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

摘要

In this review, we present a summary of the results on single crystal growthof 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 superconductingand magnetic properties (the latter gained mainly from neutron scatteringmeasurements) of these materials are reviewed to demonstrate the connectionbetween magnetism and superconductivity. It will be shown that for the 11system, 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 ismade evident by the strong correlation between the spectral weight around (0.5,0.5) and the superconducting volume fraction. The observation of a spinresonance below the superconducting temperature, Tc, and the magnetic-fielddependence of the resonance, emphasize the important role spin excitations playin the superconductivity. Generally, these results illustrate the similaritiesbetween 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 thatin other iron-based superconductors.