Magnetic behavior of the rare-earth compounds RNiBC by neutron scattering -: art. no. 104410

Neutron diffraction and small angle neutron scattering measurements have been carried out on RNiBC (R=Er, Th, Dy) to investigate the crystallography, magnetic correlations, and long range magnetic ordering. Crystallographic refinements show a strong boron-carbon and nickel-carbon bonding similar to RNiZB2C, but the rare-earth-carbon plane exhibits a buckling which does not exist in the RNi2B2C series. The magnetism in the RNiBC series is quite simple, with a magnetic moment direction going from the a-b plane to the c axis as the atomic number of the rare-earth increases. Er becomes ferromagnetic at T-C= 4.6 K, with a saturated moment of 7.2 mu (B) along the c axis. Th orders ferromagnetically at T-C= 15 K. Below 12.5 K an incommensurate modulation develops with a modulation wave vector of (0 0 1/8), as well as an antiferromagnetic component with k= (0 0 1/2). The moments, which vary in both magnitude and direction, are in the a-b plane with an average value of 7.79 mu (B). DyNiBC exhibits the same behavior, with a T-C and T-N of 17.5 and 13.5 K, respectively.