BiS<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>-based layered superconductor Bi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>4</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>4</mml:mn></mml:msub></mml:math>S<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>3</mml:mn></mml:msub></mml:math>

Abstract

Exotic superconductivity has often been discovered in materials with a layered (two-dimensional) crystal structure. The low dimensionality can affect the electronic structure and can realize high transition temperatures (${T}_{\mathrm{c}}$) and/or unconventional superconductivity mechanisms. We show superconductivity in a new bismuth-oxysulfide compound Bi${}_{4}$O${}_{4}$S${}_{3}$. Crystal structure analysis indicates that this superconductor has a layered structure composed of a stacking of spacer layers and BiS${}_{2}$ layers. Band calculation suggests that the Fermi level for Bi${}_{4}$O${}_{4}$S${}_{3}$ is just on the peak position of the partial density of states of the Bi 6$p$ orbital within the BiS${}_{2}$ layer. The BiS${}_{2}$ layer will be a basic structure which provides another universality class for a layered superconducting family, and this opens up a new field in the physics and chemistry of low-dimensional superconductors.