Geometrical frustration arises when the lattice geometry prevents local interaction energies from minimizing simultaneously. Whether and how geometrically frustrated spins or charges in clean crystals exhibit glassy dynamics remain elusive due to the lack of measurements on microscopic dynamics. Here we employed buckled monolayer colloidal crystals to mimic frustrated antiferromagnetic Ising spins on triangular lattices, and measured single-spin dynamics using video microscopy. Both attractive and repulsive colloidal crystals buckled into zigzag stripes with glassy dynamics at low effective temperatures in experiment and simulation. The simple local spin configurations enable uncovering correlations among structure, dynamics and soft vibrational modes. Machine learning analysi...[ Read more ]

Geometrical frustration arises when the lattice geometry prevents local interaction energies from minimizing simultaneously. Whether and how geometrically frustrated spins or charges in clean crystals exhibit glassy dynamics remain elusive due to the lack of measurements on microscopic dynamics. Here we employed buckled monolayer colloidal crystals to mimic frustrated antiferromagnetic Ising spins on triangular lattices, and measured single-spin dynamics using video microscopy. Both attractive and repulsive colloidal crystals buckled into zigzag stripes with glassy dynamics at low effective temperatures in experiment and simulation. The simple local spin configurations enable uncovering correlations among structure, dynamics and soft vibrational modes. Machine learning analysis further revealed facilitated dynamics to be an important mechanism of structural relaxation. Moreover, our simulation revealed a similar structure and dynamics in lattice Coulomb liquids. Hence, spin-lattice coupling and long-range interaction can similarly lift degeneracy, induce a rugged landscape and thus produce glassy dynamics. With machine learning methods, we can further resolve the relation between facilitation and local structural signatures.