Quantum critical point followed by Kondo-like behavior due to Cu substitution in the itinerant antiferromagnet La 2 ( Cu x Ni 1 − x ) 7

La₂ Ni₇ is an itinerant magnetic system with a small ordered moment of ~ 0.1 μB/Ni and a series of antiferromagnetic (AFM) transitions at T₁ = 61.0 K, T₂ = 56.5 K and T₃ = 42.2 K. $M(H)$, and $ρ(H)$ isotherms as well as constant field $M(T)$ and $ρ(T)$ measurements on single crystalline samples manifest a complex, anisotropic $H-T$ phase diagram with multiple phase lines. Here we present the growth and characterization of single crystals of the La₂(CuₓNi₁₋ₓ)₇ series for 0 ≤ x ≤ 0.181. We measured powder x-ray diffraction, and composition, as well as anisotropic $R(H,T)$, $M(H,T)$, and Cₚ(T) on these single crystals. Using the measured data, we infer a $(T-x)$ phase diagram to study the evolution of the AFM ordering upon Cu substitution. For 0 ≤ x ≤ 0.097, the system remains magnetically ordered at base temperature with x ≤ 0.012, showing signs of multiple AFM ordering temperatures. For the higher substitution levels, 0.125 ≤ x ≤ 0.181, there are no signatures of magnetic ordering, but anomalous features in $R(T)$ and Cₚ(T) data are observed which are consistent with the Kondo effect in this system. The intermediate x = 0.105 sample lies between the magnetic ordered and the Kondo regime and is in the vicinity of the AFM-quantum critical point (QCP). Thus, La₂(CuₓNi₁₋ₓ)₇ is an example of a small moment system that can be tuned through a QCP. Given these data combined with the fact that the La₂ Ni₇ structure has kagome-like, Ni-sublattices running perpendicular to the crystallographic c axis, and a predicted $3d$-electron flat band that contributes to the density of states near the Fermi energy, La₂(CuₓNi₁₋ₓ)₇ becomes a promising system to host and study exotic physics.