Revealing hidden atomic ordering in FeMn(P,Ge)

In the magnetic refrigeration system FeMn(P,Si), there is a known ordering of the metals on two crystallographic sites. However, any ordering of the non-metals, on their two sites are currently unknown. P and Si have a very similar scattering power using both X-rays and neutron scattering methods, making them experimentally challenging to separate. By substitution Si with Ge, this challenge can be overcome making it possible to experimentally verify any preferred occupancy in the FeMn(P,Si/Ge)-system. This proposed experiment will study the nuclear structure for FeMnP0.67Ge0.33 at elevated temperature making the nuclear structure possible to analyse. These results will provide a deeper understanding of magnetic cooling materials based on Fe2P, and will also be essential to analyse the existing low temperature neutron diffraction data which also contains magnetic structure information.