Investigation of Mn, Fe, and Ni Incorporation in CeCo₂Al₈

Single crystals of CeCo_2–xM_xAl₈ (M = Mn, Fe, Ni; 0 ≤ x < 1) were grown and characterized by X-ray diffraction and magnetic susceptibility. The unit cell volumes of Mn-doped compounds increase and those of Ni-doped compounds decrease with increasing dopant concentration. All samples display a magnetic ordering near 6 K with magnetic moments of the analogues ranging from 2.61 to 2.81 μ_B/mol Ce and slightly higher than Ce³⁺ only magnetic moment. The unit cell volumes of Fe-doped compounds also increase with increasing Fe concentration. However, the cell volume of CeCo_2–xFe_xAl₈ decreases for x = 1.00 and is not Curie–Weiss possibly because of valence fluctuation.