Superconductivity in semimetallic Bi3O2S3

Here we report a further investigation on the thermodynamic and transport properties, and an assessment of theoretical calculations, for the BiS2- layered Bi3O2S3 superconductor. The polycrystalline sample is synthesized with a superconducting transition temperature of T onset c = 5.75 K and T zero c = 4.03 K ( T mag c) that drops to 3.3 K by applying a hydrostatic pressure of 6 kbar. Density- of- states ( DOS) calculations give substantial hybridization between Bi, O, and S, with Bi the largest component of DOS, which supports the idea that the BiS2 layer is relevant for producing electron- phonon coupling. An analysis of previously published specific heat data for Bi3O2S3 is additionally suggestive of a strong electron- phonon interaction in the Bi- O- S system. The analysis of the Seebeck coefficient results strongly suggests that Bi3O2S3 is a semimetal. In fact, the semimetallic or narrow band gap behavior may occur in certain other materials in the BiS2- layered class of materials, such as Bi4O4S3.