Discovery of a Superconductor Bi5O4S3Cl Containing the Unique BiS3 Layer

The BiS2-based layered superconductors with structures similar to those of cuprates and iron-based superconductors have stimulated much research interest. Here, a new quaternary compound is reported, Bi5O4S3Cl, which crystalizes in a tetragonal structure with P4/mmm (No. 123) space group having alternately stacking unique BiS3 layers and Bi2O2 layers along the c-axis with a Cl atom located at the center of the unit cell. A superconducting transition above 3 K is observed for both electrical transport and magnetic measurements. Hall resistivity measurements show its multiband character with a conduction dominated by electron-like charge carriers. The first-principles calculations exhibit that the semiconducting parent phase Bi5O4S3Cl becomes metallic when sulfur vacancies are introduced, which hints the origin of superconductivity in Bi5O4S3Cl. The findings will inspire the exploration of new BiS-based superconductors.