Magnetic properties of CeT_xGa_4−x (T=Cu, Ag) single crystals

We have succeeded in growing single crystals of BaAl₄-type CeTGa₃ (T = Cu, Ag) by Ga self-flux method for the first time. In spite of several starting compositions, the resulting single crystals have partial replacement of T sites (2a sites) with Ga and their compositions are always the same, i.e., CeCu_0.8Ga_3.2 and CeAg_0.7Ga_3.3. For both compounds, a step like increase is observed at the low field in M(H) of a-axis at 1.8 K in addition to the strong enhancement below 5 K in M(T). The magnetic susceptibilities can be well explained by the crystalline electric field model. On the other hand, in p(T), distinct kinks are shown at 4.8 K for CeCu_0.8Ga_3.2 and at 3.9 K for CeAg_0.7Ga_3.3, but no clear −logT term are shown for both compounds. These results indicate that CeCu_0.8Ga_3.2 and CeAg_0.7Ga_3.3 are localized ferromagnets, which have easy axes of magnetization along a-axes, with the Curie temperature being 4.8 K and 3.9 K, respectively.