Strong diamagnetic response in split-ring-resonator metamaterials: Numerical study and two-loop model

We demonstrate that there is a strong diamagnetic response of metamaterials, consisting of open or closed split-ring resonators (SRRs). Detailed numerical work shows that for densely packed SRRs, the magnetic permeability μ(ω) does not approach unity, as expected for frequencies lower and higher than the resonance frequency ω₀. Below ω₀, μ(ω) gives values ranging from 0.9 to 0.6 depending of the width of the metallic ring, while above ω₀, μ(ω) is close to 0.5. Closed rings have μ≈0.5 over a wide frequency range independently of the width of the ring. A simple model that uses the inner and outer current loops of the SRRs can easily explain theoretically this strong diamagnetic response, which can be used in magnetic levitation.