Dynamic and Structural Critical-like Behaviors in glassy monolayers of colloidal ellipsoids

Whether the glass transition is a purely dynamic transition or a thermodynamic one is a long-standing debate in condensed matter physics. Critical behaviors have been found in translational degree of freedom in glasses composed of spheres with local polycrystalline structures, but it is not clear if criticality exists in more general glassy systems without crystalline orders or composed of non-spherical particles. Here, we show rich critical behaviors in both translation and rotation in monolayers of monodispersed colloidal ellipsoids lacking crystal-like structures. We found an Ising criticality at the ideal glass transition point φ₀ for the static glassy structures, local structural entropies and dynamic slow-moving clusters. These structural and dynamic quantities sharing the same Ising criticality are a direct evidence of the critical phenomenon and thermodynamic nature of the glass transition at φ₀. A different criticality is found at the mode-coupling point φ_C for the fast-moving clusters reflecting a dynamic glass transition. These results may explain the theoretical puzzles that the dynamic correlation length diverges at two different temperatures and the relaxation mechanism changes around T_C.