Quantum-critical scaling in the Mn-based kagome metal Sc₃Mn₃Al₇Si₅

Kagome lattices can host a variety of exotic ground states, including quantum spin liquids and correlated phases associated with dispersionless flat energy bands. The Mn-based kagome metal Sc₃Mn₃Al₇Si₅ crystalizes a hexagonal structure in which Mn ions form a kagome network, and shows unusual behavior in transport and thermodynamic properties [1]. Interestingly, a recent study, supported by theoretical calculations, has suggested the presence of orbital-selective flat-band-induced ferromagnetic fluctuations [2]. To elucidate the flat-band-induced ferromagnetic instability, we synthesized single crystals of Sc₃Mn₃Al₇Si₅ and measured charge transport and heat capacity at very low temperatures. We observe no anomaly associated with long-range order in resistivity down to 15 mK and a logarithmic divergence in low-temperature heat capacity. The logarithmic divergence in heat capacity is strongly suppressed by magnetic fields, suggesting a crossover from non-Fermi-liquid to Fermi-liquid behavior, often observed in quantum critical metals. This anomalous crossover in heat capacity is well described by quantum-critical scaling. We will discuss the relationship between the quantum criticality and orbital-selective flat bands in the kagome metal Sc₃Mn₃Al₇Si₅.