The simplest iron-based superconductor is the chalcogenide Fe1+yTe1−xSex. Previous work suggested a different magnetic origin of superconductivity owing to differences in its electronic states of this material and the iron pnictides, or at least in their parent compounds —the undoped and non-superconducting versions. The differences are now reconciled by showing a modification of the Fe1+yTe1−xSex states when the Se content is increased.
