Fig. 5: Relative permittivity of UTMFs.
From: Ultrathin 2 nm gold as impedance-matched absorber for infrared light
Extracted relative permittivity for increasing gold layer thickness, based on the fitted Drude model Eq. (1). The solid black line represents the ratio of the imaginary vs real part of the permittivity. For thinner layers, where impedance-matched absorption occurs, the imaginary part strongly dominates with increasing wavelength, in good agreement with the derived criteria Eq. (2). The bulk data is for evaporated gold taken from the ref. 61. Source code available on request.
