Superconductivity in Semimetallic Bi3O2S3

TL;DR

This study investigates the superconducting and electronic properties of Bi3O2S3, revealing its semimetallic nature and the influence of pressure on its transition temperature, supported by theoretical calculations and experimental data.

Contribution

It provides the first combined experimental and theoretical analysis of Bi3O2S3, highlighting its semimetallic behavior and the role of BiS2 layers in electron-phonon coupling.

Findings

Superconducting transition temperature is 5.75 K, decreasing to 3.3 K under 6 kbar pressure.

Density-of-states calculations show significant Bi, O, S hybridization.

Seebeck coefficient analysis indicates semimetallic behavior.

Abstract

Here we report further investigation on the thermodynamic, and transport properties, and the first assessment of theoretical calculations for the BiS2-layered Bi3O2S3 superconductor. The polycrystalline sample is synthesized with the superconducting transition temperature of Tc_onset = 5.75 K, that drops to 3.3 K by applying hydrostatic pressure of 6 kbar. Density-of-states calculations give substantial hybridization between Bi, O and S, with the largest Bi component at DOS, which supports the idea that BiS2 layer is relevant for producing electron-phonon coupling. The electron charge carrier concentration of only 1.5 x 10^19 cm-3 for Bi3O2S3 is additionally suggestive of strong electron-phonon interaction in Bi-O-S system. The analysis of Seebeck coefficient results strongly suggests that Bi3O2S3 is a semimetal. In fact, the semimetallic or narrow band gap behavior may be general in the BiS2-layered class of materials, including that of Bi4O4S3.