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) \r{A} (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$_{20}$.