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arXiv · 2503.06289

Exploring the interplay between fractionality and PT symmetry in magnetic metamaterials

Mario I. Molina
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Abstract

We study a nonlinear magnetic metamaterial modeled as a split-ring resonator array, where the standard discrete laplacian is replaced by its fractional form. We find a closed-form expression for the dispersion relation as a function of the fractional exponent s and the gain/loss parameter γ and examine the conditions under which stable magneto-inductive waves exist. The density of states is computed in closed form and suggests that the main effect of fractionality is the flattening of the bands, while gain/loss increase tends to reduce the bandgaps. The spatial extent of the modes for a finite array is computed by means of the participation ratio R, which is also obtained in closed form. For a fixed fractionality exponent, an increase in gain/loss γ decreases the overall R, from the number of sites N towards N/2 at large γ. The nonlinear dynamics of the average magnetic energy on an initial ring during a cycle shows a monotonic increase with γ, and it is qualitatively similar for all fractional exponents. This is explained as mainly due to the interplay of nonlinearity and PT symmetry.

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Mario I. Molina. 2025-03-08. Exploring the interplay between fractionality and PT symmetry in magnetic metamaterials. https://arxiv.org/abs/2503.06289

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