Unusually large coercive field in Sm-Ru-B-C system

In our studies of the quaternary system Sm-Ru-B-C, samples of nominal composition Sm(1)Ru(2)B(2)C(1) and Sm(1)Ru(3)B(3)C(1) gave materials of essentially single phase with a hexagonal structure (a=5.551 A, c=2.976 A and a=5.569 A, c=2.955 A, respectively). The X-ray diffraction patterns resemble that of hexagonal SmRu3B2 (a=5.536 A and c=2.997 A). We suggest that in SmRu3B2 carbon may be partially substituting B or occupy interstitial sites giving materials of the type SmRu3BxCy. The two materials order ferromagnetically with TC∼60 K and ∼50 K, respectively. At 5 K, they show magnetic hysteresis with a very large coercive field, HC ∼15 T. This is perhaps the largest HC at 5 K for a Sm-based material