Structural Trends and Itinerant Magnetism of the New Cage-structured Compound HfMn${}_2$Zn${}_{20}$

A new cage-structured compound - HfMn${}_2$Zn${}_{20}$ - belonging to the AB${}_2$C${}_{20}$ (A, B = transition or rare earth metals, and C = Al, Zn, or Cd) family of structures has been synthesized via the self-flux method. The new compound crystallizes in the space group Fd-3m with lattice parameter a = 14.0543(2) Å (Z = 8) and exhibits non-stoichiometry due to Mn/Zn mixing on the Mn-site and an underoccupied Hf-site. The structure refines to Hf${}_{0.93}$Mn${}_{1.63}$Zn${}_{20.37}$ and follows lattice size trends when compared to other HfM${}_2$Zn${}_{20}$ (M = Fe, Co, and Ni) structures. The magnetic measurements show that this compound displays a modified Curie-Weiss behavior with a transition temperature around 22 K. The magnetization shows no saturation, a small magnetic moment, and near negligible hysteresis, all signs of the itinerant magnetism. The Rhodes-Wohlfarth ratio and the spin fluctuation parameters ratio both confirm the itinerant nature of the magnetism in HfMn${}_2$Zn${}_{20}$.