The evolution of the antiferromagnetic order parameter in CeFeAsO_{1-x}F_{x} as a function of the fluorine content x was investigated primarily via zero-field muon-spin spectroscopy. The long-range magnetic order observed in the undoped compound gradually turns into a short-range order at x=0.04, seemingly accompanied/induced by a drastic reduction of the magnetic moment of the iron ions. Superconductivity appears upon a further increase in doping (x>0.04) when, unlike in the cuprates, the Fe magnetic moments become even weaker. The resulting phase diagram evidences the presence of a crossover region, where the superconducting and the magnetic order parameters coexist on a nanoscopic range.
@article{arxiv.1109.3170,
title = {Long- to short-range magnetic order in fluorine-doped CeFeAsO},
author = {T. Shiroka and G. Lamura and S. Sanna and G. Prando and R. De Renzi and M. Tropeano and M. R. Cimberle and A. Martinelli and C. Bernini and A. Palenzona and R. Fittipaldi and A. Vecchione and P. Carretta and A. S. Siri and C. Ferdeghini and M. Putti},
journal= {arXiv preprint arXiv:1109.3170},
year = {2013}
}