Interplay between magnetism and superconductivity in iron-chalcogenide superconductors: crystal growth and characterizations

TL;DR

This review summarizes the crystal growth methods and magnetic-superconducting interplay in iron-chalcogenide superconductors, highlighting the role of spin excitations and magnetic order in their superconducting properties.

Contribution

It provides a comprehensive overview of growth techniques and magnetic interactions in Fe(1+y)Te(1-x)Se(x) and A(x)Fe(2-y)Se(2) superconductors, emphasizing the connection between magnetism and superconductivity.

Findings

Spin excitations around (0.5, 0.5) are linked to superconductivity.

Magnetic order around (0.5, 0) competes with superconductivity.

Superconductivity in A(x)Fe(2-y)Se(2) borders an antiferromagnetic insulating phase.

Abstract

In this review, we present a summary of the results on single crystal growth of two types of iron-chalcogenide superconductors, Fe(1+y)Te(1-x)Se(x) (11), and A(x)Fe(2-y)Se(2) (A= K, Rb, Cs, Tl, Tl/K, Tl/Rb), using Bridgman, zone-melting, vapor self-transport, and flux techniques. The superconducting and magnetic properties (the latter gained mainly from neutron scattering measurements) of these materials are reviewed to demonstrate the connection between magnetism and superconductivity. It will be shown that for the 11 system, while static magnetic order around the reciprocal lattice position (0.5, 0) competes with superconductivity, spin excitations centered around (0.5, 0.5) are closely coupled to the materials' superconductivity; this is made evident by the strong correlation between the spectral weight around (0.5, 0.5) and the superconducting volume fraction. The observation of a spin resonance below the superconducting temperature, Tc, and the magnetic-field dependence of the resonance, emphasize the important role spin excitations play in the superconductivity. Generally, these results illustrate the similarities between the iron-based and cuprate superconductors. In A(x)Fe(2-y)Se(2), superconductivity with Tc ~ 30 K borders an antiferromagnetic insulating phase; this is closer to the behavior observed in the cuprates but differs from that in other iron-based superconductors.