Magnetic and crystallographic structure of ${\mathrm{Y}}_6$${\mathrm{Mn}}_{23}$${\mathrm{D}}_{23}$

The magnetic behavior of ${\mathrm{Y}}_6$ ${\mathrm{Mn}}_{23}$ is dramatically altered upon hydrogenation (or deuteration). In this study it has been found, by means of high-resolution powder diffraction and Rietveld refinement techniques, that the crystallographic structure is distorted from face-centered cubic ($\mathrm{Fm}3m$) at 295 K to a primitive tetragonal structure at 4 K in which deuterium atoms are atomically ordered. ${\mathrm{Y}}_6$ ${\mathrm{Mn}}_{23}$ is a ferromagnetic compound with $T_c=486\mathrm{}$ K, and bulk magnetization of $\frac{13.2{\mu }_B}{\mathrm{f}.\mathrm{u}.\mathrm{}}$ (formula unit). After deuteration of ${\mathrm{Y}}_6$ ${\mathrm{Mn}}_{23}$ to the composition ${\mathrm{Y}}_6$ ${\mathrm{Mn}}_{23}$ ${\mathrm{D}}_{23}$, low-temperature scattering data ($T<\mathrm{}180\mathrm{}$ K) show that the $b$ and $f_2$ sites in the $\mathrm{Fm}3m$ structure are antiferromagnetic and the $d$ and $f_1$ sites have no spontaneous magnetic moment.