Coincidence of the metal-insulator transition and epsilon near zero condition in amorphous FeCuB films

A study of the magnetic, electronic transport, and dielectric properties of a series of sputter grown amorphous FeCuB samples with varying metal/boron content was performed to explore the relationship between the room temperature values of the dielectric function ε(ω) and distance to the disorder-driven metal-insulator transition (MIT). This relationship is relevant to observations that the superconductive transition temperatures (T_c) of many systems is enhanced near the MIT as well as other studies showing that T_c can be enhanced using metamaterial engineering where ε(ω) is negative and near zero (ENZ). The results of the transport, magnetic, and optical properties of these FeCuB films will be presented, and the correlation between MIT and ENZ behavior and their possible influence on the appearance of superconductivity will be discussed.