Evolution of magnetic properties along the LnCo₂Al₈ (Ln = La-Nd, Sm and Gd) intermetallic series of compounds

The evolution of the magnetic properties along the series of intermetallic compounds LnCo₂Al₈ (Ln = La-Sm and Gd) is discussed and compared to earlier work [1]. Single crystals of the orthorhombic Pbam structures were grown out of excess Al-flux. Specific heat, anisotropic electrical resistivity, and magnetization measurements indicate that the Ln = Pr, Nd, Sm and Gd compounds order antiferromagnetically, presenting magnetic anisotropy with the easy axis along the crystallographic c-direction. Ln = Pr orders at T_N = 4.9 K with a spin reorientation at 4.6 K while Ln = Nd orders at T_N = 8.2 K with a spin reorientation at 2.7 K. Ln = Sm orders at T_N = 21 K and Ln = Gd orders at T_N = 8.4 K. For Ln = Ce we see signatures of a ferromagnetic-like transition near 5 K. Details of the evolution of metamagnetic transitions as well as possible Kondo-lattice behavior in CeCo₂Al₈ will be discussed.

[1] Cryst. Growth Des. 2015, 15, 7, 3293–3298.