Itinerant-electron ferromagnetism in R Rh6b4 (R=Y,Lu,La,Eu3+)

X-ray, magnetization, and Mössbauer studies of new hexagonal compounds RRh6B4 (R=rare earth) were performed. YRh6B4 and LuRh6B4 exhibit strongly enhanced itinerant paramagnetism. LaRh6B4 and Eu3+Rh6B4 exhibit itinerant-electron ferromagnetism (Tc=6 and 19 K) with large magnetic anisotropy and hysteresis [Hc(EuRh6B4)=2.1 kOe at 4.1 K]. All systems, when doped with 0.5 at.% Fe, show very high Curie points (100 to 300 K) and moments per Fe ion of up to 8μB.