Anomalously high Tm for Yb-ions in a new quaternary borocarbide, YbNiBC

We report here the synthesis and magnetic properties of a new quaternary magnetic borocarbide YbNiBC. The material forms in the LuNiBC-type structure with lattice parameters a=3.503 Å and c=7.556 Å. From magnetic susceptibility and heat capacity measurements we find that YbNiBC orders magnetically at T_m∼4 K. As a reference material, we have also synthesized GdNiBC and find that it orders magnetically at ∼14 K which is consistent with an earlier report. T_m of YbNiBC is anomalously higher than that expected on the basis of de Gennes scaling.