Evidence of Fano-like resonances in mono-mode magnetic circuits

Abstract

In the frame of long-wavelength Heisenberg model, a simple magnonic device is designed to obtain possibly transmission stop bands ͑where the propagation of spin waves is forbidden͒. This simple device is composed of an infinite one-dimensional mono-mode waveguide ͑the backbone͒ along which N͑NЈ͒ side resonators are grafted at two sites. Contrary to all known systems of this kind, a spectral transmission gap of nonzero width occurs here even with this simple structure. This is obtained by combining appropriately the zeros of transmission of the side resonators. Sharp resonant states inside the gaps can be achieved without introducing any defects in the structure. This results from an internal resonance of the structure when such a resonance is situated in the vicinity of a zero of transmission or placed between two zeros of transmission, the so-called Fano resonances. A general analytical expression for the transmission coefficient is given for various systems of this kind within the framework of the Green's function method. The amplitude, the phase, and the phase time of the transmission are discussed as a function of frequency and it is shown that the width of the stop bands is very sensitive to the number of the side resonators. These results should have important consequences for designing integrated devices such as narrow-frequency optical or microwave filters and high-speed switches.

Graded Magnonic Index and Spin Wave Fano Resonances in Magnetic Structures: Excite, Direct, Capture

“…37 Resulting from interaction between systems with a discrete spectrum and continuous spectra, Fano resonances have been widely studied for other wave excitations 38 but have been explored and exploited much less in magnonics. 39,40 Here, we will demonstrate retrospectively their relevance to some of our previous observations.…”

One-Dimensional Phononic Crystals

“…In this case a symmetric Fano resonance can be obtained whose width can be tuned by adjusting the frequencies of the zeros of transmission. Such resonances have been found also for acoustic and magnetic circuits formed by a guide inserted between two dangling resonators [130,131].…”

Spectrum and reflection of spin waves in magnonic crystals with different interface profiles

“…15 Hence, we model the magnonic crystal as an infinitely long wire consisting of periodically alternated adjacent uniform layers of two types. The latter layer types differ only by the strength of the uniaxial anisotropy while the easy axis is parallel to the axis of the wire with the associated unit vector denoted as n. This assumption is a reasonable approximation, backed up by the recent progress in fabrication of multilayered magnetic nanowires.…”

“…The study of spin waves and magnonic crystals ͑so-called "magnonics"͒ has been intensively growing recently as a new research field at the interface between nanomagnetism and electromagnetic metamaterials. So, many exciting results have recently been obtained in magnonics by experimental, [4][5][6][7][8][9] theoretical, [10][11][12][13][14][15][16][17] and computational [18][19][20] means.…”