Crystal structure and magnetic properties of the breathing kagome Ising antiferromagnet Yb₃Ni₁₁Ge_4.63

We have investigated magnetic properties of the rare-earth based intermetallic compound Yb₃Ni₁₁Ge_4.63 (YNG), where Yb³⁺ ions form a breathing-kagome lattice. Single-site 4f electron wavefunctions of the ground-state doublet are deduced from magnetization and heat capacity measurements. The Weiss temperatures are quite anisotropic as Θ^a = −0.01(2) K (H ∥ a) and Θ^c = −0.67(2) K (H ∥ c), indicating Ising-like spin–spin interactions dominating in this compound. Low-temperature neutron diffraction confirms absence of magnetic Bragg peaks down to 0.05 K, whereas enhancement of broad peaks below 0.8 K was observed, a signature of short-range spin correlations. Competing interactions on the breathing-kagome lattice would suppress a magnetic long-range order in YNG. (author)