Metal-insulator transition in amorphous Ga-Ar mixtures: Critical exponents of electrical transport parameters and behavior of superconductivity

The experimentally determined critical exponents {ν} and g of electrical dc conductivity {σ} and Hall coefficient RH approaching the metal-insulator transition (MIT) from the metallic side in amorphous Gaₓ{Ar}_{1{{-}}x}$ mixtures are {ν}=0.5±{}0.1 and g=0.03±{}0.05, respectively. These exponents are the same as those found in Si:P and Si:As. We thus conclude that the MIT in these systems belong to the same universality class. Furthermore, we find that the disappearance of superconductivity in these mixtures coincides with the MIT.