Multiple Distinct Magnetic and Superconducting Phases in LaFeAs_1-xP_xO 1111 Characterized Via X-ray and Neutron Diffraction

Following the discovery of the microscopic co-existence of antifermagnetic spin density waves and superconductivity in Ba_1-xK_xFe₂As₂ and the low temperature structural re-entrance to the novel magnetic C₄ tetragonal phase in Ba_1-xNa_xFe₂As₂, an effort was made to seek similar phases in the related LaFeAs_1-xP_xO 1111 system. Previous work had reported two superconducting domes as well as two distinct magnetic regions. While the low doping magnetic phase had been well characterized by neutron diffraction, the higher doped magnetic region had been deduced from short range ³¹P-NMR measurements. We present a detailed characterization of the nuclear and magnetic structures based on high resolution and high intensity x-ray and neutron powder and single crystal diffraction. Our work demonstrates distinct magnetic symmetries for the two magnetic regions of the phase diagram.