Search for superconductivity near metal-insulator transition in FeB

Recently, possible superconducting phase was reported in the thin film compositional spreads of FeB. In our study, thin films of two different FeB composition spreads were grown by co-sputtering to determine the conditions for appearance of superconductivity in these compounds. Previously, we have shown that metamaterial engineering can enhance superconductivity by creating materials with small dielectric constant (epsilon near zero, or ENZ). In a FeB compositional spread, such conditions should occur in the vicinity of metal-insulator transition (MIT) that should take place when concentration of boron increases in the film. The results of our study of the transport, magnetic, and optical properties for these FeB compositional spreads will be shown. Correlation of MIT and ENZ behavior and their role in possibility of appearance of superconductivity will be discussed.