Superconductor–insulator transition in impurity band systems

Abstract

Motivated by the possible impurity band superconductivity (superfluidity) in B-doped diamond and ultracold atomic gases, we investigate the superconductor–insulator transition (SIT) in disordered systems from the microscopic point of view. We analyze the three-dimensional attractive Hubbard model with point disorders and point out the anomalous metallic state around the SIT induced by the mesoscopic and thermal superconducting (SC) fluctuations. The phase diagram including the host band superconductivity, impurity band superconductivity, Anderson insulator and anomalous metallic state is described. The superconductivity in B-doped diamond is discussed by the comparison with experimental results.