Study of the Magnetic Structure in Gd5Ge4

Gd$_{5}$Ge$_{4}$ - Gd$_{5}$Si$_{4}$~based compounds show promising applications due to magneto-caloric, magneto-strictive, and magneto-resistance properties. Gd$_{5}$Ge$_{4}$ crystallizes in the orthorhombic space group \textit{Pnma}, and orders antiferromagnetically below the temperature $T_{N}$~$\sim $~ 127~K. The details of the magnetic structure, however, have not been determined because of the strong neutron absorption of natural Gd. We have employed X-ray Resonant Magnetic Scattering (XRMS) to elucidate the details of the magnetic structure. The magnetic unit cell is the same as the chemical unit cell. Azimuthal scan of the (0 3 0) magnetic peak indicates that the main magnetic moment component lies along the \textbf{\textit{c}} axis. From the azimuthal scan and the $Q$ dependence of the magnetic scattering, all three atomic sites are in the same magnetic space group \textit{Pnm'a}. No clear component of magnetic moment along the \textbf{\textit{a}} direction was seen.