Magnetic properties of Sm–Ru–B–C

Abstract A series of quaternary intermetallics having the nominal composition Sm(1)Ru( n )B( n )C(1), (designated as 1nn1 compounds, n =1, 2, 3 and 4), have been prepared by arc melting route. X-ray diffraction patterns reveal two types of compounds in the case of 1441 nominal composition. One has a bct structure ( a =7.484 A and c =14.997 A) with small amount of some impurity phases; another is a mixture of a bct phase ( a =7.485 A and c =14.982 A) and a hexagonal phase ( a =5.566 A and c =2.944 A) in the proportion 1:2. The observed phases resemble SmRu 4 B 4 (bct, a =7.482 A and c =15.049 A) and SmRu 3 B 2 (hexagonal, a =5.536 A and c =2.997 A). In SmRu 4 B 4 C, superconductivity around 12 K has been reported in the literature whereas no superconductivity is observed down to 4.2 K in any of our samples. Surprisingly, the 1221 and 1331 samples resulted in materials of essentially single phase with a hexagonal structure having lattice constants ( a , c )=(5.551, 2.976) A and (5.569, 2.955) A, respectively, which resembles that of SmRu 3 B 2 , but with distinctly different cell constants. They exhibit ferromagnetic order with T C ∼60 K and ∼50 K, respectively. At 5 K, they exhibit magnetic hysteresis with a very large coercive field H C of about 15 T. All the samples of 1111 nominal composition resulted in multiphasic materials and showed two weak magnetic transitions in the temperature range (50–70) K, and a prominent ferromagnetic transition below 4 K.