Elucidating the magnetic and superconducting phases in Rb$_{x}$Fe$_{y}$Se$_{2-z}$S$_{z}$.

The complex interdigitated phases have greatly frustrated attempts to document the basic features of the superconductivity in the $A_{x}$Fe$_{y}$Se$_{2-z}$S$_{z}$ ($A=$ alkali metals) system. We have employed elastic neutron scattering, energy-dispersive x-ray spectroscopy, and resistivity measurements to elucidate the relations of these phases in Rb$_{x}$Fe$_{y}$Se$_{2-z}$S$_{z}$.We find: i) the iron content is the driving parameter in stabilizing the structural separated phases; ii) the existence of~the~245 antiferromagnetic phase stabilizes the iron vacancy free phase; iii) the sulfur substitutions progressively tune the iron vacancy free phase from a superconductor in Rb$_{x}$Fe$_{2}$Se$_{2}$ to a metallic phase in Rb$_{x}$Fe$_{2}$S$_{2}$. Several phase diagrams as functions of the iron content and the Se:S ratio will be provided.