New Kagome Metal Sc₃Mn₃Al₇Si₅ and Its Gallium-Doped Analogues: Synthesis, Crystal Structure, and Physical Properties

Abstract

We report the synthesis, crystal structure, and basic properties of the new intermetallic compound Sc₃Mn₃Al₇Si₅. The structure of the compound was established by single-crystal X-ray diffraction, and it crystallizes with a hexagonal structure (Sc₃Ni₁₁Si₄ type) with Mn atoms forming the Kagome nets. The dc magnetic susceptibility measurements reveal a Curie–Weiss moment of ∼0.51 μ_B/Mn; however, no magnetic order is found for temperatures as low as 1.8 K. Electrical resistivity and heat capacity measurements show that this compound is definitively metallic, with a relatively large specific heat Sommerfeld coefficient, indicating strong electronic correlations. Intriguingly, these features have revealed Sc₃Mn₃Al₇Si₅ as a possible quantum spin liquid. With chemical and lattice disorder introduced by doping, a spin liquid to spin glass transition is observed in the highest Ga-doped compounds. The roles of the geometrically frustrated structure and Mn-ligand hybridization in the magnetism of the title compounds are also discussed