Magnetic behaviour of RRh3B3 ternary borides

Magnetisation studies on RRh3B2 (R = La to Gd) ternary borides have shown that all except La containing compound order magnetically. While the magnetic behaviour of PrRh3B2, NdRh3B2 and GdRh3B2 is mainly determined by the localised rare earth moments interacting via the indirect RKKY exchange, the experimental data suggest that the magnetic ordering in CeRh3B2 and EuRh3B2 is of itinerant nature and is presumed to arise from Rh-d band. Possibly the 4f electrons of Ce and Eu also play a significant role. Preliminary resistivity studies on CeRh3B2 show that the temperature behaviour of resistivity is similar to what one would expect for a ''strongly interacting electron gas'', thus making the assumption of itinerant magnetic behaviour in this compound more plausible. 151Eu Moessbauer studies in EuRh3B2 show clearly that Eu ions are non magnetic in this compound and, therefore, magnetic ordering in this compound cannot be ascribed to Eu sublattice. Magnetisation behaviour in SmRh3B2 is rather anomalous. Further experimental work, such as neutron diffraction, is needed to fully understand the exotic magnetic behaviour observed in CeRh3B2 and EuRh3B2 and to some extent in SmRh3B2. (author)