We report our study of the evolution of superconductivity and the phase diagram of the ternary $\text{Fe}{\left({\text{Se}}_{1-x}{\text{Te}}_x\right)}_{0.82}$ $\left(0\le x\le 1.0\right)$ system. We discovered a superconducting phase with $T_{c,\text{max}}=14\text{K}$ in the $0.3<x<1.0$ range. This superconducting phase is suppressed when the sample composition approaches the end member ${\text{FeTe}}_{0.82}$, which exhibits an incommensurate antiferromagnetic order. We discuss the relationship between the superconductivity and magnetism of this material system in terms of recent results from neutron-scattering measurements. Our results and analyses suggest that superconductivity in this class of Fe-based compounds is associated with magnetic fluctuations and therefore may be unconventional in nature.

• Received 15 October 2008

DOI:https://doi.org/10.1103/PhysRevB.78.224503