Coexistence of bulk superconductivity and magnetism in CeO₁?_xF_xBiS₂

We show the observation of the coexistence of bulk superconductivity and magnetic ordering in CeO_1-xF_xBiS₂(x = 0 -1.0) prepared by annealing under high pressure. In the CeO_1-xF_xBiS₂ system, both superconductivity and two types of ferromagnetic-like ordering with magnetic transition temperatures of 4.5 and 7.5K are induced upon systematic F substitution. This fact suggests that carriers generated by the substitution of O by F are supplied to not only the BiS₂ superconducting layers but also the CeO blocking layers. Furthermore, the highest superconducting transition temperature is observed when the ferromagnetic-like transition temperature increases, which implies that superconductivity and this magnetic ordering are linked to each other in the CeO_1-xF_xBiS₂ system.