Abstract
We have experimentally determined the complex permittivity of a high entropy alloy (HEA) composed of five noble metals: Au, Ag, Cu, Pd, Pt. The permittivity was measured in a wide range of wavelengths from ultraviolet via visible to mid-infrared. The experiments and numerical simulation results show a possibility to create perfect absorber and emitter metasurfaces from such noble HEA. The lattice constant and electron work function of the noble HEA were determined to be 0.396 nm and 4.8 pm 0.4 eV, respectively.