Two-dimensional superconductivity induced by electronic excitations

As a nonphonon mechanism of superconductivity, Little has proposed models in which the pairing force is induced by electronic polarizability of molecules embedded in the conductor. Hirsch and Scalapino have studied a model of this type in one dimension and have found that superconductivity is dominated by charge-density wave. Here, their calculations are extended to two dimensions. Numerical data from quantum Monte Carlo calculations suggest that the charge-density-wave formation is limited to a region close to half filling. Outside of that superconductivity develops unhindered. The theoretical results might be relevant to high-temperature superconductors.