Structural and magnetic phase diagram of CeFeAsO1-xFx and its relation to high-temperature superconductivity

Recently, high-transition-temperature (high-T-c) superconductivity was discovered in the iron pnictide RFeAsO1-xFx (R, rare-earth metal) family of materials. We use neutron scattering to study the structural and magnetic phase transitions in CeFeAsO1-xFx as the system is tuned from a semimetal to a high-T-c superconductor through fluorine (F) doping, x. In the undoped state, CeFeAsO develops a structural lattice distortion followed by a collinear antiferromagnetic order with decreasing temperature. With increasing fluorine doping, the structural phase transition decreases gradually and vanishes within the superconductivity dome near x D 0 : 10, whereas the antiferromagnetic order is suppressed before the appearance of superconductivity for x > 0.06, resulting in an electronic phase diagram remarkably similar to that of the high-T-c copper oxides. Comparison of the structural evolution of CeFeAsO1-xFx with other Fe-based superconductors suggests that the structural perfection of the Fe-As tetrahedron is important for the high-T-c superconductivity in these Fe pnictides.