spin-wave Bloch oscillations combines the topics of
magnonic crystals and graded magnonic index – the two cornerstones of modern magnonics.Engineering and Physical Sciences Research Council (EPSRC)European Union Horizon 202
Towards graded-index magnonics: Steering spin waves in magnonic networks
Magnonics explores precessional excitations of ordered spins in magnetic materials—so-called spin waves—and their use as information and signal carriers within networks of magnonic waveguides. Here, we demonstrate that the nonuniformity of the internal magnetic field and magnetization inherent to magnetic structures creates a medium of graded refractive index for propagating magnetostatic waves and can be used to steer their propagation. The character of the nonuniformity can be tuned and potentially programmed using the applied magnetic field, which opens exciting prospects for the field of graded-index magnonics
Resonant scattering of spin waves from a region of inhomogeneous magnetic field in a ferromagnetic film
The transmission of a dipole-dominated spin wave in a ferromagnetic film
through a localised inhomogeneity in the form of a magnetic field produced by a
dc current through a wire placed on the film surface was studied experimentally
and theoretically. It was shown that the amplitude and phase of the transmitted
wave can be simultaneously affected by the current induced field, a feature
that will be relevant for logic based on spin wave transport.
The direction of the current creates either a barrier or well for spin wave
transmission. The main observation is that the current dependence of the
amplitude of the spin wave transmitted through the well inhomogeneity is
non-monotonic. The dependence has a minimum and an additional maximum. A theory
was constructed to clarify the nature of the maximum. It shows that the
transmission of spin waves through the inhomogeneity can be considered as a
scattering process and that the additional maximum is a scattering resonance
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