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 groupFd3¯mwith 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 Hf M 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 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 .