Deciphering the mysteries around Ge ordering in ferromagnetic PrGe_2-x

Studies on binary rare-earth germanides intermetallics show them to be structurally complex with common superstructures α-ThSi₂, α-GdSi₂, and AlB₂ type structures. In most RGe_2–x (R=rare earth) compounds, partial or full ordering of the vacancies is observed, giving rise to a multitude of superstructures resulting in ambiguity in structures, especially if addressed by routine x-ray diffraction methods, and properties. RGe_2–x compounds also show a variety of ground states such as ferro-, antiferro- magnetism and even spin-glass-like behavior. Among these, PrGe_2-x has shown the highest and only ferromagnetic transition temperature (17 – 19 K). Here, we present our findings on the crystal structure and different properties of PrGe_2-x single crystals grown using Ge-self flux. We will compare our findings with those published in the literature.