Absence of strong magnetic fluctuations in the iron phosphide superconductors LaFePO and Sr2ScO3FeP

TL;DR

This study used neutron scattering to investigate magnetic fluctuations in LaFePO and Sr2ScO3FeP, finding no evidence of such fluctuations, which implies they may not play a significant role in these iron phosphide superconductors.

Contribution

The paper provides the first neutron scattering measurements on LaFePO and Sr2ScO3FeP, showing the absence of magnetic fluctuations in these materials, contrasting with other iron-based superconductors.

Findings

No magnetic fluctuations detected in LaFePO and Sr2ScO3FeP.

Magnetic signals are at least 4 to 7 times weaker than in related superconductors.

Magnetic fluctuations are likely less influential in iron phosphide superconductors.

Abstract

We report neutron inelastic scattering measurements on polycrystalline LaFePO and Sr2ScO3FeP, two members of the iron phosphide families of superconductors. No evidence is found for any magnetic fluctuations in the spectrum of either material in the energy and wavevector ranges probed. Special attention is paid to the wavevector at which spin-density-wave-like fluctuations are seen in other iron-based superconductors. We estimate that the magnetic signal, if present, is at least a factor of four (Sr2ScO3FeP) or seven (LaFePO) smaller than in the related iron arsenide and chalcogenide superconductors. These results suggest that magnetic fluctuations are not as influential on the electronic properties of the iron phosphide systems as they are in other iron-based superconductors.