Anisotropic magnetic behavior of single crystalline CeTiGe3 and CeVGe3

We have grown the single crystals of iso-structural CeTiGe₃ and CeVGe₃ compounds by using Ce-Ge eutectic as flux. Using the techniques of magnetization, electrical resistivity and heat capacity, our data on single crystals reveal pronounced magnetic anisotropies in these compounds with hexagonal symmetry. The c-axis is the easy axis of magnetization in CeTiGe₃ which orders ferromagnetically at 14 K, and a gap in the magnon excitation spectra of ∼28 K is inferred from both electrical resistivity and heat capacity. The electrical resistivity of CeTiGe₃ shows anisotropic Kondo behavior and the heat capacity indicates the existence of the first excited crystal electric field split doublet lying at about ∼50 K. The nature of magnetic ordering changes to antiferromagnetic in CeVGe₃, which undergoes a magnetic transition at T_N ∼ 6 K with the a - b plane as the easy plane of magnetization. Below T_N, the electrical resistivity of CeVGe₃ along the c axis shows an upturn due to the opening of a gap. The 4f contribution to the resistivity ρ_4f establishes that CeVGe₃, like the Ti analog, is also a Kondo lattice compound. The present work on single crystals further advances our understanding of these materials based on polycrystalline samples which have been studied earlier in the literature.