Synthesis and characterization of the heavy-fermion compound CePtAl4Ge2

We report the synthesis of the Ce-based quaternary compound CePtAl4Ge2 that crystallizes in the trigonal structure (space group R3¯m, 166) with unit cell parameters, a = 4.1995(5) Å, c = 31.851(7) Å, and γ = 120°. Powder X-ray diffraction and energy dispersive X-ray spectroscopy show that CePtAl4Ge2 (LaPtAl4Ge2) is in a single, homogeneous phase. Magnetic susceptibility, electrical resistivity, and heat capacity measurements of CePtAl4Ge2 show that it exhibits antiferromagnetic behavior below 2.3 K. The magnetic susceptibility for the magnetic field applied perpendicular (χab) and parallel (χc) to the crystalline c-axis is very anisotropic, and the susceptibility ratio (χab/χc) reaches a maximum value of 10, indicating that the spin easy axis is within the Ce plane. The entropy recovered at TN is consistent with the doublet ground state of the crystal field split J = 5/2 multiplet of Ce3+ ions.