Self-organized vacancy order in Pr 9 Ge 16

In this work, we report the discovery of a new crystal structure on the Ge-rich side of the Pr-Ge binary phase diagram. Using a high-temperature flux technique, we grew single crystals of Pr₉Ge₁₆, which adopt a previously unreported orthorhombic $Fdd2$ structure type featuring ordered Ge vacancies. We present the anisotropic magnetic properties and identify the crystallographic b axis perpendicular to the crystal plane as the magnetic easy axis. Temperature-dependent resistivity measurements reveal metallic behavior with a distinct anomaly at TC = 14.3 K. Hall resistivity data indicate that electronlike carriers dominate, with a carrier concentration on the order of 10²⁷0.16em0exm^-3. The magnetic order is readily suppressed by a magnetic field of approximately 0.4 T applied along the easy b axis.