Exploration of iron-chalcogenide superconductors

TL;DR

This review discusses the development, properties, and unresolved questions of iron-chalcogenide superconductors, emphasizing their unique magnetic features, crystal structures, and phase behaviors since their rise to prominence after 2008.

Contribution

It provides a comprehensive overview of the progress and key issues in understanding iron-chalcogenide superconductors, highlighting recent research findings and ongoing debates.

Findings

Distinct antiferromagnetic ground states in parent compounds

Ease of growing large single crystals

Presence of phase separation phenomena

Abstract

Iron-chalcogenide compounds with FeSe(Te, S) layers did not attract much attention until the discovery of high-Tc superconductivity (SC) in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.