Influence of local environment on electronic properties of Co atoms in the Tm3Co11B4 compound

The electronic structure of the Tm₃Co₁₁B₄ compound has been studied by X-ray photoemission spectroscopy and ab initio self-consistent tight binding linear muffin tin orbital (TB LMTO) method. This compound crystallizes in the hexagonal Ce₃Co₁₁B₄-type structure (P6/mmm). We have found a good agreement between the experimental XPS valence band spectra and theoretical ab initio calculations. The calculated total magnetic moment is equal to 13.635 μ_B/f.u. The magnetic moments on the Co atoms are antiparallel to the moments of the Tm atoms. Their values are depended on the local environment, especially on the number of the Co neighbors. The theoretical results are compared with other calculations, saturation magnetization measurements as well as neutron diffraction data for R₃Co₁₁B₄ (R=Y, Nd, Gd, Tb).