**Emerging Superconductivity and Topological States in Bismuth Chalcogenides Bismuth Chalcogenides**

**Emerging Superconductivity and Topological States in** 

DOI: 10.5772/intechopen.73057

Jifeng Shao and Wenka Zhu Jifeng Shao and Wenka Zhu Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73057

#### **Abstract**

In this chapter, we review the recent experimental work in emerging superconductors, i.e., bismuth chalcogenides, including the newly discovered BiS(e)2 -based layered superconductors and some topological superconductor candidates. Their crystal structure and various physical properties are reviewed in detail, with the correlation between structure and superconductivity as the main clue throughout this chapter. Bi2 OS2 is the simplest structure in Bi─O─S compounds and probably the parent compound of this series. Superconductivity emerges when carriers are introduced by intercalation or chemical substitution. The superconducting layer is extended to BiSe2 layer in LaO1−xFx BiSe2 , which has an improved superconductivity. Moreover, the topological insulator Bi2 Se3 can be turned into superconductors by intercalating metal atoms into van der Waals space, e.g., Srx Bi2 Se3 , a potential topological superconductor, whose quantum oscillations reveal a possible topological surface state. The intermediate external pressure can efficiently suppress superconductivity, which reemerges when pressure is further increased, while Tc is nearly invariant in high-pressure region, indicating an unconventional pairing state.

**Keywords:** bismuth chalcogenides, BiS(e)2 -based superconductors, crystal structure, intercalation, topological superconductors, high pressure
