First principles calculations, neutron, and x-ray diffraction investigation of Y3Ni13B2, Y3Co13B2, and Y3Ni10Co3B2

Fully relativistic calculations within the local spin density approximation and the generalized gradient approximation were performed to determine the local spin and orbital magnetic moments, as well as the magnetocrystalline anisotropy energy of Y3Ni13B2, Y3Co13B2, and Y3Ni10Co3B2 compounds. A weak in-plane magnetic anisotropy is determined for Y3Ni13B2, under the assumption of a crystallographic-like magnetic unit cell and collinear magnetic moments. The calculations predict considerable c-axis anisotropy for Y3Co13B2 and Y3Ni10Co3B2, but smaller than that of YCo5. The values of the magnetocrystalline anisotropy energy correlate well with both the magnitude of the orbital magnetic moment and the orbital magnetic moment anisotropy. The mixing between Co or Ni 3d states and B 2p states, observable at the bottom of the valence band of the 3d metal having a boron atom nearest neighbor, decreases the 3d spin and especially, the 3d orbital magnetic moments. Y3Ni13B2 and Y3Ni10Co3B2 were also investigated by powder neutron diffraction experiments, at temperatures between 1.8 and 249 K. The Co and Ni site averaged magnetic moments calculated in the mixed compound are in fair agreement with the values obtained by the refinement of the magnetic contribution to the diffraction pattern