Multiple Magnetic Phases Hiding in Plain (and Out-of-Plane) Sight in Coexistence with Superconductivity in LaFeAs<sub>1-x</sub>P<sub>x</sub>O 1111 System
ORAL
Abstract
Following the discrovery of the microscopic co-existence of antifermagnetic spin density waves and superconductivity in Ba1-xKxFe2As2 and the low temperature structural re-entrance to the magnetic C4 tetragonal phase in Ba1-xNaxFe2As2, an effort was made to seek similar phases in the related LaFeAs1-xPxO 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 phase diagram with nuclear and magnetic structural characterization based on a combination of x-ray and neutron diffraction, as well as magnetic temperature dependence thoroughly mapped by muon spin resonance. This work demonstrates three distinct magnetic phases evolving from in-plane orthorhombic to in-plane tetragonal to out-of-plane tetragonal permeating the entire phase diagram from the parent LaFeAsO to superconducting LaFeAs0.2P0.8O.
*Work at the Materials Science Division at Argonne National Laboratory was supported by the US Department of Energy, Office of Science, Materials Sciences and Engineering Division.
