Crystal Growth, Structure, and Physical Properties of Ln₂MGa₁₂ (Ln = La, Ce; M = Ni, Cu)

Single crystals of Ln₂MGa₁₂ (Ln = La, Ce; M = Ni, Cu) have been synthesized using Ga flux and their structures determined by single-crystal X-ray diffraction. The Ln₂MGa₁₂ (Ln = La, Ce; M = Ni, Cu), which is isostructural to Ce₂PdGa₁₂, crystallizes in the tetragonal P4/nbm (No. 125, origin choice 2) space group, with Z = 2 and lattice parameters a ≈ 6.1 Å and c ≈ 15.3 Å. Ce₂NiGa₁₂ orders antiferromagnetically at 10 K and specific heat measurements suggest it is a moderate heavy-fermion system with γ ≈ 191 mJ mol⁻¹ K⁻². Magnetic susceptibility data show paramagnetic behavior down to 2 K for Ce₂CuGa₁₂, whereas specific heat data suggest a magnetic transition below 1.8 K, with a moderately enhanced γ-value of 69 mJ mol⁻¹ K⁻². Metallic behavior is observed below 300 K for each compound. A large positive and nonsaturating magnetoresistance up to 216% at a field (μ₀H) of 9 T is also observed for La₂NiGa₁₂. We present the crystal structures and physical properties of the Ln₂MGa₁₂ (Ln = La, Ce; M = Ni, Cu) series.