Myriad of correlated electron effects found in the RT₂ Zn₂₀ family

The dilute, rare earth bearing family of RT₂ Zn₂₀ (R = rare earth, T = transition metal) intermetallic compounds can be tuned to a nearly ferromagnetic Fermi liquid that is closer to the Stoner limit than Pd (for R = Y, Lu and T = Fe). The submersion of moment bearing rare earths (Gd-Tm) into this highly polarizable matrix gives rise to exceptionally high temperature ferromagnetism (e.g. T_C = 86 K for GdFe₂ Zn₂₀) for a compound with only one moment bearing ion out of 23 in the formula unit. In addition to this d-shell correlated electron behavior, 4f hybridization gives rise to six, new, Yb-based heavy fermion compounds: YbT₂ Zn₂₀ (T = Fe, Ru, Os, Co, Rh, Ir). These half dozen compounds manifest a range of Yb ion degeneracy values (N) for T ∼ T_K, ranging from N = 4 - 8. Not only do these compounds offer a clear testing ground for the effects of low temperature degeneracy on the correlated electron state, they also present an exceptionally clear experimental confirmation of the generalized Kadowaki-Woods formalism.