Cs₃V₉Te₁₃: A New Vanadium-Based Material with a Reuleaux-Triangle-Like Lattice and a Possible Phase Transition near 48 K

Exploring and synthesizing materials with new crystal structures provides an important route to discovering exotic quantum phenomena. However, materials with unconventional lattice geometries remain largely unexplored. Here, we report the discovery of a new vanadium-based material, Cs₃V₉Te₁₃, featuring a Reuleaux-triangle-like lattice composed of interwoven triangular, square, and pentagonal motifs. Electrical transport, Hall, and magnetic measurements consistently reveal an anomaly near 48 K, and this feature shows little sensitivity to the applied magnetic field. Specific-heat measurements further confirm the phase transition at 48 K, while the relatively large Sommerfeld coefficient (γ = 195.6 mJ mol^-1 K^-2) suggests strong electronic correlations in Cs₃V₉Te₁₃. In addition, temperature-dependent x-ray diffraction results indicate no obvious structural change across 48 K. Taken together, these results suggest that the anomaly is not induced by a structural transition, but may be associated with an electronic and/or magnetic phase transition. High-pressure transport measurements reveal a highly tunable electronic state in Cs₃V₉Te₁₃, while first-principles calculations suggest electronic features reminiscent of kagome systems and an antiferromagnetic tendency that is progressively suppressed under pressure. These results demonstrate this material, with its structurally novel Reuleaux-triangle-like lattice, as a new platform for exploring the interplay between nontrivial lattice geometry and emergent physical phenomena.