Material Development and Physical Properties of BiS2-Based Layered Compounds

TL;DR

This review summarizes recent advances in the development, physical properties, and design strategies of BiS2-based layered compounds, highlighting their superconductivity, structural factors, and thermoelectric potential over the past six years.

Contribution

It provides a comprehensive overview of material synthesis, physical properties, and key parameters influencing superconductivity in BiS2-based compounds, including recent design approaches.

Findings

Carrier doping induces bulk superconductivity.

Pressure causes structural transitions enhancing superconductivity.

In-plane chemical pressure suppresses disorder, promoting superconductivity.

Abstract

In 2012, we discovered superconductivity in Bi4O4S3 and LaO1-xFxBiS2, whose crystal structures are composed of alternate stacks of a BiS2-type conduction layer and a blocking layer. Since the discovery, many related superconductors and functional materials have been synthesized. Furthermore, the possibility of unconventional superconductivity has been proposed in recent theoretical and experimental studies. In addition, notable correlations between local structure and physical properties have been revealed in the BiS2-based systems. In this review article, we summarize the material development (probably all the compounds) and physical properties of BiS2-related materials developed in the last six years. The key parameters for the emergence of bulk superconductivity in the BiS2-based compounds are carrier doping to the parent phase (band insulator), pressure-induced structural transition, in-plane chemical pressure, and the suppression of in-plane disorder. We systematically review those parameters and the method of designing new superconductors with BiS2 layers. In addition, studies of BiS2-based compounds as thermoelectric materials are briefly reviewed.