Discovery of remarkably high magnetic ordering temperatures in dilute rare earth intermetallic compounds

Dilute, rare earth intermetallic compounds are ordered structures in which the rare earth comprises less than $5\%$ atomic of the compound, but still fully occupies a unique crystallographic site. When none of the other elements are moment bearing, it is generally anticipated that such a compound will have magnetic ordering temperatures near 10 K for the R = Gd member of the series and systematically lower temperatures for heavier R members. In this talk we will present a series of dilute rare earth intermetallic compounds that have ferromagnetic ordering temperatures that range from $T_C \sim 90$ K for R = Gd to $T_C \sim 5$ K for R = Tm. The origin of this high ordering temperature as well as systematic trends across the series will be discussed.